Electromotive force in driven topological quantum circuits

TL;DR

This paper investigates how electromotive force affects the fractional Josephson effect in driven topological quantum circuits, providing insights into time-dependent control crucial for scalable quantum hardware.

Contribution

It introduces a new term in the quantum description that depends on circuit and magnetic field geometry, refining the understanding of time-dependent control in topological circuits.

Findings

A new term depending on circuit and magnetic field geometry is identified.

The emf's effect can be measured via current and charge in different geometries.

Results improve the theoretical framework for controlling topological quantum circuits.

Abstract

Time-dependent control of superconducting quantum circuits is a prerequisite for building scalable quantum hardware. The quantum description of these circuits is complicated due to the electromotive force (emf) induced by time-varying magnetic fields. Here, we examine how the emf modifies the fractional Josephson effect. We show that a time-varying flux introduces a new term that depends on the geometry of both the circuit and the applied magnetic field. This term can be probed via current and charge measurements in closed-loop and open-circuit geometries. Our results refine the current understanding of how to properly describe time-dependent control of topological quantum circuits.