# Hysteretic superconducting heat-flux quantum modulator

## TL;DR

This paper investigates a hysteretic superconducting heat-flux quantum modulator based on a SQUID, demonstrating its potential as a high-frequency superconducting memory element through thermal current and temperature hysteresis.

## Contribution

It introduces a novel heat-flux modulator utilizing hysteresis in a thermally-biased SQUID with finite inductance, enabling temperature-based memory applications.

## Key findings

- Thermal current exhibits hysteretic modulation with external magnetic flux.
- Temperature shows sharp hysteretic jumps up to ~38mK.
- Device can operate at GHz frequencies for superconducting memory.

## Abstract

We discuss heat transport in a thermally-biased SQUID in the presence of an external magnetic flux, when a non-negligible inductance of the SQUID ring is taken into account. A properly sweeping driving flux causes the thermal current to modulate and behave hysteretically. The response of this device is analysed as a function of both the hysteresis parameter and degree of asymmetry of the SQUID, highlighting the parameter range over which hysteretic behavior is observable. Markedly, also the temperature of the SQUID shows hysteretic evolution, with sharp transitions characterized by temperature jumps up to, e.g., ~ 38mK for a realistic Al-based setup. In view of these results, the proposed device can effectively find application as a temperature-based superconducting memory element, working even at GHz frequencies by suitably choosing the superconductor on which the device is based.