AQP -seminaari: On open quantum systems in thermal non-ergodic environments

Aalto Quantum Physics -seminaari (Nanotalo). Puhuja: Dr. Inés de Vega (Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-University Munich, Germany)

The dynamics of an open system crucially depends on the correlation function (CF) of its environment. In this talk, I will show that for thermal non-Harmonic environments the CF may not decay to zero but to a positive offset. Moreover, I will argue that such an offset may render the weak coupling and Lindblad equations inaccurate, and prevent the open system to thermalize. Finally, for a realistic environment of dye molecules, which may be considered as two-level fluctuators, we show the emergence of the offset by using matrix product states (MPS). Further, we discuss its link to a 1/f noise spectrum that, in contrast to previous models, extends to zero frequencies. Thus, our results may be relevant for describing dissipation in quantum technological devices like superconducting qubits, which are known to be affected by such noise.

[1] C. A. Parra-Murillo, M. Bramberger, C. Hubig, and I. de Vega. “Open quantum systems in thermal non-ergodic environments”, arXiv:1910.10496