+++ONLINE KOLLOQUIUM+++ Superconducting opto-electronic circuits and applications (Dr. Sonia Buckley)

  • Online kolloquium on July 21th, 2020 at 4:30 p.m. if online only!
  • Date: Jul 21, 2020
  • Time: 16:30
  • Speaker: Dr. Sonia Buckley
  • National Institute of Standards and Technology (NIST), Gaithersburg Maryland, USA
  • Location: +++ONLINE KOLLOQUIUM+++
While traditional computers can simulate the function of the biological brain, this comes at a huge disadvantage in terms of speed and energy use. However, directly emulating the structure of the brain in hardware is extremely challenging due to the very high physical fanout, localized memory and analog/digital hybrid computation. [more]
Attosecond time-resolved photoelectron spectroscopy provides new insights into the photoelectric effect and gives information about the relative as well as absolute timing of photoemission from different electronic states like core versus valence band states within the electronic band structure of solids. [more]

+++Online Kolloquium+++ Continuous Quantum Light from a Dark Atom (M. Sc. Bo Wang)

Single photons can be generated from a single atom strongly coupled to a optical cavity via a stimulated Raman adiabatic passage between two atomic ground states [1]. During the generation of the photon, the atom stays within the dark state of electromagnetically induced transparency(EIT) avoiding spontaneous decay from the excited state. [more]

+++ONLINE KOLLOQUIUM+++ Surprises from Time Crystals (Prof. Vedika Khemani)

Recent years have witnessed a remarkable confluence of diverse areas of physics coming together to inform fundamental questions about many-body quantum matter. A unifying theme in this enterprise has been the study of many-body quantum dynamics in systems ranging from electrons in solids to cold atomic gases to black holes. [more]

+++ONLINE KOLLOQUIUM+++ A subradiant atomic mirror (M. Sc. David Wei)

When quantum emitters are spatially structured on sub-wavelength scales, photon-mediated dipole-dipole interactions can strongly alter the spectral and directional radiative response. Tightly trapped atoms in optical lattices, only coupled to the electromagnetic vacuum, constitute ideal dipolar emitters to study such cooperative behaviour. [more]
Laser frequency combs enable new approaches to molecular spectroscopy [1]. Dual-comb spectroscopy, a technique of Fourier-transform interferometry with two frequency combs of slightly different repetition rates, holds much promise for broadband, high-¬resolution, precise, and sensitive molecular fingerprinting. Its development in the mid-infrared region (2-20 µm), where most molecules have strong rovibrational transitions, is of fundamental interest to molecular science, though technically challenging. [more]

+++ONLINE TALK+++ Novel avenues for robust free-space quantum communications (Prof. Thomas Jennewein)

Quantum information processing and quantum communication are novel protocols that originate from the very fundamental and philosophical questions on superposition and entanglement raised since the early days of quantum mechanics. Strikingly, these new protocols offer capabilities beyond communication task possible with classical physics. [more]

+++ONLINE KOLLOQUIUM+++ (MCQST-Kolloquium) Topological materials science (Prof. Claudia Felser)

Topology, a mathematical concept, recently became a hot and truly transdisciplinary topic in condensed matter physics, solid state chemistry and materials science. Since there is a direct connection between real space: atoms, valence electrons, bonds and orbitals, and reciprocal space: bands, Fermi surfaces and Berry curvature, a simple classification of topological materials in a single particle picture should be possible. [more]

+++ONLINE KOLLOQUIUM+++ Circular Rydberg atoms : exploring and harnessing the quantum (Prof. Jean-Michel Raimond)

Circular Rydberg atoms are ideal tools for exploring and harnessing the quantum. These very excited states, the closest to the Bohr circular orbit model, feature a very long lifetime, an extremely strong coupling to electromagnetic fields and a large dipole-dipole mutual interaction. [more]

+++ONLINE KOLLOQUIUM+++ Levitodynamics (Prof. Lukas Novotny)

I discuss our experiments with optically levitated nanoparticles in ultrahigh vacuum. Using both active and passive feedback techniques we cool the particle’s center-of-mass temperature below T 100μK and reach mean quantum occupation numbers of n = 4. [more]

+++ONLINE KOLLOQUIUM+++ Solving the Proton Radius Puzzle (Prof. Douglas Higinbotham)

For many years scientists believed that the proton radius was 0.877(6) fm based on a series of atomic Lamb shift and electron scattering measurements. In 2010, a new type of measurement, making use of muonic hydrogen, determined the radius to be 0.842(1) fm. [more]
The role of molecular spectroscopy in physics has evolved over the years. It was traditionally used to study molecular structure and its underlying quantum mechanics. Later, it led to various applications, including the first “atomic clock” that was actually based on molecular vibrations. More recent advances in techniques for quantum manipulation of molecules bring new directions including the use of molecules to search for new physics, harnessing molecular resources for quantum engineering, and exploring chemical reactions in the ultra-low temperature regime. [more]

+++ONLINE KOLLOQUIUM+++Large-Scale Quantum Photonics for Computing and Communications (Prof. Dirk Englund)

Recent advances in materials, control, and nanofabrication now open the prospect for scalable quantum technologies based on solid-state quantum systems. In particular, photonic integrated circuits (PICs) now allow routing photons with high precision and low loss, and solid-state artificial atoms provide high-quality spin-photon interfaces. [more]

+++ONLINE KOLLOQUIUM+++Collectively encoded qubits using Rydberg polaritons (Prof. Charles Adams)

Rydberg atoms offer a versatile platform for a range quantum applications including quantum computing, quantum optics and sensing. Whereas Rydberg quantum computers use individual atoms in an optical tweezer array, quantum non-linear optics is mainly based on ensembles. In this talk, I discuss a hybrid approach where individual qubits are encoded in atomic ensembles. [more]
Far-IR lasers have fallen largely in disuse due to their very limited tunability, poor power efficiency and bulk. We have realized compact, widely frequency-tunable, bright far IR lasers: a gas-phase molecular laser based on rotational population inversion optically pumped by a quantum cascade laser. [more]
Cold atom clouds scattering light appear are an ideal platform tocouple atoms, either classically or quantum-mechanically, thanks tothe long-range interactions mediated by the light: In 3D, thedipole-dipole interaction present a long-range 1/r decay, which givesrise to macroscopic modes and 'cooperative' effects. [more]
Traditional quantum interfaces between atomic ensembles and light have relied upon disordered three-dimensional atomic gases. Recently, however, there have been significant efforts toward exploring whether ordered arrays of atoms can give rise to qualitatively different quantum optical phenomena and functionality, specifically due to strong interference in light emission arising from spatial ordering. Here, we discuss ongoing work to explore this question in two-dimensional arrays. [more]

Parity Measurements in Action: Detecting Errors in the Surface Code and Heralding Itinerant Cat States using Superconducting Circuits (Prof.Christopher Eichler)

Parity Measurements in Action: Detecting Errors in the Surface Code and Heralding Itinerant Cat States using Superconducting Circuit
Parity measurements distinguish between quantum states with an even and an odd number of excitations without revealing any additional information about the state. Nondestructive parity detection allows one to project onto highly entangled states and therefore plays a central role in quantum error correction. [more]

Simulating quantum magnetism with quantum dot Arrays (Prof. Lieven Vandersypen)

Simulating quantum magnetism with quantum dot Arrays
Gate-defined quantum dots have recently emerged as an attractive platform for analog quantum simulation. A quantum dot array naturally emulates the extended Fermi-Hubbard model. The energy scales cover the most relevant parts of the phase diagram, with individually tunable hopping energies well below the on-site interaction energies and at the same time far exceeding the thermal energy. In addition, site-specific potential offsets are individually tunable, further extending the range of physical phenomena that can be explored. [more]

The quantum phases of dipolar quantum gases ( Porf. Francesca Ferlaino)

