# Atsushi Yamamura's research while affiliated with The University of Tokyo and other places

## Publications (8)

Preprint
We study the emergence of non-Gaussian quantum features in pulsed squeezed light generation with a mesoscopic number (i.e., dozens to hundreds) of pump photons. Due to the strong optical nonlinearities necessarily involved in this regime, squeezing occurs alongside significant pump depletion, compromising the predictions made by conventional semicl...
Preprint
The quantum features of ultrashort-pulse optical parametric oscillators (OPOs) are theoretically investigated in the nonlinear regime near and above threshold. Starting from basic premises of input-output theory, we derive a general quantum model for pulsed OPOs subject to $\chi^{(2)}$ interactions between a multimode signal cavity and a non-resona...
Article
The quantum features of ultrashort-pulse optical parametric oscillators (OPOs) are theoretically investigated in the nonlinear regime near and above threshold. Starting from basic premises of input-output theory, we derive a general quantum model for pulsed OPOs subject to χ(2) interactions between a multimode signal cavity and a non-resonant broad...
Article
The coherent Ising machine (CIM) is a degenerate optical parametric oscillator (DOPO) network for solving Ising combinatorial optimization problems. We formulate a theoretical model for the CIM with discrete-time measurement feedback processes, and perform numerical simulations for the simplest network, composed of two degenerate optical parametric...

## Citations

... The clearest indication of this effective classicality is that similar performance to demonstrated CIMs may be achieved by simulating the mean-field dynamics 119,180,181,214 . However, with sufficiently high nonlinearity to loss in their constituent DOPOs, CIMs can be firmly in the quantum regime 215 and have a strong connection with quantum annealers 127 . Exploring how to construct experimental CIMs in which quantum effects play a crucial role, and designing them so that quantum effects improve the performance of the machine, are two topics of active investigation 120 . ...
... On the other hand, there is a microscopic model, called the Gaussian approximation model, that provides a better approximation of the measurement process [74]. Moreover, we should mention that more general quantum models of the MFB-CIM without the Gaussian approximation have been derived for both discrete time models [75] and continuous time models [76]. In future work, we will need to use these more general quantum models to evaluate the performance of CIM-L0-RBCS. ...