Sub-Poissonian Statistics and Quantum Non-Gaussianity from High-Harmonic Generation

TL;DR

This paper demonstrates that high-harmonic generation in semiconductors produces non-classical, entangled, and quantum non-Gaussian light states, establishing it as a promising platform for quantum information applications.

Contribution

It introduces the generation and certification of non-classical, entangled, and quantum non-Gaussian states via high-harmonic generation, supported by experimental and modeling approaches.

Findings

Higher-order harmonics are squeezed and entangled.

Generated states exhibit sub-Poissonian photon statistics.

Quantum non-Gaussian states are produced, useful for quantum information.

Abstract

Quantum technologies are powered by platforms to generate complex non-classical states of matter or light to realize applications. We investigate the non-classical properties of high-harmonic generation in semiconductors, an emerging photonic platform. Measuring the click statistics of three double-digit orders, we evaluate witness operators to certify the non-classicality of the generated states. We show that higher-order harmonics driven by a coherent laser are squeezed and entangled. The properties of the emission are well retrieved with an entangled Gaussian state model, obtained by numerical state optimization to multiple observables. Additionally, we perform inter-order heralded measurements to engineer the quantum state of the emission. The heralded states have distinct properties, showing sub-Poissonian photon statistics. Further, we witness the generation of a quantum non-Gaussian state, a resource highly relevant for quantum information. With this, we establish high-harmonic generation as a platform for generating quantum optical resources.