The quantum phases of dipolar quantum gases
Ultracold quantum gases are a powerful platform to address key questions in quantum physics and a powerful resource to realize novel paradigms and novel phases of quantum matter. Moreover, the potential of such systems is becoming ever more enabling as scientists acquire an increasingly fine control over optical manipulation and inter-particle interactions. [more]

From Optical Communications to the Brain: Integrated Photonics on Silicon (Prof. Joyce Poon)

From Optical Communications to the Brain: Integrated Photonics on Silicon
Foundry-manufactured, monolithically integrated multilayer silicon nitride-on-silicon photonic platforms are suitable for large-scale photonic circuits. [more]

Ultracold atoms carrying orbital angular momentum in lattices of rings: topology and quantum magnetism ( Prof. Veronica Ahufinger)

Ultracold atoms carrying orbital angular momentum in lattices of rings: topology and quantum magnetism
In this talk, we discuss the physics of ultracold atoms carrying Orbital Angular Momentum (OAM) in lattices of ring potentials both in the single-particle and in the Mott insulator limits. In the former limit, we find topologically protected edge states. In the latter limit, we show that the system can realize a variety of spin-1/2 models, including the XYZ Heisenberg model with or without external field. [more]

Polariton-electron interactions in two dimensional materials (Prof. Atac Imamoglu)

Polariton-electron interactions in two dimensional materials
Two dimensional materials provide new avenues for synthesizing compound quantum systems. Monolayers with vastly different electric, magnetic or optical properties can be combined in van der Waals heterostructures which ensure the emergence of new functionalities; arguably, the most spectacular example to date is the observation of strong correlations and low electron density superconductivity in Moire superlattices obtained by stacking two monolayers with a finite twist angle. [more]

Heavy Neutrinos as a Key to understand the Universe (Prof. Marco Drewes)

Heavy Neutrinos as a Key to understand the Universe
Neutrino flavour oscillations indicate that neutrinos have tiny masses. They are the only firmly established proof of physics beyond the Standard Model of particle physics that has been observed in the laboratory. Understanding the origin of neutrino masses may therefore provide a key to understand how the Standard Model should be embedded in a more fundamental theory of Nature. [more]

Topological Superconductivity and Majorana Fermions in Coupled Wires (Fan Yang)

Topological Superconductivity and Majorana Fermions in Coupled Wires
In the first part, we present a theoretical study of the interplay between topological p-wave superconductivity, orbital magnetic fields and quantum Hall phases in coupled wire systems. We consider two-dimensional systems made of weakly coupled ladders. There, we engineer a p+ip superconductor with the chiral Majorana edge current and describe a generalization of the ν = 1/2 fractional quantum Hall phase. These phases might be realized in solid-state or cold-atom nanowires. For the second part, we will address the spin ladder analogs of the Kitaev honeycomb model. A generalized phase diagram for the two-leg ladder system is obtained together with a driven time-dependent protocol based on superconducting box circuits. [more]

Complexity in quantum field theory (Dr. Michal Heller)

Complexity in quantum field theory
Recent developments in holography (AdS/CFT) has led to a conjecture that spacetime volume inside a black hole is related to complexity in a dual quantum field theory. This development has provided strong stimulous for understanding definitions and properties of complexity in quantum field theory and I will review some of the results in this emerging area. [more]

Quantum optics and quantum information science in multi-dimensional photonics Networks (Prof. Christine Silberhorn)

Quantum optics and quantum information science in multi-dimensional photonics Networks
Photonic quantum systems, which comprise multiple optical modes as well as highly non-classical and sophisticated quantum states of light, have been investigated intensively in various theoretical pro­posals over the last decades. The ideas cover a large range of different applications in quantum technology, spanning from quantum communication and quantum metrology to quantum simulations and quantum computing. However, the experimental implementations require advanced setups of high complexity, which poses a considerable challenge. The successful realization of controlled quantum network structures is key for the future advancement of the field. [more]

Ultrafast road to extremely efficient chiral light matter interaction ( Prof. Olga Smirnova)

Ultrafast road to extremely efficient chiral light matter interaction
Chirality plays a key role in physics, chemistry and biology. In the molecular world, the non-superimposable mirror twins of the same chiral molecule – the left-handed and right handed enantiomers – have the same physical properties unless they interact with another chiral object. Distinguishing left- and right-handed molecular enantiomers is very challenging, especially on ultrafast time scale, with standard all-optical techniques leading to extremely weak chiral signals. [more]

A step for gauge fields in lattices and a twist by Dissipation ( Prof. Tilman Esslinger)

A step for gauge fields in lattices and a twist by Dissipation
The coupling between gauge and matter fields plays an important role in many models of high-energy and condensed matter physics. In these models, the gauge fields are dynamical quantum degrees of freedom in the sense that they are influenced by the spatial configuration and motion of the matter field. So far, synthetic magnetic fields for atoms in optical lattices were intrinsically classical, as these did not feature back-action from the atoms. [more]

Quantum Critical Metals

Quantum Critical Metals
Metallic quantum critical phenomena are believed to play a key role in many strongly correlated materials, including high temperature superconductors. Theoretically, the problem of quantum criticality in the presence of a Fermi surface has proven to be highly challenging. However, it has recently been realized that many models used to describe such systems are amenable to numerically exact solution by quantum Monte Carlo (QMC) techniques, without suffering from the fermion sign problem. [more]
The molecular composition of systemic biofluids is a sensitive indicator of human physiological states, very relevant for disease detection and health monitoring. Thus, the capability of observing signatures of miniscule changes in concentration of a wide variety of molecules embedded in complex organic consortia of liquid biopsies is crucial for advancing systems biology and medical diagnostics. [more]

Double Feature: Anomalous Floquet phases in periodically-driven hexagonal lattices (M.Sc. Karen Wintersperger)

Double Feature: Anomalous Floquet phases in periodically-driven hexagonal lattices
Ultracold atoms in periodically-driven optical lattices can be used to simulate systems with nontrivial topological properties. Due to the periodic driving, energy conservation is relaxed which makes it possible to realize systems with properties that go beyond those of conventional static systems. For instance, chiral edge modes can exists even if the bulk is topologically trivial [1]. [more]

T First neutrino mass results from KATRIN (Dr. Thierry Lasserre)

T First neutrino mass results from KATRIN
The KATRIN experiment is designed to directly probe the mass of neutrinos with a sensitivity of 0.2 eV (90% CL). KATRIN offers a model-independent approach based principally on the kinematics of tritium beta decay. [more]

Double feature: Bridging machine learning and quantum physics with tensor Networks (Dr. Ivan Glasser)

Double feature: Bridging machine learning and quantum physics with tensor Networks
Finding efficient representations of high-dimensional functions is a central problem in both machine learning and the simulation of quantum many-body systems. [more]
Recent experimental advancement in the field of optical cavity QED comprises two directions of development: A further reduction of the mode volumes of the resonators, as with the development of fiber-based Fabry-Perot cavities (FFPCs) [1], and an increase in the number of well-controlled modes the emitters can couple to [2, 3]. [more]

Quantum Computing NISQ Era and beyond

Quantum Computing NISQ Era and beyond
Noisy Intermediate-Scale Quantum (NISQ) technology will be available in the near future. Quantum computers with 50-100 qubits may be able to perform tasks which surpass the capabilities of today's classical digital computers, but noise in quantum gates will limit the size of quantum circuits that can be executed reliably [more]

Towards Highly Storage Efficiency of Optical Quantum Memory Based on Electromagnetically Induced Transparency Protocol

Towards Highly Storage Efficiency of Optical Quantum Memory Based on Electromagnetically Induced Transparency Protocol
Long-distance quantum communication based on quantum repeater protocol [more]

Probing dynamical properties of Fermi-Hubbard systems with a quantum gas microscope (Prof. Waseem Bakr)

