Die Gastvorträge im Rahmen des MPQ-Kolloquiums finden von April bis Juli sowie von Oktober bis Januar jeweils dienstags um 14:30 Uhr statt. Verantaltungsort ist der Herbert-Walther-Hörsaal im Foyer des Max-Planck-Instituts für Quantenoptik.

Ansprechpartner für die wissenschaftliche Organisation:

Dr. Stephan Dürr und Dr. Thomas Udem

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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. [mehr]

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. [mehr]

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. [mehr]

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... [mehr]
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. [mehr]
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