Generation of optical Schrodinger cat states by generalized photon subtraction

We propose a high-rate generation method of optical Schrodinger 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 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 (vertical bar alpha vertical bar >= 2) can exceed megacounts per second, about 103 to 106 times better than typical rates of conventional photon subtraction. This rate would be improved further by the progress of related technologies. The ability to generate non-Gaussian states at a high rate is important in quantum computing using optical continuous variables, where scalability has been demonstrated but preparation of non-Gaussian states of light remains as a challenging task for universality and fault tolerance. Our proposal reduces the difficulty of the state preparation and opens a way for practical applications in quantum optics.

Automated summary

We propose a high-rate generation method of optical Schrodinger cat states by photon number measurement in one mode of two-mode Gaussian states, which relaxes constraints on experimental parameters and allows for a high generation rate. This method can potentially exceed conventional photon subtraction rates by about 103 to 106 times, making it important for quantum computing applications.