Anomalous Amplification of a Homodyne signal via Almost-Balanced Weak Values

TL;DR

This paper demonstrates the almost-balanced weak values amplification (ABWV) technique using a modified Sagnac interferometer, achieving significantly higher amplification factors than traditional weak-value methods, especially with spatially separated counter-propagating beams.

Contribution

The paper introduces and experimentally validates a modified ABWV technique with spatially separated beams, achieving unprecedented amplification factors in a Sagnac interferometer.

Findings

Achieved amplification factors up to 1.2×10^7.

Amplification increases monotonically with decreasing post-selection phase in ABWV.

ABWV outperforms traditional weak-value amplification in this setup.

Abstract

The technique of almost-balanced weak values amplification (ABWV) was recently proposed [Phys. Rev. Lett. 116: 100803 (2016)]. We demonstrate this technique using a modified Sagnac interferometer, where the counter-propagating beams are spatially separated. The separation between the two beams provides additional amplification, with respect to using colinear beams in a Sagnac interferometer. As a demonstration of the technique, we perform measurements of the angular velocity in one of the mirrors of the interferometer. Within the same setup, the weak-value amplification technique is also performed for comparison. Much higher amplification factors can be obtained using the almost-balanced weak values technique, with the best one achieved in our experiments being as high as $1.2\times10^7$. In addition, the amplification factor monotonically increases with decreasing post-selection phase for the ABWV case in our experiments, which is not the case for weak-value amplification at small post-selection phases.