Description:

Heterogeneities in the form of quenched disorder often have a fundamental impact on the emergent phases and phase transitions in quantum systems, with the quantum Ising model being a prominent example. Other interacting quantum models have been much less understood. In this talk, I will provide a brief overview of what we know about disorder effects close to the superfluid-insulator transition in low-dimensional arrays of Josephson junctions. Just like in other disordered quantum systems, renormalization group (RG) techniques turned out to be highly efficient in capturing the essence of the physics in these systems. Our ongoing work generalizes these RG results to three dimensions as well as to arbitrary circuits, capable of addressing various questions about their phases and phase transitions, in linear time of the number of Josephson junctions. A particularly interesting theoretical question is about the emergent bipartite and multipartite quantum entanglement between extended subsystems, aspects of which are highly non-trivial, yet universal in Ising-like models.

Istvan Kovacs, Assistant Professor, Northwestern University

Host: Venkat Chandrasekhar