Bosonic Diffusive Channel: Quantum Metrology via Finite Non-Gaussian Resource

TL;DR

This paper explores quantum metrology for dephasing in continuous-variable systems using non-Gaussian states, identifying optimal probes and practical measurement strategies for estimating decoherence rates.

Contribution

It introduces optimal non-Gaussian probe states and an ancilla-based measurement approach for efficient decoherence estimation in quantum systems.

Findings

Optimal probes include squeezed cat and symmetric squeezed compass states.

Numerical simulations confirm the effectiveness of the proposed methods.

Ancilla-based measurements enable decoherence estimation without direct cavity access.

Abstract

We investigate the estimation of dephasing-induced decoherence in continuous-variable quantum systems using non-Gaussian probe states. By purifying the open system, we identify optimal probes, specifically squeezed cat and symmetric squeezed compass states, via quantum Fisher information. These results are in agreement with numerical simulation. In settings where the intra-cavity field is inaccessible and standard measurements are impractical, utilizing an ancilla approach where a qubit traverses or interacts with the cavity field, leading to measurement of the qubit, hence allowing estimation of the dephasing rate via Wigner function reconstruction or less costly marginal distribution.