Open system probes of many-body environments: Finite temperature effects

The effective dynamics of an open quantum system are uniquely determined by environmental correlation functions, with properties of the environment manifesting in both the magnitude and the time-dependence of the induced decoherence rates. Thus, non-Markovian dynamics can provide a powerful lens to probe non-trivial and correlated many-body environments. For instance, previous works have shown that the phase transition of a transverse-field Ising model (TFIM) may be diagnosed by measuring the degree of non-Markovianity of a single central spin. In part two of this two-part talk, we extend our master equation construction to consider a finite-temperature environment, thus generalizing the results of part one to any region in the temperature-magnetic field phase diagram of the TFIM. Quantifying the temperature-dependent non-Markovianity of the probe qubit via its spectrum [1], we find deviations from Markovian spectra both on ultraviolet and infrared frequency scales. We show that these non-Markovian signatures [2] can be deployed to map the direction of the renormalization group flow between fixed points in the many-body phase diagram.

[1] A. Keefe, N. Agarwal, A. Kamal. arXiv:2405.01722 (2024)

[2] B. Bowen, N. Agarwal, A. Kamal. arXiv:2403.18907 (2024)