Local coherence by thermalized intra-system coupling

TL;DR

This paper introduces a new method for generating quantum coherence in two-level systems through engineered interactions and collective effects, enhancing quantum sensing capabilities without complex system-bath engineering.

Contribution

It presents a novel approach to autonomous quantum coherence generation using engineered interactions and collective effects in thermalized two-level systems.

Findings

Maximum quantum coherence achieved surpassing traditional engineered system-bath coupling.

Coherence can be built using weaker, collective interactions with multiple systems.

Enhanced phase estimation accuracy in quantum sensing applications.

Abstract

Quantum superposition of energy eigenstates can appear autonomously in a single quantum two-level system coupled to a low-temperature thermal bath, if such coupling has a proper composite nature. We propose here a principally different and more feasible approach employing engineered interactions between two-level systems being thermalized into a global Gibbs state by weakly coupled thermal bath at temperature $T$. Therefore, in such case quantum coherence appears by a different mechanism, whereas the system-bath coupling does not have to be engineered. We demonstrate such autonomous coherence generation reaching maximum values of coherence. Moreover, it can be alternatively built up by using weaker but collective interaction with several two-level systems. This approach surpasses the coherence generated by the engineered system-bath coupling for comparable interaction strengths and directly reduces phase estimation error in quantum sensing. This represents a necessary step towards the autonomous quantum sensing.