Probing dynamical properties of Fermi-Hubbard systems with a quantum gas microscope
The normal state of high-temperature superconductors exhibits anomalous transport and spectral properties that are poorly understood. Cold atoms in optical lattices have been used to realize the celebrated Fermi-Hubbard model, widely believed to capture the essential physics of these materials. The recent development of fermionic quantum gas microscopes has enabled studying Hubbard systems with single-site resolution. Most studies have focused on probing equal-time spin and density correlations. [more]

Trapped ion optical clocks and tests of the equivalence principle (Dr. Ekkehard Peik)

Trapped ion optical clocks and tests of the equivalence principle
Optical clocks based on different atoms and ions with uncertainties in the low 10-18 range allow for frequency comparisons that can be used in tests of fundamental physics, like in quantitative tests of relativity and searches for violations of the equivalence principle. [more]

Laser-cooled molecules for quantum science and tests of fundamental physics (Prof. Michael Tarbutt)

Laser-cooled molecules for quantum science and tests of fundamental physics
Ultracold molecules can be used to test fundamental physics, simulate many-body quantum systems, process quantum information, and study ultracold chemistry. [more]

Probing our understanding of particle- and astrophysics with neutrons (Prof. Stephan Paul)

Probing our understanding of particle- and astrophysics with neutrons
Precision experiments probing the properties of neutrons and details of their decay can reveal important information for both particle and astrophysics. [more]

Passion extreme light (Prof. Gérard Mourou)

Passion extreme light
Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in black-holes. [more]

Automatic Differentiation of Tensor Expressions

Automatic Differentiation of Tensor Expressions
Automatic differentiation is a powerful tool that allows to compute derivatives not only of mathematical expressions but also of functions that are given as a computer program. [more]

Double Feature: Towards attosecond and femtosecond spectroscopy at extreme limits (Dr. Hanieh Fattahi)

Towards attosecond and femtosecond spectroscopy at extreme limits
This talk is devoted to modern methods for attosecond and femtosecond laser spectroscopy, with the special focus on applications that require extreme spatial resolution. [more]

Double Feature: High Precision Direct Frequency Comb Spectroscopy in UV (M.Sc. Alexey Grinin)

High Precision Direct Frequency Comb Spectroscopy in UV
In the last two decades frequency combs became an essential tool for spectroscopyexperiments around the world, allowing for simple and convenient referencing of laserswith dierent wavelengths to each other and to radio frequency standards [1]. A numberof other interesting applications in applied spectroscopy, astronomy, quantum informationand other elds are being investigated [2, 3]. [more]

Exploring matter-wave emission phenomena in optical lattices (Prof. Dominik Schneble)

Exploring matter-wave emission phenomena in optical lattices
The quantitative understanding of spontaneous emission harks back to the early days of QED, when in 1930 Weisskopf and Wigner, using Dirac's radiation theory, calculated the transition rate of an excited atom undergoing radiative decay. Their model, which describes the emission of a photon through coherent coupling of the atom's transition dipole moment to the continuum of vacuum modes, reflects the view that spontaneous emission into free space, driven by vacuum fluctuations, is inherently irreversible. [more]

Learning and artificial intelligence in the quantum domain (Prof. Hans Briegel)

Learning and artificial intelligence in the quantum domain
Quantum mechanics has changed the way we think about the scope and possibilities of information processing, and the foundations of computer science. [more]

Review procedures in Nature Photonics

Review procedures in Nature Photonics
Nature-branded journals (such as Nature, Nature Photonics, Nature Physics, etc.) are some of the most prestigious and important scientific publications in the world today. To maintain the quality and high impact factor of each journal, the editors rigorously select papers that provide conceptual or technological breakthrough according to stringent acceptance criteria and a unique reviewing process. [more]

Double Feature: Distillation of Single Photons based on Cavity QED (M.Sc. Severin Daiss)

Distillation of Single Photons based on Cavity QED
Custom-shaped single photons are an indispensable tool for many quantum communication applications. We distill them out of incoming optical pulses that are reflected from an atom-cavity system [1]. [more]

Double Feature: Geometry of variational manifolds and the Bose-Hubbard model (Dr. Lucas Hackl)

Geometry of variational manifolds and the Bose-Hubbard model
A key challenge in the theoretical study of quantum many body systems is to overcome the exponential growth of the Hilbert space with the system size. Many successful approaches are variational, i.e., they are based on choosing suitable families of states that capture key properties of the system. Prominent examples range from Gaussian states to matrix product states and tensor networks. [more]

From Precision Spectroscopy to Symmetry-Breaking Dynamics in Ion Coulomb Systems (PD Dr. Tanja Mehlstäubler)

From Precision Spectroscopy to Symmetry-Breaking Dynamics in Ion Coulomb Systems
Single trapped and laser-cooled ions in Paul traps allow for a high degree of control of atomic quantum systems. They are the basis for modern atomic clocks, quantum computers and quantum simulators. Our research aims to use ion Coulomb crystals, i.e. many-body systems with complex dynamics, for precision spectroscopy. This paves the way to novel optical frequency standards for applications such as relativistic geodesy and quantum simulators in which complex dynamics becomes accessible with atomic resolution. [more]

Table-top precision measurements to test fundamental physics: Measurements of the proton charge radius, the fine-structure constant and the electron electric dipole moment (Prof. Eric Hessels)

Table-top precision measurements to test fundamental physics: Measurements of the proton charge radius, the fine-structure constant and the electron electric dipole moment
Fundamental physics (including physics beyond the Standard Model) can be tested using table-top precision measurements. The talk will describe measurements of the size of the proton, the fine-structure constant and the electric dipole moment of the electron. Two recently completed measurements will be described. [more]

Non-perturbative Cavity QED (Prof. Peter Rabl)

Non-perturbative Cavity QED
In quantum optical systems the coupling between a single dipole and a single cavity mode is always much smaller than the absolute energy scales involved, which allows us to understand and model light-matter interactions in terms of well-defined atomic and photonic excitations. With recent advances in the field of circuit QED it is now possible to go beyond this well-established paradigm and enter a fully non-perturbative regime, where the coupling between a single artificial atom (e.g. a superconducting qubit) and a microwave photon exceeds the energy of the photon itself. Such conditions can be associated with an effective finestructure constant of order unity and in this talk I will give a brief introduction about the basics models and novel effects that govern the physics of light-matter interactions in this previously inaccessible regime. [more]

Optimized quantum photonics (Prof. Jelena Vuckovic)

Optimized quantum photonics
At the core of most quantum technologies, including quantum networks and quantum simulators, is the development of homogeneous, long lived qubits with excellent optical interfaces, and the development of high efficiency and robust optical interconnects for such qubits. To achieve this goal, we have been studying color centers in diamond (SiV, SnV) and silicon carbide (VSi in 4H SiC), in combination with novel fabrication techniques, and relying on the powerful and fast photonics inverse design approach that we have developed. [more]

SMT: Printing really small, really fast … … and what to do when you are at the end of your rope (Dr. Andreas Dorsel)

SMT: Printing really small, really fast … and what to do when you are at the end of your rope
This talk is intended to provide you with a solid notion of what can be achieved in nano-lithography today, what the present technical limitations are and what we consider at present fundamental boundaries of what may be possible in the future. Carl Zeiss SMT has been active in this field for more than 50 years and its history hence shows some of the technological milestones from the early beginnings of integrated circuits to present-day extreme integration allowing qualitatively new applications of micro- or rather nano-electronics. [more]

χ(2) Nanomaterials for Nonlinear Integrated Photonic Devices (Prof. Rachel Grange)

