Towards Schrödinger Cat States in the Second Harmonic Generation

Fuente: arXiv
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Autores principales: Singh, Ranjit, Barinov, Leonid A., Amosov, Grigori G., Masalov, Anatoly V.
Formato: Preprint
Publicado: 2026
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author Singh, Ranjit
Barinov, Leonid A.
Amosov, Grigori G.
Masalov, Anatoly V.
author_facet Singh, Ranjit
Barinov, Leonid A.
Amosov, Grigori G.
Masalov, Anatoly V.
contents We investigate the quantum evolution of the pump field in second-harmonic generation under strong pump depletion. Starting from a coherent state, the pump develops a nonclassical phase-space structure resembling a Schrödinger cat state. This behavior originates from phase instability induced by vacuum fluctuations of the harmonic mode. A rigorous quantum analysis has been performed for mean photon numbers up to $\langle \hat n \rangle = 100$ in pump mode. For larger photon numbers, up to $\langle \hat n \rangle = 10^{7}$, the dynamics have been analyzed using a classical trajectory method with sampled initial conditions that reproduces the main features of the quantum evolution. The results indicate that nonlinear frequency conversion can generate macroscopic superposition-like states of the pump field. Although the resulting state is not pure due to correlations with the second-harmonic wave, it remains non-classical with negative zones of Wigner function. These results indicate that strongly nonlinear frequency conversion can provide a scalable route toward macroscopic nonclassical states of light.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24067
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Towards Schrödinger Cat States in the Second Harmonic Generation
Singh, Ranjit
Barinov, Leonid A.
Amosov, Grigori G.
Masalov, Anatoly V.
Quantum Physics
Optics
We investigate the quantum evolution of the pump field in second-harmonic generation under strong pump depletion. Starting from a coherent state, the pump develops a nonclassical phase-space structure resembling a Schrödinger cat state. This behavior originates from phase instability induced by vacuum fluctuations of the harmonic mode. A rigorous quantum analysis has been performed for mean photon numbers up to $\langle \hat n \rangle = 100$ in pump mode. For larger photon numbers, up to $\langle \hat n \rangle = 10^{7}$, the dynamics have been analyzed using a classical trajectory method with sampled initial conditions that reproduces the main features of the quantum evolution. The results indicate that nonlinear frequency conversion can generate macroscopic superposition-like states of the pump field. Although the resulting state is not pure due to correlations with the second-harmonic wave, it remains non-classical with negative zones of Wigner function. These results indicate that strongly nonlinear frequency conversion can provide a scalable route toward macroscopic nonclassical states of light.
title Towards Schrödinger Cat States in the Second Harmonic Generation
topic Quantum Physics
Optics
url https://arxiv.org/abs/2603.24067