Entangled laser beams and quantum ghost frequency comb

TL;DR

This paper investigates entangled laser beams, demonstrating a quantum ghost frequency comb with high-contrast correlations, and discusses its implications for nonlocal measurements and advanced quantum technologies.

Contribution

It introduces the concept of quantum ghost frequency comb (QGFC) generated by entangled laser beams and explores its nonlocal coherent behavior in continuous wave operation.

Findings

Entangled laser beams produce comb-like correlations with 100% contrast.

Quantum ghost frequency comb enables high-resolution, long-distance nonlocal measurements.

Bright QGFCs outperform entangled photon pairs in precision spectroscopy and timing.

Abstract

This letter reports on the study of entangled laser beams, or entangled coherent states, from their generation to their nonlocal coherent behavior. Although in continuous wave operation, the entangled laser beams are able to produce comb-like correlation with 100\% contrast in distant joint photodetection. We name this comb-function quantum ghost frequency comb (QGFC). What is the cause of these periodic sharp correlations? Can we trust zero-coincidences, or anti-correlation, in the joint measurement of CW laser beams? Besides its fundamental interests, bright QGFCs make important contributions to the fields of nonlocal precision spectroscopy, positioning, and time transfer. Superior to entangled photon pairs, measurements of entangled laser beams do not rely on photon counting and can be performed over greater distance in shorter time with higher resolution and accuracy.