Ultra-low carrier density superconducting bolometers with single photon sensitivity based on magic-angle twisted bilayer graphene

TL;DR

This paper demonstrates that magic-angle twisted bilayer graphene superconductors can detect single infrared photons due to their ultra-low carrier density, enabling highly sensitive quantum sensors and bolometers.

Contribution

It reveals the photon-induced destruction of superconductivity in MATBG and explores its potential for single photon detection and quantum sensing applications.

Findings

Single infrared photon absorption destroys superconductivity in MATBG.

Device can function as a single photon detector with Poissonian click statistics.

Ultra-low carrier density leads to record-breaking sensitivity for quantum sensing.

Abstract

The superconducting (SC) state of magic-angle twisted bilayer graphene (MATBG) shows exceptional properties, as it consists of an unprecedentedly small electron (hole) ensemble of only ~ 10 power 11 carriers per square centimeter, which is five orders of magnitude lower than in traditional superconductors. This results in an ultra-low electronic heat capacity and kinetic inductance of this truly two-dimensional SC, and provides record-breaking key parameters for a variety of quantum sensing applications, in particular in thermal sensing and single photon detection (SPD), which traditionally exploit thermal effects in nanostructured superconducting thin films. In this work, we systematically study the interaction of the superconducting state of MATBG with individual light quanta. We discover full destruction of the SC state upon absorption of a single infrared photon even in a 16 square micrometer sized device, which showcases its exceptional bolometric sensitivity. Upon voltage biasing close to its critical current, we further show that this non-optimized device can be used as a SPD, whose click-rate is proportional to the number of absorbed photons, following Poissonian statistics. Our work offers insights into the MATBG-photon interaction and shows up pathways to use low-carrier density graphene-based superconductors as a new platform for developing revolutionary new quantum devices and sensors.