MQT 2024

Impact of system-bath coupling on a quantum system's steady state

Janet Anders University of Potsdam and University of Exeter

The dynamical convergence to the Gibbs state is a standard assumption across much of classical and quantum thermodynamics. However, for nanoscale and quantum systems the interaction with their environment becomes non-negligible, andso-called mean force (Gibbs) states are the equilibrium states [1]. Their properties can be important whenever energy is exchanged on the nanoscale, from quantum chemistry to magnetism.

In this talk I will first provide analytical expressions for the mean force state [2] and then discuss the impacts of system-bath coupling for a few examples. These include the presence of steady state coherences [2] in the V-level system interacting with noisy electromagnetic fields [3], and the significant system-bath entanglement emerging when a spin couples to a more realistic 3D environment instead of the commonly studied 1D environment [4]. I will close with a full characterisation of the transition from ultraweak to ultrastrong coupling regime for the widely applicable spin-boson model [5].

[1] Trushechkin, Merkli, Cresser, Anders,AVS Quantum Sci. 4, 012301 (2022)

[2] Cresser, Anders, PRL 127, 250601 (2021)

[3] Tscherbul, Brumer, PRL 113, 113601 (2014)

[4] Hogg, Cerisola, Cresser, Horsley, Anders, Quantum 8, 1357 (2024)

[5] Cerisola, Berritta, Scali, Horsley, Cresser, Anders, NJP 26, 053032 (2024)