Attosecond-Resolution Hong-Ou-Mandel Interferometry

TL;DR

This paper advances Hong-Ou-Mandel interferometry to achieve attosecond resolution in a dual-arm setup, enabling ultra-precise measurements at nanometer scales relevant to biology and materials science.

Contribution

It introduces a method to reach the fundamental resolution limits of HOM interferometry in a dual-arm configuration, surpassing previous femtosecond-scale limitations.

Findings

Achieved few-attosecond (nanometer) resolution in HOM interferometry.

Demonstrated potential for applications in cell biology and 2D materials.

Enhanced measurement precision using statistical estimation theory.

Abstract

When two indistinguishable photons are each incident on separate input ports of a beamsplitter they `bunch' deterministically, exiting via the same port as a direct consequence of their bosonic nature. This two-photon interference effect has long-held the potential for application in precision measurement of time delays, such as those induced by transparent specimens with unknown thickness profiles. However, the technique has never achieved resolutions significantly better than the few femtosecond (micron)-scale other than in a common-path geometry that severely limits applications. Here we develop the precision of HOM interferometry towards the ultimate limits dictated by statistical estimation theory, achieving few-attosecond (or nanometre path length) scale resolutions in a dual-arm geometry, thus providing access to length scales pertinent to cell biology and mono-atomic layer 2D materials.