Achieving the Ultimate Quantum Timing Resolution

Vahid Ansari,John M Donohue,Jano Gil-Lopez,Zdeněk Hradil,Jaroslav Řeháček,Christine Silberhorn,Benjamin Brecht,Luis L Sánchez-Soto

doi:10.1103/prxquantum.2.010301

Abstract

Accurate time-delay measurement is at the core of many modern technologies. 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 10 times smaller than the pulse duration, as well as imbalanced intensities differing by a factor of 102. This represents an improvement of more than an order of magnitude over the best standard methods based on intensity detection.Received 3 September 2020Accepted 12 November 2020DOI:https://doi.org/10.1103/PRXQuantum.2.010301Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNonlinear opticsPhotonicsQuantum metrologyQuantum opticsQuantum parameter estimationAtomic, Molecular & OpticalQuantum Information

Highlights

The measurement of the time delay between two clocks is of paramount importance for many applications, from navigation and global positioning [1] to tests of general relativity [2], long baseline interferometry [3], optical coherence tomography [4], and gravitational wave detection [5], to cite but a few
The directdetection Cramér-Rao lower bound (CRLB) is calculated for an imaging system with the same quantum efficiency as our apparatus, detecting exactly the same number of photons
The blue circles are mean values of the estimates retrieved from repeated measurements with the constrained generalized least squares (GLS) estimation

Summary

Introduction

The measurement of the time delay between two clocks is of paramount importance for many applications, from navigation and global positioning [1] to tests of general relativity [2], long baseline interferometry [3], optical coherence tomography [4], and gravitational wave detection [5], to cite but a few. Distance information can be extracted from timing information using the time-of-flight principle [7], which detects reflections off of distant objects. In these cases and others, the main goal of a timing measurement is to estimate specific properties of a received signal consisting of multiple pulses, such as relative time delays, centroids, and relative intensities, and not necessarily full temporal profile reconstruction. The optical pulses being measured share little or no coherence

Objectives

Methods

Results