Coherence thermometry using multipartite quantum systems

Abstract

Accurate temperature measurement at the quantum scale is becoming increasingly important for emerging quantum technologies, motivating the development of quantum thermometry based on quantum resources. In this work, we investigate how finite environmental temperature influences the coherence dynamics of multipartite quantum systems and examine whether quantum coherence can serve as a temperature sensitive observable. We consider a tripartite spin-boson model interacting with finite temperature non-Markovian dephasing environments under two physically distinct reservoir configurations, namely local and common environments. The dynamics of representative tripartite pure and mixed states are quantified using the relative entropy of coherence. Our results show that local dephasing produces a universal monotonic decay of coherence, with increasing temperature accelerating decoherence for all states. In contrast, common dephasing generates a markedly state dependent thermal response. Under common dephasing, the $\vert GHZ \rangle$ and $\vert Star\rangle$ states undergo complete coherence loss, the $\vert W\rangle$ state exhibits temperature independent stationary coherence, and the $\vert W\overline{W}\rangle$ state retains finite residual coherence at long times. Similar state dependent behaviour is also observed for mixed states. These results demonstrate that the thermal susceptibility of quantum coherence is governed jointly by the environmental configuration and the internal architecture of the multipartite quantum state. Furthermore, we establish a direct coherence temperature correspondence through representative thermometry tables, providing a \textit{proof-of-principle} foundation for coherence based quantum thermometry.