Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 48: Ultra-cold Atoms, Ions and BEC III (joint session A/Q)
Q 48.5: Talk
Thursday, March 14, 2024, 15:30–15:45, HS 1010
Josephson effect in a double-well potential and its generalization for finite temperatures — •Kateryna Korshynska1,2 and Sebastian Ulbricht2,3 — 1Department of Physics, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, Kyiv 01601, Ukraine — 2Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, D-38116 Braunschweig, Germany — 3Technische Universität Braunschweig, D-38106 Braunschweig, Germany
In modern cold atom physics the study of many-particle bosonic systems gives insight into fundamental quantum processes and lays the foundation for powerful tools in precision metrology. The quantum nature of a bosonic system manifests itself in the Josephson effect, when the particles are placed in a double-well potential. In this potential one can define time-dependent probabilities of a single particle to be in the left or the right well. From that we develop the description of a many-particle system in the regime of global coherence (BEC) and in the case when the system is partially non-coherent. Focusing on the latter case we address the changes in many-particle dynamics, giving rise to a generalization of Josephson equations, which describe the system in non-equilibrium at finite temperatures. In this regime they predict deviations from the standard Josephson effect, which become more pronounced for high temperatures and a small number of bosons. For low temperatures, moreover, we find that the amplitude of Josephson oscillations is restricted. This prediction can be used to test the principles of statistics of a many-particle quantum system.
Keywords: Josephson effect; double-well potential; finite temperature; degree of fragmentation; degree of condensation