Quantum improved measurement of time transfer

TL;DR

This paper demonstrates an experimental quantum-enhanced method for time transfer measurement that surpasses the standard quantum limit, achieving unprecedented precision in timing over large distances.

Contribution

It introduces the first experimental demonstration of quantum-enhanced time transfer measurement surpassing the SQL using multimode squeezing frequency combs.

Findings

Timing fluctuation reduced from 8.9E-23s to 7.5E-23s

Achieved measurement precision beyond the standard quantum limit

Utilized multimode squeezing frequency comb with 1.5 dB phase quadrature noise reduction

Abstract

Accurate time transfer has become a crucial issue for future space experiments which require increasing resolution over large distances. In 2008, a scheme combining homodyne detection and mode-locked femtosecond lasers was proposed that leads to a potential timing precision reaching the yoctosecond range; with a multimode quantum frequency comb as the input field, the sub-shot noise measurement for the time transfer can further improve the timing precision. Based on this scheme and applying the multimode squeezing frequency comb that was measured to have a phase quadrature quantum noise reduction of 1.5 dB at the analyzing frequency 2MHz, the measurable timing fluctuation was reduced from a shot-noise limited value of 8.9E-23s to 7.5E-23s. To our knowledge, this is the first experimental demonstration of the time transfer measurement that achieves a precision beyond the standard quantum limit (SQL).