Quasiperiodic circuit quantum electrodynamics

TL;DR

This paper introduces a superconducting circuit design that creates quasiperiodic nonlinear capacitive elements, enabling the simulation of topological and localization phenomena in quantum systems with potential applications in quantum simulation.

Contribution

It demonstrates a simple superconducting circuit setup that realizes quasiperiodic charge dynamics, allowing emulation of topological features and Anderson localization in quantum transport.

Findings

Protected Dirac points in transport degrees of freedom.

Suppression of classical finite-frequency current noise.

Charge localization evidenced by vanishing charge fluctuations.

Abstract

Superconducting circuits are an extremely versatile platform to realize quantum information hardware and to emulate topological materials. We here show how a simple arrangement of capacitors and conventional superconductor-insulator-superconductor junctions can realize an even broader class of systems, in the form of a nonlinear capacitive element which is quasiperiodic with respect to the quantized Cooper-pair charge. Our setup allows to create protected Dirac points defined in the transport degrees of freedom, whose presence leads to a suppression of the classical finite-frequency current noise. Furthermore, the quasiperiodicity can emulate Anderson localization in charge space, measurable via vanishing charge quantum fluctuations. The realization by means of the macroscopic transport degrees of freedom allows for a straightforward generalization to arbitrary dimensions and implements truly non-interacting versions of the considered models. As an outlook, we discuss potential ideas to simulate a transport version of the magic-angle effect known from twisted bilayer graphene.