Generation of optical Schr\"odinger cat states in intense laser-matter interactions

TL;DR

This paper demonstrates that intense laser-atom interactions can generate non-classical light states, specifically optical Schrödinger cat states, through high-harmonic generation, revealing quantum features in high-intensity laser physics.

Contribution

It shows that high-harmonic generation in atoms can produce optical Schrödinger cat states, a novel quantum state generation method in intense laser-matter interactions.

Findings

Generation of optical Schrödinger cat states via high-harmonic generation.

Conditioned quantum states show superposition of initial and reduced amplitude coherent states.

Pathway for controlling non-classical states in high-intensity laser experiments.

Abstract

The physics of intense laser-matter interactions is described by treating the light pulses classically, anticipating no need to access optical measurements beyond the classical limit. However, the quantum nature of the electromagnetic fields is always present. Here, we demonstrate that intense laser-atom interactions may lead to the generation of highly non-classical light states. This was achieved by using the process of high-harmonic generation in atoms, in which the photons of a driving laser pulse of infrared frequency are up-converted into photons of higher frequencies in the extreme ultraviolet spectral range. The quantum state of the fundamental mode after the interaction, when conditioned on the high-harmonic generation, is a so-called Schr\"odinger cat state, which corresponds to a superposition of two distinct coherent states: the initial state of the laser and the coherent state reduced in amplitude that results from the interaction with atoms. The results open the path for investigations towards the control of the non-classical states, exploiting conditioning approaches on physical processes relevant to high-harmonic generation.