Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 33: Cavity QED, QED, and Spin-Boson Systems I

Q 33.1: Vortrag

Mittwoch, 4. März 2026, 14:30–14:45, P 4

Cavity-Induced Electronic Phases and Thermodynamics in Low-Dimensional Systems — •Valerii Kozin, Dmitry Miserev, Even Thingstad, Daniel Loss, and Jelena Klinovaja — Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland

We present our recent findings in the field of cavity quantum electrodynamics (QED). The talk consists of three parts. In the first part, we explore double quantum dots coupled to a cavity mode, highlighting cavity-induced quantum phase transitions (both continuous and discontinuous) arising from cavity-mediated and Coulomb interactions, which can produce cat states relevant for quantum computing. In the second part, we discuss a mesoscopic two-dimensional electron gas confined in a double quantum well and coupled to a uniform cavity mode. When the number of electrons participating in virtual intersubband transitions is large, the effective photonic potential develops many minima, each behaving as a nearly harmonic oscillator. The energy offsets of these minima determine their statistical weights, collectively leading to an additive correction to the system’s heat capacity. This correction exhibits a Schottky anomaly and a 0.5k_B plateau at low temperatures. In the final part, we examine the enhancement of superconductivity in a two-dimensional electron gas coupled to a cavity, where stronger coupling linearly increases the superconducting gap, potentially observable via scanning tunneling microscopy. Together, these results underscore the pivotal role of cavity fields in controlling electronic properties for quantum technologies.

Keywords: cavity QED; superconductivity; cat states; 2D systems; quantum phase transitions