χ(2) Nanomaterials for Nonlinear Integrated Photonic Devices
Nonlinear optics is present in our daily life with many applications, e.g. light sources for microsurgery or green laser pointer. All of them use bulk materials such as glass fibres or crystals. Generating nonlinear effects from materials at the nanoscale can expand the applications to biology as imaging markers or sensors, and to optoelectronic integrated devices. However, nonlinear signals scale with the volume of a material. Therefore, finding nanostructured materials with high nonlinearities to avoid using high power and large interaction length is challenging. Here I will show several strategies to maximize nonlinear optical signals in nano-oxides with noncentrosymmetric crystalline structure and semiconductors. I will demonstrate how we enhance second-harmonic generation (SHG) by using the scattering properties of individual barium titanate (BaTiO3) nanoparticles1, and AlGaAs standing nanodisks2. Our results suggest that a strong increase of the SHG signal can be obtained without using plasmonics or hybrid nanostructures3 [more]

Quantum fluids of light in semiconductor lattices (Prof. Jacqueline Bloch)

Quantum fluids of light in semiconductor lattices
When confining photons in semiconductor lattices, it is possible to deeply modify their physical properties. Photons can behave as finite or even infinite mass particles, photons inherit topological properties and propagate along edge states without back scattering, photons can become superfluid and behave as interacting particles. These are just a few examples of properties that can be imprinted into fluids of light in semiconductor lattices. Such manipulation of light presents not only potential for applications in photonics, but is a great promise for fundamental studies. [more]

Connecting the Resource Theories of Purity and Coherence (Prof. Dagmar Bruss)

Connecting the Resource Theories of Purity and Coherence
The resource theory of quantum coherence studies the off-diagonal elements of a density matrix in a distinguished basis, whereas the resource theory of purity studies all deviations from the maximally mixed state. A direct connection between the two resource theories is established by identifying purity as the maximal coherence which is achievable by unitary operations. The states that saturate this maximum form a family of maximally coherent mixed states. Furthermore, purity bounds the maximal amount of entanglement and discord that can be generated by unitary operations, thus demonstrating that purity is the most elementary resource for quantum information processing. [more]

High Harmonic Generation Interferometry (Prof. Nirit Dudovich)

High Harmonic Generation Interferometry
Attosecond science is a young field of research that has rapidly evolved over the past decade. The progress in this field opened a door into a new area of research that allows one to observe multi-electron dynamics in in atoms, molecules and solids. One of the most exciting advances in atto-science is high harmonic generation (HHG) spectroscopy. It allows one to combine sub-Angstrom spatial with attosecond temporal resolution, holding the potential of resolving the structure of electronic wavefunctions as they evolve in time. [more]

Surface enhanced coherent Raman scattering (Prof. Eric Potma)

Surface enhanced coherent Raman scattering
Surface-enhanced Raman scattering (SERS) is a popular technique that makes it possible to boost the otherwise weak Raman effect to levels that allow single molecule detection. A coherent, nonlinear equivalent of single molecules SERS is highly attractive, because it would allow the use single vibrational quantum oscillators with a narrow line width for a host of interesting applications. The translation of SERS into the domain of coherent Raman spectroscopy (CRS) has, however, not been trivial. This presentation zooms into some of the recent accomplishments in this area, highlights single molecule CRS experiments and discusses the possibilities of performing single vibrational oscillator measurements without the use of nanoscale plasmonic antennae. [more]

Quantum Logic Spectroscopy with Trapped Ions (Prof. Dr. Dietrich Leibfried)

Quantum Logic Spectroscopy with Trapped Ions
Quantum logic spectroscopy uses the quantized motion of trapped charged particles as a means to indirectly control charged quantum systems and gain information on their properties. A highly controllable atomic "logic" ion indirectly helps to manipulate the system under study and to report information back to the experimenter. This allows for precise quantum control of charged systems that are hard or impossible to directly control with light fields, such as atomic ions without convenient laser cooling transitions, molecular ions or charged elementary particles such as the proton. This talk will introduce the basic ideas behind quantum logic spectroscopy and illustrate its power based on example experiments in the NIST Ion Storage Group. [more]

Synthesizing Light: New Tools, Wavelengths and Opportunities (Prof. Dr. Scott Diddams)

Synthesizing Light: New Tools, Wavelengths and Opportunities
Frequency synthesis is ubiquitous in all aspects of our modern technological society, with examples being found in wide ranging applications from computing, communications and navigation systems to sensors and scientific instrumentation. Historically, the generation and precise control of electromagnetic radiation has been confined to the radio frequency and microwave domains. How­ever, optical frequency combs, first introduced by Prof. T.W. Hänsch, dramatically expand the synthesis bandwidth to cover the entire terahertz and optical domains as well. [more]

Topology in finite‐temperature and non‐equilibrium systems (Prof. Michael Fleischhauer)

Topology in finite‐temperature and non‐equilibrium systems
Topological states of matter have fascinated physicists since a long time due to the exotic properties of elementary excitations and the topological protection of edge states and currents. The notion of topology is ususally associated with ground states of (many-body)-Hamiltonians. [more]

Cold and ultracold molecules for quantum information and particle physics (Prof. John Doyle)

Cold and ultracold molecules for quantum information and particle physics
Wide-ranging scientic applications have created growing interest in ultracold molecules. Heteronuclear bialkali molecules, assembled from ultracold atoms, enabled the study of long-range dipolar interactions and quantum-state-controlled chemistry, and recently have been brought to quantum degeneracy. Assembling such molecules one-byone in tweezers for quantum information applications is one exciting avenue of this work. [more]

Double Feature: One-dimensional superradiant photonic states for quantum information (Dr. Marti Perarnau)

One-dimensional superradiant photonic states for quantum information
Photonic states with large and fixed photon numbers, such as Fock states, are crucial in quantum technologies but remain an experimentally elusive resource. A potentially simple, deterministic and scalable way to generate these states consists of fully exciting N quantum emitters equally coupled to a common photonic reservoir, which leads to a collective decay known as Dicke superradiance. The emitted N-photon wavepacket turns out to be a highly entangled multimode state, which makes its characterisation challenging, and its potential for quantum information an open question. In this talk, after reviewing the basics of superradiance and 1d waveguide QED, I will show that Dicke superradiant states have a high quantum Fisher information (achieving Heisenberg scaling), implying they enable quantum-enhanced metrology. Then, I will discuss possible effective descriptions of such states, which would allow a clean understanding of their properties. [more]

Double Feature: Interacting polar molecules in a spin-decoupled magic trap (Frauke Seeßelberg)

Interacting polar molecules in a spin-decoupled magic trap
Interacting particles with long coherence times are a key ingredient for entanglement generation and quantum engineering. Ultracold polar molecules are promising candidates due to their strong and tunable dipolar interactions as well as their long single-particle lifetimes. They possess many internal degrees of freedom that can be utilized in quantum simulation. Particularly appealing are superpositions of rotational states because they readily give rise to strong, long-range dipolar interactions. In this talk I will introduce a novel trapping technique for rotating polar molecules, nuclear spin-decoupled magic trapping. With this technique we achieve very low single-particle dephasing rates for our fermionic NaK molecules. These allow us not only to obtain record rotational spin coherence times but also to directly observe dipolar interactions in the molecular gas. This paves the way for fascinating future experiments with ultracold polar molecules. [more]

Double Feature: The ATLAS laser: from Terrawatt to Petawatt and from MPQ to CALA (Prof. Stefan Karsch)

The ATLAS laser: from Terrawatt to Petawatt and from MPQ to CALA
Abstract will follow shortly... [more]
Schrödinger's famous cat Gedankenexperiment investigates how the laws of quantum mechanics extend into the macroscopic realm. An experimentally accessible model system in quantum optics is the superposition of two well-distinguishable coherent states - a so-called "cat state" - with a tunable degree of macroscopicity. Applying a high-finesse cavity we demonstrate a new method to create flying optical cat states. They are entangled to a single trapped atom, much like Schrödinger's original cat. I show control over various degrees of freedom of the cat states, which is a great asset for their potential application to continuous-variable quantum computing. [more]

Quantum optics using atomic arrays (Prof. Dr. Darrick Chang)

