Harnessing coherence generation for precision single- and two-qubit quantum thermometry

TL;DR

This paper explores advanced quantum thermometry techniques using single- and two-qubit probes, demonstrating how ancilla-mediated coherence and qubit interactions enhance temperature measurement precision, especially at low temperatures.

Contribution

It introduces a novel approach employing ancilla-mediated coherence and qubit interactions to improve quantum thermometry accuracy, particularly at low temperatures.

Findings

Ancilla enhances thermometric sensitivity via coherence transfer.

Steady-state proximity improves measurement precision.

Adjusting qubit interactions enables high efficiency at low temperatures.

Abstract

Quantum probes, such as single- and two-qubit probes, can accurately measure the temperature of a bosonic bath. The current investigation assesses the precision of temperature estimate using quantum Fisher information and the accompanying quantum signal-to-noise ratio. Employing an ancilla as a mediator between the probe and the bath improves thermometric sensitivity by transmitting temperature information into the probe qubit's coherences. In addition, we analyze two interacting qubits that were initially entangled or separated as quantum probes for various environmental configurations. Our findings show that increased precision is gained when the probe approaches its steady state, which is determined by the coupling between the two qubits. Furthermore, we can obtain high efficiency temperature estimation for any low temperature by changing the interaction between the two qubits.