Qubit Heating Near a Hotspot

Abstract

Effective theories describing black hole exteriors contain many open-system features due to the large number of gapless degrees of freedom that lie beyond reach across the horizon. A simple solvable Caldeira-Leggett type model of a quantum field interacting within a small area with many unmeasured thermal degrees of freedom was recently proposed in arXiv:2106.09854 to provide a toy model of this kind of dynamics against which more complete black hole calculations might be compared. We here compute the response of a simple Unruh-DeWitt detector (or qubit) interacting with a massless quantum field φ coupled to such a hotspot. Our treatment differs from traditional treatments of Unruh-DeWitt detectors by using Open-EFT tools to reliably calculate the qubit's latetime behaviour. We use these tools to determine the efficiency with which the qubit thermalizes as a function of its proximity to the hotspot. We identify a Markovian regime in which thermalization does occur, though only for qubits closer to the hotspot than a characteristic distance scale set by the φ-hotspot coupling. We compute the thermalization time, and find that it varies inversely with the φ-qubit coupling strength in the standard way.

Quantum recoherence in the early universe

“…Master equations are commonly employed in cosmology to model the effect of additional degrees of freedom, treated as an environment, onto a given system [40,46,53,58,[61][62][63][64][106][107][108][109][110][111][112][113][114][115][116][117]. One of their appealing advantages is their ability to re-sum late-time secular effects [64,112,113,[118][119][120][121][122], hence to go beyond standard perturbation theory and implement non-perturbative resummations in cosmology. Note that the recoherence phenomenon being a manifestly non-Markovian feature, it cannot be modelled by an irreversible dynamical-map such as the Lindblad equation [123].…”

Entanglement Negativity in de Sitter Biverse from Stringy Axionic Bell Pair: An Analysis Using Bunch‐Davies Vacuum

“…It would be really good if we can study the open quantum system version of the present set up within the framework of quantum field theory of de Sitter space. [24,34,117,[146][147][148][149][150][151][152][153][154][155][156]…”