日時：2018年 9月7日（金） 10:00-12:00,13:00-15:00
講師：Prof. (Emeritus) Yoshihisa Yamamoto
所属：Department of Applied Physics, Stanford University ImPACT Program Manager, Japan Science and Technology Agency
題目：Physics of quantum-to-classical crossover and coherent Ising machines;
The quantum computational model based on unitary rotation of state vectors in a closed system was proposed in mid-1980s. Feasibility of developing a practical computer based on this concept is still elusive in spite of world-wide research efforts over the past thirty years. In the beginning of the 21 century, a new concept of dissipative quantum computation utilizing quantum-to-classical crossover in an open-dissipative system emerged as an alternative approach to practical quantum computers. In this lecture, we will review the basic concept, theoretical methods and state of the art in experimental implementation of a particular machine, called coherent Ising machine, along this new direction.
Day 1 topics: Gate-based quantum computation vs. network-based quantum computation, optical delay line coupling CIM vs. measurement feedback coupling CIM, squeezing and spontaneous symmetry breaking in optical parametric oscillators, natural phase error correction, state reduction induced by approximate homodyne measurements, quantum parallel search assisted by non-Gaussian wave-packets, benchmark against modern digital computers, QNN cloud system.
Day 2 topics: Quantum theory of CIM, measurement-feedback master equation, positive P representation vs. truncated Wigner representation of density operators, c-number stochastic differential equations, replicator dynamics, Gaussian approximation, standard quantum limit and beyond in CIM, einselection and coherent states as unique pointer basis, quantum Darwinism and quantum-to-classical crossover in non-equilibrium systems.
紹介教員：永長 直人 教授、樽茶 清悟 教授