Ultra-sensitive phase estimation with white light

TL;DR

This paper demonstrates that quantum weak measurements enable ultra-sensitive detection of tiny phase shifts using white light, with a simplified scheme effective in the frequency domain regardless of time domain behavior.

Contribution

It introduces a simplified method for ultra-sensitive phase estimation with white light based on quantum weak measurements, extending previous schemes.

Findings

Amplification effect depends on spectrum size, not time domain behavior.

The scheme is simplified for experimental implementation.

Effective in detecting very small phase shifts with white light.

Abstract

An improvement of the scheme by Brunner and Simon [Phys. Rev. Lett. 105, 010405 (2010)] is proposed in order to show that quantum weak measurements can provide a method to detect ultrasmall longitudinal phase shifts, even with white light. By performing an analysis in the frequency domain, we find that the amplification effect will work as long as the spectrum is large enough, irrespective of the behavior in the time domain. As such, the previous scheme can be notably simplified for experimental implementations.