Ensembles of atoms or other quantum emitters are envisioned to be an important component of quantum applications, ranging from quantum memories for light to photon-photon gates to metrology. It has historically been an outstanding challenge to exactly solve for the quantum dynamics of an optical field as it propagates through and interacts with an ensemble. The standard axiomatic approach is to use the one-dimensional Maxwell-Bloch equations, which assume that excited atoms emit independently into unwanted directions. This ignores the wave interference of the emitted light, which depends on correlations between the atoms. [more]
Finding efficient representations of high-dimensional functions is a central problem in both machine learning and the simulation of quantum many-body systems. In this talk I will discuss the relationship between these two fields of research using the framework of tensor networks, which have been invented independently in physics and computer science. [more]
In 1938 Petr Kapitza, investigating properties of the low temperature phase of liquid 4He, discovered that viscosity of the liquid is more than 104 times smaller, than that of all known liquids. Kapitza concluded, that the liquid is in a new state of matter, a “superfluid”, which to some extend analogous to superconductors. Landau (1941) explained the phenomenon and predicted several its unusual properties. It occurs, that in a superfluid in any point of space at finite temperatures simultaneously exists two flow with different velocities. One is “normal” and has finite viscosity and the second one is “superfluid”, which viscosity is exactly zero. This results in presence of two type of sound, which were discovered experimentally in 1946. [more]
Optical microscopy has been a fundamental tool to life science and materials science since its invention in the 17th century. [more]

Deciphering complex quantum systems (Prof. A. Buchleitner)

Not many ingredients are needed for a quantum system to turn complex, with the helium atom as the arguably most elementary example. [more]

Rotating molecules and fundamental constants (Prof. S. Schiller)

Molecules provide exciting opportunities for precision measurements - significantly extending those offered by atoms. [more]

Imaging in Biology and Biomedicine (Prof.Steven Chu)

In recent years, new imaging probes such as green fluorescent proteins, optical tweezers, single molecule FRET and super-resolution microscopy are having a profound impact on biological sciences. [more]

Precision spectroscopic measurements in H2, H2+, He2 and He2+(Prof. Merkt)

Few-electron molecules represent attractive systems for precision spectroscopy because their properties can be calculated with extraordinary accuracy by ab initio quantum-chemical methods. [more]

Combs and isotopic customization for trapped ion quantum computing (Prof. W. Campbell)

Since ions bind their valence electrons tightly, the light needed to work with them is often in the UV part of the spectrum, where laser light is difficult to produce and manage. [more]

Molecular spectroscopy with laser frequency combs (Dr. N. Picqué)

Almost twenty years ago, optical frequency combs – spectra made of millions of phase-coherent evenly spaced narrow laser lines – have revolutionized time and frequency measurements. [more]

How to count one photon and get a result of 1000 (Prof. A. Steinberg)

I will present our recent experimental work using electromagnetically induced transparency in laser-cooled atoms to measure the nonlinear phase shift created by a single post-selected photon, and its enhancement through "weak-value amplification." [more]

Correlations of a quantum system in real and momentum space (Prof. S. Jochim)

The properties of a many body system are encoded in correlations between the particles. [more]
Colloquium on the Occasion of Prof. Dr. Karl-Ludwig Kompa's 80th Birthday! Following please find detailed information: [more]

Coupling spin and orbital dynamics with quantum light (Prof. D. Stamper-Kurn)

A trapped atomic gas within an optical resonator serves as both a mechanical oscillator and a spin oscillator, represented by the collective degrees of freedom of the gas. [more]

Label-free tissue classification by FTIR- and QCL-based IR-imaging (Prof. K. Gerwert)

Infrared imaging in combination with bioinformatics is an emerging tool for label-free, non-invasive annotation of tissue, cells, and body fluids. [more]

Connecting quantum systems through optimized photonics (Prof. J. Vuckovic)

Semiconductor quantum dot in cavity has been the workhorse of solid-state quantum optics, enabling many exciting demonstrations such as photon blockade, and some of the best quantum light sources and spin-photon interfaces. [more]

Ultrafast Transmission Electron Microscopy with High-coherence Electron Beams (Prof. C. Ropers)

Ultrafast Transmission Electron Microscopy (UTEM) is a powerful technique to study structural and electronic dynamics on the nanoscale. [more]

Atomic giants in a new light: Emerging photon interactions from highly excited Rydberg atoms (Prof. T. Pohl)

The combination of electromagnetically induced transparency (EIT) and strongly interacting Rydberg states in cold atomic gases has opened up new routes towards achieving few-photon optical nonlinearities. [more]

Quantum many-body dynamics under continuous observation (Prof. M. Ueda)

Quantum gas microscopy has revolutionalized our approach to quantum many-body systems where atoms trapped in an optical lattice can be observed in real time at the single-particle level. [more]
This talk will present our on-going effort to control the dipole-dipole interaction between cold Rydberg atoms in order to implement spin Hamiltonians that may be useful for quantum simulation of condensed matter problems. [more]

Prospects for a quantum electro-optic interface via micromechanical motion (Prof. C. Regal)

Superconducting qubits have become a powerful resource for the creation of arbitrary quantum states. [more]

Making quantum liquids from quantum gases (Prof. L. Tarruell)

Self-bound states appear in contexts as diverse as solitary waves in channels, optical solitons in non-linear media and liquid droplets. [more]
Since the early days of quantum mechanics, understanding how statistical ensembles arise from the unitary time evolution of an isolated quantum system has been a fascinating problem. [more]

Magnonic macroscopic quantum states and supercurrents (Prof. B. Hillebrands)

Finding new ways for fast and efficient processing and transfer of data is one the most challenging tasks nowadays. [more]
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Optically Trapping and Isolating Ions for Seconds (Prof. T. Schätz)

Isolating ions and atoms from the environment is essential for experiments, especially if we aim to study quantum effects. [more]

Convex Optimization Methods for Image-based 3D Reconstruction (Prof. D. Cremers)

The reconstruction of the 3D world from a moving camera is among the central challenges in computer vision. [more]

An Einsteinian Analogy Sheds Light on Light (Prof. D. Hofstadter)

Where does deep insight in physics come from? For those who view physics as a highly rational science grounded in strict mathematical deduction, it is tempting to think that great physics comes only from the purest and most precise of reasoning, following ironclad laws of thought that compel the clear mind completely rigidly. [more]

Status and prospects of fiber lasers and amplifiers (Prof. A. Tünnermann)

In the past years rare-earth-doped fiber lasers have emerged as an attractive and power scalable solid-state laser concept due to the outstanding thermo-optical properties of an actively doped fiber. [more]

Brillouin-based light storage in a photonic circuit (Dr. B. Stiller)

Brillouin scattering is a fundamental nonlinear opto-acoustic interaction present in optical fibres and other waveguides with important implications in fields ranging from modern telecommunication networks, signal processing and smart optical sensors. [more]

Subcycle quantum physics (Prof. R. Huber)

Atomically strong light pulses in the terahertz window of the electromagnetic spectrum form a unique toolbox to trace and control electronic and ionic quantum motion faster than a cycle of light. [more]

Fundamental Physics with (weird) Magnetic Resonance (Prof. D. Budker)

I will discuss the ongoing experiments (CASPEr and GNOME) searching for ultralight galactic dark matter using magnetic-resonance techniques and a new approach to measuring parity violation in chiral molecular systems. [more]

Optical Atomic Clocks: From Laboratory Experiments to International Time Keeping (Dr. H. Margolis)

Optical atomic clocks based on laser-cooled atoms or single trapped ions have made rapid progress over the past few years, with the most advanced now having reached levels of stability and uncertainty that significantly surpass the performance of caesium primary frequency standards. [more]

Are we quantum computers, or merely clever robots? (Prof. M. Fisher)

