Ultraprecise time-difference measurement via enhanced dual pointers with multiple weak interactions

TL;DR

This paper introduces an enhanced dual-pointer weak value amplification scheme with multiple weak interactions, achieving ultraprecise time-difference measurements and revealing quantum effects through violation of Leggett-Garg inequality.

Contribution

It develops a novel triple weak interaction scheme with variable spectrum sources, significantly improving measurement precision and demonstrating quantum effects in weak-value amplification.

Findings

Achieved a time-difference precision of 3.34×10^{-5} with a 6 nm spectral width.

Measured a weak value of 1478 with two-order WVA enhancement.

Demonstrated violation of Leggett-Garg inequality indicating quantum effects.

Abstract

Standard weak measurement with an assistant pointer and single weak interaction constrains measurement precision and quantity of interaction parameters, and a compelling characterization of quantum effect featuring weak-value amplification (WVA) remains elusive. Here, we theoretically and experimentally demonstrate an enhanced dual-pointer WVA scheme based on multiple weak interactions and variable spectrum sources. Developing triple weak interactions, momentum P pointer reaches an optimal time-difference precision of $3.34 \times {10^{-5}}$ as at 6 nm spectral width, and intensity I pointer achieves a displacement resolution of 148.8 fm within 400 kHz linewidth. A quantum effect associated with an anomalous weak value is revealed by an observable violation of a Leggett-Garg inequality. The I-pointer weak value is measured to be 1478 using multiple weak interactions and high signal-to-noise detection, achieving a two-order-of-magnitude WVA enhancement compared to standard weak measurement. Our work opens up a practical avenue for minuscule quantumness measurements in challenging environments.