Discrimination of Ohmic thermal baths by quantum dephasing probes

TL;DR

This paper investigates how dephasing quantum probes can distinguish structured thermal baths at different temperatures, highlighting the effectiveness of qutrits over qubits and the limited advantage of multi-qubit registers.

Contribution

It provides an exact analysis of the dynamics and error probabilities for different quantum probes in thermal bath discrimination, revealing the optimal probe types and interaction times.

Findings

Qutrit probes outperform qubits in temperature discrimination.

Dephasing probes are effective at low temperatures.

Two-qubit registers do not outperform separate qubits.

Abstract

We address the discrimination of structured baths at different temperatures by dephasing quantum probes. We derive the exact reduced dynamics and evaluate the minimum error probability achievable by three different kinds of quantum probes, namely a qubit, a qutrit and a quantum register made of two qubits. Our results indicate that dephasing quantum probes are useful in discriminating low values of temperature, and that lower probabilities of error are achieved for intermediate values of the interaction time. A qutrit probe outperforms a qubit one in the discrimination task, whereas a register made of two qubits does not offer any advantage compared to two single qubits used sequentially.