Extraction of autonomous quantum coherences

TL;DR

This paper demonstrates that quantum coherence generated in a low-temperature environment can be extracted via weak coupling to an output system, with implications for experimental quantum technologies.

Contribution

It proves that coherence induced by a low-temperature environment is generally extractable through weak coupling, including in fermionic systems, expanding understanding of quantum resource management.

Findings

Coherence extraction is possible for spins, oscillators, and fields.

The process is effective across various temperatures and frequencies.

The results suggest new experimental avenues for quantum coherence utilization.

Abstract

Quantum coherence is an essential resource to gain advantage over classical physics and technology. Recently, it has been proposed that a low-temperature environment can induce quantum coherence of a spin without an external coherent pump. We address a critical question if such coherence is extractable by a weak coupling to an output system dynamically affecting back the spin-environment coupling. Describing the entire mechanism, we prove that such extraction is generically possible for output spins (also oscillators or fields) and, as well, in a fermionic analogue of such a process. We compare the internal spin coherence and output coherence over temperature and characteristic frequencies. The proposed optimal coherence extraction opens paths for the upcoming experimental tests with atomic and solid-state systems.