Seminars


Seminars

On an irregular basis various Special Seminars take place at the MPQ. The seminars are organized by scientists of our divisions, administration or staff representatives. The location will be announced with the event.
Location: Max Planck Institute of Quantum Optics

Special Seminar: "Multiphoton Kramers-Heisenberg Formula for Describing High-Harmonic Generation." (Prof. Sándor Varró)

Abstract. We discuss the question of how can one treat the laser-induced (or laser-assisted)high-order processes of electrons (bound or free) nonperturbatively, in such a way that boththe electron-atom interaction and the quantized nature of radiation be simultaneously takeninto account? An analytic method is proposed to answer this question in the generalframework of nonrelativistic quantum electrodynamics. As an application, a quantum opticalgeneralization of the strong-field Kramers-Heisenberg formula has been derived fordescribing high-harmonic generation (HHG). [more]
Precision measurements of the Rydberg spectra of H, He and H2 will be presented, which aim at determining their ionization energies and, in the case of H2, also the spin-rovibrational energy-level structure of H2+. These measurements are carried out for comparison with the results of first-principles calculations that include the treatment of finite-nuclear-size effects and relativistic and quantum-electrodynamics corrections up to high order in the fine-structure constant. [more]
The field of quantum computation heavily relies on the belief that quantum computation violates the extended Church Turing thesis, namely, that quantum many-body systems cannot be simulated by classical ones with only polynomial overhead. Importantly, we must ask: what experimental evidence do we have for this bold assumption? A major effort towards providing such evidence had concentrated on random quantum circuit sampling (RCS) as in the famous supremacy experiment by Google from 2019. I will describe a recent work with Gao, Landau, Liu and Vazirani in which we give a polynomial time classical algorithm for simulating such RCS experiments. Our algorithm gives strong evidence that RCS cannot be the basis for near term experimental evidence for scalable exponential quantum advantage. [more]
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