Gaussian interferometric power

Abstract

The interferometric power of a bipartite quantum state quantifies the precision, measured by quantum Fisher information, that such a state enables for the estimation of a parameter embedded in a unitary dynamics applied to one subsystem only, in the worst-case scenario where a full knowledge of the generator of the dynamics is not available a priori. For finite-dimensional systems, this quantity was proven to be a faithful measure of quantum correlations beyond entanglement. Here we extend the notion of interferometric power to the technologically relevant setting of optical interferometry with continuous-variable probes. By restricting to Gaussian local dynamics, we obtain a closed formula for the interferometric power of all two-mode Gaussian states. We identify separable and entangled Gaussian states which maximize the interferometric power at fixed mean photon number of the probes, and discuss the associated metrological scaling. At fixed entanglement of the probes, highly thermalized states can guarantee considerably larger precision than pure two-mode squeezed states.

6 pages, 3 figures. To appear in PRA

References in corpus (9)

• Entanglement in continuous variable systems: Recent advances and current perspectives
• Optimal Quantum Phase Estimation
• All non-classical correlations can be activated into distillable entanglement
• Quantum Metrology: Dynamics vs. Entanglement
• Phase estimation for thermal Gaussian states
• Entanglement quantification by local unitaries
• Quantifying nonclassicality: global impact of local unitary evolutions
• Verification of quantum discord
• Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

Cited by in corpus (7)

• Characterizing non-Markovianity via quantum interferometric power
• Multiple phase estimation for arbitrary pure states under white noise
• Quantum learning of coherent states
• Energy backflow in strongly coupled non-Markovian continuous-variables systems
• Device-independent quantum reading and noise-assisted quantum transmitters
• Estimation of nonclassical independent Gaussian processes by classical interferometry
• Non-Markovianity over ensemble averages in quantum complex networks