Towards the observation of phase locked Bloch oscillations in arrays of small Josephson junctions

TL;DR

This paper proposes an experimental setup and simulations to observe phase-locked Bloch oscillations in small Josephson junction arrays, emphasizing the importance of high-impedance environments and drive conditions.

Contribution

It introduces a realistic circuit design and identifies key parameters for observing phase-locked Bloch oscillations in Josephson junction arrays.

Findings

High-impedance environment is essential for phase locking.

Drive shape and electron temperature affect step width and shape.

Preliminary measurements support simulation predictions.

Abstract

We have designed an experiment and performed extensive simulations and preliminary measurements to identify a set of realistic circuit parameters that should allow the observation of constant-current steps at I=2ef in short arrays of small Josephson junctions under external AC drive of frequency f. Observation of these steps demonstrating phase lock of the Bloch oscillations with the external drive requires a high-impedance environment for the array, which is provided by on-chip resistors close to the junctions. We show that the width and shape of the steps crucially depend on the shape of the drive and the electron temperature in the resistors.