Leveraging collective effects for thermometry in waveguide quantum electrodynamics

TL;DR

This paper demonstrates a novel waveguide quantum electrodynamics technique that uses collective states of two transmon qubits to differentiate and measure local and global bath temperatures, advancing quantum thermometry.

Contribution

It introduces a new method leveraging collective states in waveguide QED for primary temperature sensing distinguishing local and global bath effects.

Findings

Successfully differentiates global and local bath temperatures

Uses transmission measurements to extract bath temperatures

Proposes a new quantum thermometry approach

Abstract

We report a proof-of-principle experiment for a new method of temperature measurements in waveguide quantum electrodynamics (wQED) experiments, allowing one to differentiate between global and local baths. The method takes advantage of collective states of two transmon qubits located in the center of a waveguide. The Hilbert space of such a system forms two separate subspaces (bright and dark) which are coupled differently to external noise sources. Measuring transmission through the waveguide allows one to extract separately the temperatures of the baths responsible for global and local excitations in the system. Such a system would allow for building a new type of primary temperature sensor capable of distinguishing between local and global baths.