Quantum computing from a disordered-systems perspective (Groupe de travail Quantique)
Chris Baldwin
University of Maryland
Tue, Apr. 04th 2023, 11:00-12:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
Quenched disorder, in the sense of random imperfections in a system, is
both a blessing and a curse for scientists — it can give rise to a host
of novel phenomena, but it also tends to impede transport and
communication. Here we cover examples of both from our work on quantum
dynamics, motivated primarily by proposals for quantum computing and
quantum information protocols.
In the first part, we discuss tunneling processes in “rugged energy
landscapes”, of which the classic optimization problems from computer
science (such as Traveling Salesman and Satisfiability) are examples.
After describing how many such problems share essential features with
mean-field spin glasses — long-range interactions, disorder, frustration
— we summarize our understanding of the quantum dynamical phases in the
latter.
In the second part, we consider the opposite extreme of 1D
nearest-neighbor spin chains. We describe how “Lieb-Robinson bounds”
have proven to be an invaluable tool for studying both many-body
dynamics and constraints on quantum information protocols. We then cover
our recent work developing Lieb-Robinson bounds tailored to disordered
spin chains.