Of course quantum information processing is not possible in the warm wet brain. There is, however, one \loophole" - oered by nuclear spins - that must be closed before acknowledging that we are merely clever robots. [more]
Generic, clean quantum many-body systems approach a thermal equilibrium after a long time evolution. In order to reach a global equilibrium, conserved quantities have to be transported across the whole system which is a rather slow process governed by diffusion. [more]

Quantum Measurements on Trapped Ions (Prof. J. Home)

Measurement as defined in quantum physics rarely corresponds to what is performed in the laboratory. [more]

Manipulating nuclei with laser light: the quest of Thorium-229 (Prof. T. Schumm)

The radio isotope Thorium-229 is expected to present a remarkably low-energy excited (isomer) state of the nucleus which is expected around 7.8(5) eV. [more]
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Quantum optics with trapped ions – from single ion heat engines to ions in vortex laser fields (Prof. F. Schmidt-Kaler)

Trapped single ions and ion crystal exhibit excellent control of the internal spin– and the external motional-degree of freedom. Multi-particle quantum entangled states are generated with high fidelity in view of a future quantum computer with trapped ions. [more]

The Alchemy of Vacuum - Hybridizing Light and Matter (Prof. T. Ebbesen)

Strong coupling of light and matter can give rise to a multitude of exciting physical effects through the formation of hybrid light-matter states. [more]
Computer simulations that predict the light-induced change in the physical and chemical properties of complex systems, molecules, nanostructures and solids usually ignore the quantum nature of light. [more]

Genome editing and the CRISPR/cas revolution (Prof. K. Förstemann)

I will present the origins of the prokaryotic (i.e. bacteria and archaea) CRISPR/cas systems, then describe how one particular variant (Streptococcus pyogenes cas9) has been adapted and optimized for use in eukaryotic cells. [more]

Potential Energy Surfaces and Berry Phases beyond the Born-Oppenheimer Approximation (Prof. E. Gross)

The starting point of essentially all modern electronic-structure techniques is the Born-Oppenheimer approximation. It not only makes calculations feasible, it also provides us with an intuitive picture of chemical reactions. [more]
Recent remarkable experimental progress in ‘circuit QED’ now allows realization of extremely strong dispersive coupling between superconducting qubits and microwave photons in resonators. [more]
Molecular systems that can be remotely controlled by light are gaining increasing importance in bio-sciences. High spatial and temporal precision is achievable with short laser pulses and in principle there are three approaches for light regulation. [more]
Controlling the interaction of light and matter is the basis for diverse applications ranging from light technology to quantum information processing. Nowadays, many of these applications are based on nanophotonic structures. [more]
Microoptics has a plethora of applications, ranging from miniature endoscopes in hospitals to beam shaping or imaging. 3D printing with a femtosecond laser and two-photon polymerization allows for manufacturing optical elements directly after their design with an optical CAD program on a computer, with a resolution better than 100 nm and a high accuracy and reproducibility. [more]

Searching for dark fields with atom interferometry (Prof. P. Hamilton)

One of the great mysteries of modern physics is the identity of nearly 95% of our Universe, which has been labelled as dark matter and dark energy. The high precision of atom interferometry gives a new way to explore this mystery. [more]
I plan to start this presentation with an overview of our work over the past decade on the efficient coupling of light and single quantum emitters, leading to the single-photon communication of two individual molecules at long distances [1]. [more]
Trapped atomic ions are a well-advanced physical system for quantum information science (QIS). QIS is meant to encompass the quest for a specialized, or even universal processor for quantum information, the investigation of fundamental questions of quantum physics, as well as applications of techniques emanating from these investigations to other fields, for example, precision spectroscopy and sensing. [more]
The field of thermodynamics is one of the crown jewels of classical physics. However, only comparatively recently, due to the advent of experiments in cold atomic systems with long coherence times, has our detailed understanding of its connection to quantum statistical mechanics seen remarkable progress. [more]
Ultracold quantum gases are usually well isolated from the environment. This allows for the study of ground state properties and unitary dynamics of many-body quantum systems under almost ideal conditions. [more]
The controlof polaritons are at the heart of nano-photonics and opto-electronics. Two-dimensional materials have emerged as a toolbox for in-situ control of awide range of polaritons: plasmons, excitons and phonons. [more]
Bose-Einstein condensation has been observed with cold atomic gases, quasiparticles in solid state systems as polaritons, and more recently with photons in a dye-filled optical microcavity. [more]
On September 14, 2015 the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a coincident signal conforming to the gravitational waveform expected from the merger of two massive, compact objects. [more]
The precision of any measurement is limited by quantum mechanics. Yet, in practice, hardly any measurement reaches its quantum limits. This is because dephasing typically influences measurement device, rendering their sensitivity below its physical limits. [more]
The propagation of light in inhomogeneous media, and in particular in biological tissues, results in wavefront distortions and scattering which impose major limitations in many applications, from microscopy to nanosurgery. [more]
Magnetization manipulation is an indispensable tool for both basic and applied research. I will discuss some of the knobs to tune dynamics at ultrafast time scales. [more]
One aspect of metrology, the science of measurement, is the exploration of the ultimate precision limit. It is known for quite some time that the new possibilities in quantum mechanics allow the surpassing of the ultimate classical precision limit given by counting statistics. [more]
Future quantum networks will allow the secure distribution of encryption keys over extended distances, blind quantum computing, and networked quantum computers and atomic clocks. [more]
The beauty of topological materials is that their electronic properties can be essentially described by integer topological invariants associated with their band structures.  [more]
Synthetic ladders realized with one-dimensional alkaline-earth(-like) fermionic gases and subject to a gauge field represent a promising environment for the investigation of quantum Hall physics with ultracold atoms. [more]
The design of fundamental optical components such as lenses, gratings, and holograms has remained essentially unchanged for at least fifty years, relying on textbook refractive and diffractive optics. [more]
Device-independent quantum information processing represents a new framework for quantum information applications in which devices are just seen as quantum black boxes processing classical information. [more]

Entanglement of Complex Quantum Systems (Prof. N. Schuch)

