Shuhei Tamate

TL;DR: In this article, a scalable optical processor with electronic feedback that can be realized at large scale with room-temperature technology is presented. But it is not suitable for large-scale combinatorial optimizations.

TL;DR: A scalable optical processor with electronic feedback that can be realized at large scale with room-temperature technology is presented and is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems.

TL;DR: In this article, an interferometer for particles with internal degrees of freedom is introduced to investigate the mechanism of weak measurement by using an inter-ferometric framework, and it is revealed that the extraordinary displacement of the probe wavepackets in weak measurement is due to the Pancharatnam phase associated with post-selection.

TL;DR: In this article, a 16-bit coherent Ising machine based on a network of time-division-multiplexed femtosecond degenerate optical parametric oscillators is presented.

Abstract: The one-clean-qubit model (or the deterministic quantum computation with one quantum bit model) is a restricted model of quantum computing where all but a single input qubits are maximally mixed. It is known that the probability distribution of measurement results on three output qubits of the one-clean-qubit model cannot be classically efficiently sampled within a constant multiplicative error unless the polynomial-time hierarchy collapses to the third level [T. Morimae, K. Fujii, and J. F. Fitzsimons, Phys. Rev. Lett. 112, 130502 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.130502]. It was open whether we can keep the no-go result while reducing the number of output qubits from three to one. Here, we solve the open problem affirmatively. We also show that the third-level collapse of the polynomial-time hierarchy can be strengthened to the second-level one. The strengthening of the collapse level from the third to the second also holds for other subuniversal models such as the instantaneous quantum polynomial model [M. Bremner, R. Jozsa, and D. J. Shepherd, Proc. R. Soc. A 467, 459 (2011)PRLAAZ1364-502110.1098/rspa.2010.0301] and the boson sampling model [S. Aaronson and A. Arkhipov, STOC 2011, p. 333]. We additionally study the classical simulatability of the one-clean-qubit model with further restrictions on the circuit depth or the gate types.