3-junction SQUID rocking ratchet

TL;DR

This paper demonstrates that 3-junction SQUIDs can function as efficient rocking ratchets, producing quantized voltage rectification under ac drive, with experimental results matching numerical simulations including thermal effects.

Contribution

It introduces the use of 3-junction SQUIDs as rocking ratchets and explores their behavior under various drive frequencies, including quantized voltage rectification.

Findings

Voltage rectification observed in 3-junction SQUIDs under ac bias.

Quantized rectified voltage at high-frequency drives.

Experimental results agree with numerical simulations including thermal noise.

Abstract

We investigate 3-junction SQUIDs which show voltage rectification if biased with an ac current drive with zero mean value. The Josephson phase across the SQUID experiences an effective ratchet potential, and the device acts as an efficient rocking ratchet, as demonstrated experimentally for adiabatic and nonadiabatic drive frequencies. For high-frequency drives the rectified voltage is quantized due to synchronization of the phase dynamics with the external drive. The experimental data are in excellent agreement with numerical simulations including thermal fluctuations.