Complex quantum systems exhibit a variety of unconventional phenomena, such as protected quantized edge currents or excitations with non-trivial statistics.  [more]
Attosecond pulses are generated by electrons that are extracted from a quantum system by an intense light pulse and travel through the continuum. [more]
There has been an explosion of new imaging technologies in biology that include photo-activation localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM), and stimulated emission depletion (STED), structured illumination, and adaptive optics are revolutionizing optical microscopy. [more]
I will present recent work realizing topological phases of photons. [more]
Ultrafast time-resolved spectroscopy, and in particular its extension to multidimensional techniques, can tell us a lot about solvation dynamics, structural dynamics and energy transfer processes of solution phase molecular systems. [more]
Organic semiconductors with conjugated electron system are currently intensively investigated for (opto-) electronics. [more]
Hundred years after General Relativity:  Was Einstein right? [more]
Quantum mechanics is a foundation of physics, chemistry and materials science.  Still, there is an ongoing debate about the emergence of the classical, macroscopic world from the well-understood microscopic world of quantum mechanics.  [more]
Understanding the behavior of interacting electrons in solids or liquids is at the heart of modern quantum science and necessary for technological advances. [more]
We review the recent experimental progress on the use of quantum dots coupled to photonic-crystal waveguides [1]. [more]
Modern atomism evolved on the basis of observations of matter’s macroscopic features. [more]
Recent progress in establishing an extreme time-domain approach to condensed-matter physics and quantum optics is presented. [more]
The spectrum of molecular hydrogen H2 can be measured in the laboratory to very high precision using advanced laser and molecular beam techniques, as well as frequency-comb based calibration. [more]
The optoelectronic response of two-dimensional (2D) crystals, such as graphene and transition metal dichalcogenides (TMDs), is currently subject to intensive investigations.  [more]
In the talk I will review recent results on the (un-)decidability of problems in quantum many-body physics and quantum information theory. [more]
This talk will give a short overview of the latest insights into the promises and pitfalls of a diverse workforce on employee outcomes like respectful interactions at work, cooperation, creativity and conflict at work. [more]
In a recent workshop we tried to answer the very interesting question: “Attosecond science – what will it take to observe processes ‘in real time’?” [1]. [more]
It is more than 100 years since the battle began to determine the correct form of the momentum of light inside a material medium. [more]
A system of ultracold atoms in an optical lattice is an ideal quantum simulator of a strongly correlated quantum many-body system and also a topological quantum system due to the high-controllability of system parameters. [more]
Progress in physics and quantum information science motivates much recent study of the behavior of extensively-entangled many-body quantum systems fully isolated from their environment, and thus undergoing unitary time evolution. [more]
Many light-induced processes in biomolecules, such as energy relaxation, energy/charge transfer and conformational changes, occur on ultrafast timescales, ranging from 10-14 to 10-13 s. [more]
Ultracold atoms on optical lattices form a versatile platform for studying many-body physics, with the potential of addressing some of the most important issues in strongly correlated matter. [more]
Extensive research in Nano-optics over the last decade has made possible controlling optical fields on the nanometer scale. Such concentration of light, well below the limit of diffraction, opens plenty of new routes towards enhanced interaction with tiny amounts of matter down to the single molecule/atom level. [more]
UV-irradiation by sun-light imposes a permanent menace to live on earth. UV-radiation causes serious loss of genetic information. [more]
ESA's Planck mission is the third generation satellite to study the Cosmic Microwave Background. [more]
There has been a long-standing quest to observe chemical reactions at low temperatures where reaction rates and pathways are governed by quantum mechanical effects or long range interactions. [more]
We study the ground state properties of the simplest quantum link model undergoing a SU(2) lattice gauge invariance, in one spatial dimension. [more]
I will give an introduction to the AdS/CFT correspondence and its generalization for non-experts. [more]
Many applications of quantum information rely on the potentiality of quantum systems to be correlated. For pure states, these correlations coincide with entanglement. [more]
Quantum communications is the art of transferring a quantum state from one location to a distant one. [more]
Molecules cooled to ultralow temperatures provide fundamental new insights to strongly correlated quantum systems, molecular interactions and chemistry in the quantum regime, and precision measurement. [more]
With the announcement of the discovery of a Higgs-like particle in July 2012 by the two general-purpose experiments ATLAS and CMS at the Large Hadron Collider (LHC) at CERN particle physics has entered a new era. [more]
Achieving optical nonlinear interactions at the level of single photons has been the subject of extensive research in the last couple of decades. [more]
This talk will describe some of the physics challenges that arise in the pursuit of quantum information technology. [more]
Quantum systems can reach unusual states of matter when they are driven by fast time-periodic modulations. [more]
Multiparticle entangled quantum states, required as a resource in quantum-enhanced metrology and quantum computing, are usually generated by unitary operations exclusively, while carefully shielding the system from any coupling to the environment. [more]
Many body localization and the breakdown of ergodicity in quantum systems [more]
Time-resolved electron diffraction and electron deflectometry using femtosecond electron pulses are useful techniques for observing ultrafast changes in the atomic-scale structure of matter and in the electromagnetic fields near matter during physical phenomena. [more]
The physical properties of condensed matter are often caused by ultrafast phenomena involving low-energy elementary excitations, such as lattice vibrations, spin pre­ces­sion, plasmons, or superconducting energy gaps. [more]
"High repetition rate parametric oscillators and amplifiers (OPO, OPA) for very short optical pulses profit from the advancement in high power solid-state pump laser technology. In this talk, topical OPA and OPO systems with multi-Watt average powers and sub-10 fs pulses are presented. Employing (2+1)D nonlinear propagation simulation it is possible to reconstruct the complex spatio-temporal and spectral evolution of the interacting light fields and their mixing products in the gain crystals.Regarding the shortest pulses, challenges in pulse characterization and pulse shaping are addressed as well as some fundamental questions regarding the femtosecond response time of nonlinear phenomena." [more]
"The circuit-to-Hamiltonian construction translates dynamics (a quantum circuit and its output) into statics (the groundstate of a circuit Hamiltonian) by explicitly defining a quantum register for a clock. The standard Feynman-Kitaev construction uses one global clock for all qubits while we consider a different construction in which a clock is assigned to each interacting qubit. This makes it possible to capture the spatio-temporal structure of the original quantum circuit into features of the circuit Hamiltonian. The construction is inspired by the original two-dimensional interacting fermionic model (see this http URL) We prove that for one-dimensional quantum circuits the gap of the circuit Hamiltonian is appropriately lower-bounded so that the applications of this construction for QMA (and partially for quantum adiabatic computation) go through. For one-dimensional quantum circuits, the dynamics generated by the circuit Hamiltonian corresponds to diffusion of a string around the torus. See the paper at http://arxiv.org/abs/1311.6101" [more]
"Superconducting quantum computing is now at an important crossroad, where “proof of concept” experiments involving small numbers of qubits can be transitioned to more challenging and systematic approaches that could actually lead to building a quantum computer. Our optimism is based on two recent developments: a new hardware architecture for error detection based on “surface codes”, and recent improvements in the coherence of superconducting qubits. I will explain how the surface code is a major advance for quantum computing, as it allows one to use qubits with realistic fidelities, and has a connection architecture that is compatible with integrated circuit technology. Additionally, the surface code allows quantum error detection to be understood using simple principles. I will also discuss how the hardware characteristics of superconducting qubits map into this architecture, and review recent results that show gate errors can be reduced to below that needed for the error detection threshold." [more]
"Recent experimental investigations of excitonic transport in photosynthesis indicate that quantum coherence can play an important role in enhancing energy transport in photosynthetic complexes.This talk presents a general theory of optimizing energy transport in photosynthesis and in artificial systems.Optimal energy transport takes place at the point where the timescales for dynamic and static disorder converge, a phenomenon called the quantum Goldilocks effect." [more]
"Recently, atom-like impurities in diamond (colour centres) have emerged as an exceptional system for quantum physics in solid state. In this talk I will discuss recent developments transforming quantum control tools into quantum technologies based on single colour centres. Specially, realization of quantum optical interface between spins and photons and scalable quantum registers in diamond will be presented. New applications of diamond qubits involving nanoscale magnetic resonance and force measurements will be shown. I will discuss single spin NMR paving the way to ultrasensitive MRI and structure determination of single biomolecules. The detection of proteins using nanodiamond sensors will be presented. I will also highlight future directions of research including combination of quantum error correction and sensing protocols and quantum enabled sensing and imaging in living cells." [more]
"For almost two decades harmonically-trapped ultracold atomic gases have been used with great success to study fundamental many-body physics in a flexible experimental setting. Recently, we achieved the first atomic Bose-Einstein condensate in an essentially uniform potential of an optical-box trap [1]. This opens unprecedented possibilities for closer connections with other many-body systems and the textbook models that rely on the translational symmetry of the system. I will present our first experiments on this new system, including the first observation of the quantum Joule-Thomson effect [2], which was theoretically predicted more than 70 years ago.[1] A. L. Gaunt et al., Phys. Rev. Lett. 110, 200406 (2013)[2] T. F. Schmidutz et al., Phys. Rev. Lett. 112, 040403 (2014)" [more]
