Ryosuke Imai

Ryosuke Imai
QunaSys Inc.

Doctor of Science

About

9
Publications
442
Reads
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102
Citations
Additional affiliations
April 2016 - March 2019
Waseda University
Position
  • Research Assistant

Publications

Publications (9)
Preprint
Measuring expectation values of observables is an essential ingredient in variational quantum algorithms. A practical obstacle is the necessity of a large number of measurements for statistical convergence to meet requirements of precision, such as chemical accuracy in the application to quantum chemistry computations. Here we propose an algorithm...
Article
Full-text available
To explore the possibilities of a near-term intermediate-scale quantum algorithm and long-term fault-tolerant quantum computing, a fast and versatile quantum circuit simulator is needed. Here, we introduce Qulacs, a fast simulator for quantum circuits intended for research purpose. We show the main concepts of Qulacs, explain how to use its feature...
Conference Paper
A theoretical study of excitonic condensation in a driven-dissipative semiconductor is presented. The system that we analyze is driven by a coherent light that creates electron-hole pairs and also includes the process of the annihilation of the pairs. To study the steady state realized in this nonequilibrium system, we employ the Schwinger-Keldysh...
Preprint
We introduce Qulacs, a fast simulator for quantum circuits intended for research purpose. To explore the possibilities of a near-term intermediate-scale quantum algorithm and long-term fault-tolerant quantum computing, a fast and versatile quantum circuit simulator is needed. Herein we show the main concepts of Qulacs, explain how to use its featur...
Article
We investigate how the presence of a localized impurity in a Bose-Einstein condensate of trapped cold atoms that interact with each other weakly and repulsively affects the profile of the condensed and excited components at zero temperature. By solving the Gross-Pitaevskii and Bogoliubov–de Gennes equations, we find that an impurity-boson contact a...
Preprint
We investigate how the presence of a localized impurity in a Bose-Einstein condensate of trapped cold atoms that interact with each other weakly and repulsively affects the profile of the condensed and excited components at zero temperature. By solving the Gross-Pitaevskii and Bogoliubov-de Gennes equations, we find that an impurity-boson contact a...
Article
We investigate the dynamical properties of the finite-size Dicke model coupled to a photon reservoir in the dispersive regime. The system–reservoir coupling in our Hamiltonian includes counter-rotating terms, which are relevant in the strong atom–cavity coupling. Because the dispersive regime is considered, the dynamics of low-energy states are des...
Article
We investigate the finite-size Dicke model with photon leakage. It is shown that the symmetry breaking states, which correspond to the ground states in the superradiant phase in the thermodynamic limit, are stable, while the eigenstates of the isolated finite-size Dicke Hamiltonian conserve parity symmetry and are non-superradiant states. We introd...
Preprint
We investigate the dynamical properties of the finite-size Dicke model coupled to a photon reservoir in the dispersive regime. The system-reservoir coupling in our Hamiltonian includes counter-rotating terms, which are relevant in the strong atom-cavity coupling. Because the dispersive regime is considered, the dynamics of low-energy states are des...

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Project (1)