Enhanced weak-value amplification via photon recycling

TL;DR

This paper demonstrates a photon recycling technique in weak-value amplification that nearly doubles the signal-to-noise ratio, surpassing traditional methods and enabling more sensitive measurements of mirror tilt.

Contribution

The authors experimentally implement recycled weak-value measurements with photon recycling, achieving significant signal and SNR improvements over standard weak-value and direct measurement methods.

Findings

Signal improvement factor of 4.4 ± 0.2

SNR improvement of 2.10 ± 0.06

Potential SNR enhancement up to 6 with lower losses

Abstract

In a quantum-noise limited system, weak-value amplification using post-selection normally does not produce more sensitive measurements than standard methods for ideal detectors: the increased weak value is compensated by the reduced power due to the small post-selection probability. Here we experimentally demonstrate recycled weak-value measurements using a pulsed light source and optical switch to enable nearly deterministic weak-value amplification of a mirror tilt. Using photon counting detectors, we demonstrate a signal improvement by a factor of $4.4 \pm 0.2$ and a signal-to-noise ratio improvement of $2.10 \pm 0.06$, compared to a single-pass weak-value experiment, and also compared to a conventional direct measurement of the tilt. The signal-to-noise ratio improvement could reach around 6 for the parameters of this experiment, assuming lower loss elements.