Long-range entanglement and quantum correlations in a multi-frequency comb system

TL;DR

This paper theoretically demonstrates a mechanism to generate multiple entangled frequency combs across a broad spectral range, enabling advanced quantum sensing and information processing applications.

Contribution

It introduces a novel method for producing multi-frequency comb entanglement via cascaded nonlinear processes mediated by a single idler comb.

Findings

Generation of inter- and intracomb two-mode squeezing and entanglement across ultraviolet to mid-IR.

Ability to engineer on-demand multimode quantum light through covariance matrix optimization.

Potential applications in broadband ghost spectroscopy and squeezing-enhanced measurements.

Abstract

Frequency combs are multimode photonic systems that underlie countless precision sensing and metrology applications. Since their invention over two decades ago, numerous efforts have pushed frequency combs to broader bandwidths and more stable operation. More recently, quantum squeezing and entanglement have been explored in single frequency comb systems for quantum advantages in sensing and signal multiplexing. However, the production of quantum light across multiple frequency combs remains unexplored. In this work, we theoretically explore a mechanism that generates a series of nonlinearly coupled frequency combs through cascaded three-wave upconversion and downconversion processes mediated by a single idler comb. We show how this system generates inter- and intracomb two-mode squeezing and entanglement spanning a very large spectral range, from ultraviolet to mid-IR frequencies. Finally, we show how this system can be engineered to produce on-demand multimode quantum light through covariance matrix optimization. Our findings could enable tunable broadband ghost spectroscopy protocols, squeezing-enhanced pump-probe measurements, and broadband entanglement between spectrally-multiplexed quanta of information.