Event Details

Quantum Annealing: Myths and Realities

  • 2020-02-05
  • Prof. Anders Sandvik, Boston University, USA

Quantum annealing has been envisioned as a technique for effectively solving hard optimization problems, and devices already exist that claim to accomplish this by implementing an Ising model with programmable couplings (corresponding to an optimization problem) and transverse field (which introduces quantum fluctuations into the classical Ising spin configurations). It is still not clear, however, what degree of quantum speedup can be achieved for various problems of interest. Quantum annealers can also be used more broadly as laboratories for out-of-equilibrium quantum dynamics. Here I will discuss experiments carried out on a D-Wave annealing device programmed to emulate the standard 2D ferromagnetic Ising model on L*L lattices with L up to 32. By varying the annealing time and the lattice size, the interplay between ideal quantum annealing and noise from couplings to the environment of the qubits can be systematically investigated through the properties of the final classical state reached after the annealing process. I will discuss how such results can be analyzed with a phenomenological scaling ansatz, which can be applied also to numerical results for model systems [1].

Professor Anders Sandvik completed his M.Sc. at Abo Akademi University in Finland in 1989 and his Ph.D. at the University of California, Santa Barbara, in 1993. He carried out postdoctoral work at Florida State University, the University of Illinois at Urbana-Champaign, and Los Alamos National Laboratory, before returning to Finland as a Senior Fellow of the Academy of Finland in 2000. He has been at Boston University since 2004 and since 2018 he also holds an appointment at the Institute of Physics of the Chinese Academy of Sciences in Beijing. He has published 150 research articles on computational algorithms and their applications to condensed-matter systems at the electronic level. In recognition of his work on quantum magnetism, he was elected a Fellow of the American Physical Society in 2007. His recent research has been focused on quantum phase transitions beyond the standard paradigms.