CMSP COLLOQUIUM: What can we learn now from noisy quantum computers?
Channel: ICTP Condensed Matter and Statistical Physics
Date: 01/08/2023

Lev Ioffe studied theoretical physics at Landau Institute, Moscow obtaining his Ph.D. in 1985. An expert of condensed matter physics, in particular glasses and complex quantum systems, he held various professorships in the USA (Rutgers University, UW- Madison) and Europe (LPTHE, Paris). Among his many contributions, he is well known for influential research on Josephson junction arrays and superconducting systems as practical  implementations of quantum computation. He is presently a Senior Staff Researcher at Google AI Quantum.

Abstract:
At present quantum computers contain around 100 qubits whose life time is four orders of magnitude longer than the time for a gate operation. Can one do something useful with such a machine? I will argue that even these, very imperfect and noisy computers can address a number of physics questions that cannot be simulated by a classical computer in a realistic time. I will focus on problems of condensed matter and many-body physics. I will start with the short review of the physics of a superconducting quantum computing chip and outline the main physical effects that limit its coherence. I will then discuss the physics that is natural to simulate on such a device. One of the interesting questions is the formation of highly non-ergodic phases, which are still poorly understood. I will present our recent work in which we discovered the unexpected resilience of bound states in decorated spin chains, the first indication that quantum computer is on the verge of real scientific discoveries.