Achieving the ultimate quantum timing resolution

TL;DR

This paper introduces a quantum measurement scheme that significantly enhances timing resolution, enabling detection of ultrashort pulse separations and intensity differences far beyond traditional methods.

Contribution

The authors develop and experimentally demonstrate a temporal-mode demultiplexing technique achieving quantum-limited precision in time-delay measurements.

Findings

Resolved temporal separations ten times smaller than pulse duration

Detected intensity differences up to a factor of 100

Surpassed standard intensity detection methods by over an order of magnitude

Abstract

Accurate time-delay measurement is at the core of many modern technologies. Here, we present a temporal-mode demultiplexing scheme that achieves the ultimate quantum precision for the simultaneous estimation of the temporal centroid, the time offset, and the relative intensities of an incoherent mixture of ultrashort pulses at the single-photon level. We experimentally resolve temporal separations ten times smaller than the pulse duration, as well as imbalanced intensities differing by a factor of $10^{2}$. This represents an improvement of more than an order of magnitude over the best standard methods based on intensity detection.