Generation of optical Schr\"{o}dinger's cat states by generalized photon subtraction

TL;DR

This paper introduces a generalized photon subtraction method for generating optical Schr"{o}dinger's cat states at rates vastly exceeding traditional techniques, facilitating practical quantum computing applications.

Contribution

It proposes a new approach based on photon number measurement in two-mode Gaussian states, relaxing experimental constraints and enabling high-rate, large-amplitude cat state generation.

Findings

Generation rate exceeds 10^3 to 10^6 times traditional methods.

Method achieves high-fidelity, large-amplitude cat states.

Potential for scalable quantum computing with non-Gaussian states.

Abstract

We propose a high-rate generation method of optical Schr\"{o}dinger's cat states. Thus far, photon subtraction from squeezed vacuum states has been a standard method in cat-state generation, but its constraints on experimental parameters limit the generation rate. In this paper, we consider the state generation by photon number measurement in one mode of arbitrary two-mode Gaussian states, which is a generalization of conventional photon subtraction, and derive the conditions to generate high-fidelity and large-amplitude cat states. Our method relaxes the constraints on experimental parameters, allowing us to optimize them and attain a high generation rate. Supposing realistic experimental conditions, the generation rate of cat states with large amplitudes ($|\alpha| \ge 2)$ can exceed megacounts per second, about $10^3$ to $10^6$ times better than typical rates of conventional photon subtraction. This rate would be improved further by the progress of related technologies. Ability to generate non-Gaussian states at a high rate is important in quantum computing using optical continuous variables, where scalable computing platforms have been demonstrated but preparation of non-Gaussian states of light remains as a challenging task. Our proposal reduces the difficulty of the state preparation and open a way for practical applications in quantum optics.