Ab-initio Quantum Enhanced Optical Phase Estimation Using Real-time Feedback Control

TL;DR

This paper demonstrates a quantum-enhanced optical phase estimation method that uses real-time feedback and squeezed states to achieve precision beyond the shot noise limit, enabling advances in quantum measurement technologies.

Contribution

It introduces a fully deterministic, ab-initio phase estimation protocol combining real-time Bayesian feedback with squeezed states, surpassing classical measurement limits.

Findings

Achieved phase estimation beyond shot noise limit

Implemented real-time Bayesian feedback control

Demonstrated robustness with squeezed states

Abstract

Optical phase estimation is a vital measurement primitive that is used to perform accurate measurements of various physical quantities like length, velocity and displacements. The precision of such measurements can be largely enhanced by the use of entangled or squeezed states of light as demonstrated in a variety of different optical systems. Most of these accounts however deal with the measurement of a very small shift of an already known phase, which is in stark contrast to ab-initio phase estimation where the initial phase is unknown. Here we report on the realization of a quantum enhanced and fully deterministic phase estimation protocol based on real-time feedback control. Using robust squeezed states of light combined with a real-time Bayesian estimation feedback algorithm, we demonstrate deterministic phase estimation with a precision beyond the quantum shot noise limit. The demonstrated protocol opens up new opportunities for quantum microscopy, quantum metrology and quantum information processing.