Quantum effect of inductance on geometric Cooper-pair transport

TL;DR

This paper models a flux-assisted Cooper-pair pump considering inductance effects, revealing subtle influences on charge transport and energy states, which are crucial for understanding quantum devices.

Contribution

It introduces a comprehensive model for the Cooper-pair sluice that includes inductance effects beyond the ideal phase bias, providing new insights into charge transport mechanisms.

Findings

Inductance has a weak but notable effect on charge transport.

External flux bias influences the inductance effect.

Energy level structures exhibit unusual features due to inductance.

Abstract

We introduce a model for a flux-assisted Cooper-pair pump, the sluice, which is used to study geometric charge transport. Our model allows for a nonvanishing loop inductance going beyond the usual treatment with an exact phase bias. We derive the device Hamiltonian and current operators for different elements of the system and calculate the pumped charge carried by the ground state in the adiabatic limit. We show that extending the model beyond the exact phase bias, has a weak but potentially non-negligible effect on the charge transport. This effect is observed to depend on the external flux bias. The adiabatic energy level and eigenstate structures are studied and the unusual features are explained. Finally, we discuss the requirements of adiabaticity.