Magic-angle bilayer graphene nano-calorimeters -- towards broadband, energy-resolving single photon detection

TL;DR

This paper introduces a superconducting magic-angle twisted bilayer graphene device capable of detecting ultra-low energy single photons across a broad spectrum, with high energy resolution and fast response, promising advancements in quantum sensing and astronomy.

Contribution

The study demonstrates for the first time that MAG can be used as a highly sensitive, broadband single photon detector exploiting its low heat capacity and sharp superconducting transition.

Findings

Detects single photons from visible to sub-THz frequencies

Response time around 4 nanoseconds

Energy resolution better than 1 THz

Abstract

Because of the ultra-low photon energies in the mid-infrared and terahertz frequencies, in these bands photodetectors are notoriously underdeveloped, and broadband single photon detectors (SPDs) are non-existent. Advanced SPDs exploit thermal effects in nano-structured superconductors, and their performance is currently limited to the more energetic near-infrared photons due to their high electronic heat capacity. Here, we demonstrate a superconducting magic-angle twisted bilayer graphene (MAG) device that is capable of detecting single photons of ultra-low energies by utilizing its record-low heat capacity and sharp superconducting transition. We theoretically quantify its calorimetric photoresponse and estimate its detection limits. This device allows the detection of ultra-broad range single photons from the visible to sub-THz with response time around 4 ns and energy resolution better than 1 THz. These attributes position MAG as an excep-tional material for long-wavelength single photon sensing, which could revolutionize such disparate fields as quantum information processing and radio astronomy.