"The comparison between experimental values of transition frequencies in atomic hydrogen, the most simple atomic system, and the corresponding theoretical predictions provides stringent tests of bound state QED calculations. For more than a decade, this comparison has been limited by insufficient knowledge about the size of the proton, strictly speaking its r.m.s. charge radius. In 2010, a value for the proton size has been extracted from laser spectroscopy of muonic hydrogen which is ten times more accurate than any previous determination. However, this value deviates from the value found by precision spectroscopy of regular hydrogen by four combined standard deviations. An even larger inconsistency of 7σ is obtained when including electron-proton scattering data. The muonic hydrogen value has been confirmed and improved in 2013 while the source of the discrepancy, referred to as the ‘proton size puzzle’, remains unclear.In this talk, we report on a new precision spectroscopy experiment, aiming to shed light on the regular hydrogen part of the puzzle: In contrast to previous high resolution experiments probing transition frequencies between the meta-stable 2S state and a higher lying nL state (n = 3, 4, 6, 8, 12, L = S, P, D), our measurement of the 2S – 4P transition frequency is the first experiment being performed on a cryogenic beam of hydrogen atoms in the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present preliminary results obtained so far." [more]
"Strongly correlated quantum many-body systems display many fascinating phenomena, but they are difficult to describe due to the huge dimension of the involved Hilbert spaces. For this reason, models that can be treated fully or partially by analytical tools are valuable guides for understanding the physics underlying the phenomena. A prominent example is the fractional quantum Hall effect (FQHE), for which much information has been obtained by use of trial wave functions. In the talk, I will present a method to construct a quite broad class of many-body models, for which both the state and Hamiltonian are known analytically. One family of states within this class constitutes FQHE-like lattice states. The FQHE was originally discovered in semiconductor devices, but in the last few years much effort has been put into investigating the possibilities for obtaining FQHE-like states in lattice systems. One motivation for this is the perspectives for simulating FQHE physics under highly controllable conditions, e.g. in ultracold atoms or molecules in optical lattices. The typical strategy for obtaining FQHE-like lattice states is to mimic the solid state setting, but the above mentioned family of models provides an alternative. It is also possible to construct critical models, which allows us to study phase transitions." [more]
"Non-alkali-metal atoms have recently proved to be fascinating systems to explore novel lands in ultracold quantum physics. Here, we present recent results with ultracold dipolar gases of erbium atoms. As a consequence of the strong dipole-dipole interaction and of the large anisotropy in the dispersion potential, Er shows a spectacularly high number of Fano-Feshbach resonances both in the fermionic and bosonic isotopes. The complex Er scattering behavior escapes to traditional scattering models and requires novel approaches based on statistical analysis. Following the powerful toolset provided by Random-Matrix theory, we elucidate the chaotic nature of the scattering. Finally, we report on the first degenerate Fermi gas of Er, which is realized by direct cooling of identical fermions based on dipole-dipole interaction." [more]
"Optical cavities provide a coherent interface between light and matter that can be used to link remote quantum systems. With such an interface, quantum information can be mapped from a single atom onto a photon for long-distance transport, and an atom can be entangled with a cavity photon as a resource for teleportation. However, in a future quantum network, it would be advantageous for each cavity to contain multiple atoms. These atoms could be used for local quantum information processing, error correction between network nodes, and improved quantum memories, among other tasks.I will describe the coupling of two calcium ions to the mode of a high-finesse optical cavity. When both ions are coupled with near-maximum strength to the cavity, we entangle the ions with one another, heralded by the measurement of two orthogonally polarized photons. Applications of entangled ions in a cavity will be discussed, in the context of both quantum information tasks and the investigation of open quantum systems. In particular, I will present recent measurements of enhanced quantum state transfer from a superradiant two-ion state." [more]
"On a fundamental level, chemical reactions and condensed-matter transformations are defined by the motion of atoms and electrons from initial to final conformations, typically along a complex reaction path involving ultrasmall and ultrafast dimensions. Here we report on our progress towards a full visualization of structural dynamics in space and time. After laser excitation, ultrashort electron pulses at 30-100 keV are diffracted with time delays and provide a pump-probe sequence of structural snapshots with atomic resolution. We solve the most essential problem for time resolution, Coulomb repulsion, by using single-electron pulses in combination with a microwave compressor. The so achieved 12-fs electron pulses (rms) are among the shortest worldwide and now provide access to the fastest phonons or molecular modes with atomic resolution. In order to further advance towards the regime of purely electronic motion, we apply the microwave compressor’s time-dependent fields for reshaping the single-electron phase space from the temporal into the energetic domain. The achievable pulse durations are shorter than optical light cycles, promising direct diffraction access to electronic motion with a resolution of picometers and attoseconds. We report our first proof-of-principle results and reflect on what discoveries we may expect to see." [more]
"All-optical switching is a technique in which a gate light pulse changes the transmission of a target light pulse without the detour via electronic signal processing. We take this to the quantum regime, where the incoming gate light pulse contains only one photon on average. The gate pulse is stored as a Rydberg excitation in an ultracold atomic gas using electromagnetically induced transparency. Rydberg blockade suppresses the transmission of the subsequent target pulse. Finally, the stored gate photon can be retrieved. A retrieved photon heralds successful storage. The corresponding postselected subensemble shows an extinction of 0.05. Recent improvements of our experiment made it possible to observe a gain of 20. The single-photon switch offers many interesting perspectives ranging from quantum communication to quantum information processing." [more]
"This talk discusses the ideas and goals of the Energiewende, which aims at successively decarbonizing all of the german energy supply systems, but suffers from patchwork, wild exaggerations, cost explosions, and true pitfalls due to the construction of the European Climate Program.After a general overview we have a closer look at the electrical power generation and distribution, which is strongly affected by the Energiewende. We evaluate the consequences of the intermittent power production by wind turbines and photovoltaic panels, the dynamics of the present conventional power plants and the need and potential of present or future storage systems. The role of hydrogen and synthetic fuels as a form of chemical energy storage is discussed." [more]
How did the field of quantum information begin? To my mind, it was when John Wheeler formed his little group of students and postdocs at the University of Texas in the early 1980s. David Deutsch, Benjamin Schumacher, William Wootters, and Wojciech Zurek were all there. Even Richard Feynman visited once. It was because Wheeler had a single-minded purpose. To every student who walked into his office---even the first year undergraduate---Wheeler would implore: “Give an information theoretic derivation of quantum theory!” He saw that as the only way to get a real understanding of “the quantum” (as he called it). In this talk, I will outline how Wheeler’s old hope is still giving technical fruit in the context of Quantum Bayesianism (or QBism). Particularly, that context points naturally to a study of a mysterious structure in Hilbert space called the Symmetric Information Complete (SIC) quantum measurement. When these structures exist (and it seems they do for all finite dimensions, though no one has yet proven it!) they give a very clean way of writing the Born rule in purely probabilistic terms. This gives the hope that all the mathematical structure of quantum theory might be derivable from one very basic physical scenario. It’s not the double-slit experiment that Feynman argued for in his Feynman Lectures, but one might still appeal to his foresight and hope, “In reality, [this new scenario] contains the only mystery [of quantum mechanics].” [more]
Gauge fields are ubiquitous in Physics. For example, in the context of high energy physics, they are the fundamental carrier of forces; while in condensed matter systems the associated physical fields (electrical and magnetic) are essential in creating and understanding many-body phenomena. These fields can depend on internal — spin — degrees of freedom, and in material systems these spin-dependent gauge fields are often manifest as spin-orbit coupling (SOC, but more correctly spin-crystal momentum coupling).Here I present our experimental work synthesizing SOC for ultracold neutral atoms. I will first show how we use the light-matter interaction to engineer gauge terms in the atomic Hamiltonian, and then how to make these depend on spin. Using such techniques, we created SOC in a pseudo-spin 1/2 Bose gas and observed a previously unexpected quantum phase transition. I will conclude by showing the observed phase diagram of a spin-1 spin-orbit coupled Bose gas: a context without analog in traditional condensed matter systems. [more]
Real-time control of electrons in the microcosm calls for electromagnetic forces confinable and tunable over sub-femtosecond time intervals. I will discuss how recent progress in lightwave technologies has enabled key steps towards this essential milestone in science and technology. With novel types of light synthesizers which can manipulate ultrawideband coherent radiation sources, spanning the visible and flanking spectral ranges, it is now possible to sculpt and trace the waveform of light with subcyclic precision opening up the route to attosecond photonics. We will focus on first representative applications that highlight the emerging capabilities. [more]
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