【时   间】26-June-2023（Monday）10:30 (Beijing time)

【地   点】量子院320会议室

【报告人】Anders W. Sandvik（Professor of Physics at Boston University, USA）

【主持人】Heng Fan（Institute of Physics, CAS and BAQIS）

【题   目】Quantum annealing of a programmable spin glasses

【摘   要】In quantum annealing, a system with two non-commuting interactions is slowly evolved from an initial trivial state to a final complex state. Ideally, if the evolution is fully adiabatic, the final state could be the ground state of a challenging classical Hamiltonian (e.g., encoding the solution of an optimization problem). Practical implementations of quantum annealing are limited by short coherence times, however, and there are also still fundamental questions about when (for what problems) substantial speedup (quantum advantage) can be achieved relative to classical computations. I will discuss recent experiments on a device with more than 5000 programmable superconducting qubits (the D-Wave Advantage system) with couplings programmed to one of the prototypical hard optimization problems - the 3D Ising spin glass ^[1]. While the coherence times are not long enough to reach the ground state, the results and comparisons with numerical simulations show that the system traverses the spin glass transition and the final state reached for different problem sizes and annealing times correctly reproduces expectations from scaling theory. The state of the art is now approaching the point where quantum annealing can address problems beyond the reach of classical computers.

[1] A. King et al., Nature 617, 61 (2023)

【报告人简介】Anders Sandvik is a Professor of Physics at Boston University. He completed his PhD at the University of California, Santa Barbara, in 1993, then carried out postdoctoral work at Florida State University and the University of Illinois at Urbana-Champaign before returning to his native country as a Senior Fellow of the Academy of Finland in 2000. He joined the faculty of Boston University in 2004. He has held several visiting appointments, including at the University of Tokyo (2008) and the Institute of Physics of the Chinese Academy of Sciences (2018-20). He is a Fellow of the American Physical society, a Simons Investigator in Physics, and the 2021 recipient of the Aneesur Rahman Prize for Computational Physics. His research focuses on computational studies in quantum many-body physics. He is the inventor of the Stochastic Series Expansion method and several other widely used simulation techniques. His detailed studies of lattice models have provided unique insights into collective quantum many-body states and their quantum phase transitions.