Quantum enhanced optical phase estimation with a squeezed thermal state

Abstract

Quantum phase estimation protocols can provide a measuring method of phase shift with precision superior to standard quantum limit (SQL) due to the application of a nonclassical state of light. A squeezed vacuum state, whose variance in one quadrature is lower than the corresponding SQL, has been pointed out a sensitive resource for quantum phase estimation and the estimation accuracy is directly influenced by the properties of the squeezed state. Here we detailedly analyze the influence of the purity and squeezing level of the squeezed state on the accuracy of quantum phase estimation. The maximum precision that can be achieved for a squeezed thermal state is evaluated, and the experimental results are in agreement with the theoretical analyses. It is also found that the width of the phase estimation interval $\Delta \theta$ beyond SQL is correlated with the purity of the squeezed state.

7 pages, 5 figures

References in corpus (10)

• High-sensitivity diamond magnetometer with nanoscale resolution
• Entanglement-free Heisenberg-limited phase estimation
• Entanglement-enhanced measurement of a completely unknown phase
• Quantum Metrology: Dynamics vs. Entanglement
• Quantum-enhanced optical phase tracking
• Optimal phase measurements with pure Gaussian states
• Phase estimation for thermal Gaussian states
• Squeezed vacuum as a universal quantum probe
• Experimental generation of 8.4 dB entangled state with an optical cavity involving a wedged type-II nonlinear crystal
• Digital Quantum Estimation