Towards infrared single-photon detection with superconducting magic-angle twisted bilayer graphene

Di Battista, Giorgio (2024): Towards infrared single-photon detection with superconducting magic-angle twisted bilayer graphene. Dissertation, LMU München: Fakultät für Physik

Abstract

Superconducting single-photon detectors are among the most advanced photodetectors available, offering unparalleled sensitivity for applications requiring high precision, such as communication, radio astronomy, quantum networks, and spectroscopy. Despite their numerous advantages, traditional superconducting materials are limited by their spectral range and sensitivity to low-energy photons. In this thesis, we propose a novel approach to advance single-photon detection by exploring the potential of moiré materials. Moiré materials are formed by vertically stacking two-dimensional layers with a slight twist angle, leading to the emergence of unique quantum phases. Specifically, we focus on magic-angle twisted bilayer graphene (MATBG), constituted by two graphene layers twisted at the so-called 'magic' angle of 1.1°. With an electron ensemble density of approximately 10^11 carriers per cm2, which is five orders of magnitude lower than that of traditional superconductors, MATBG exhibits ultralow electronic heat capacity and large kinetic inductance. These characteristics position MATBG as a groundbreaking material for quantum sensing applications, particularly in thermal sensing and single-photon detection. Our study marks the first major steps towards developing a single-photon detector based on superconducting MATBG. We have made substantial progress in fabricating high-quality MATBG devices and conducted a pioneering study to measure the bolometric effect under continuous laser heating. This allowed us to perform the first measurement of the thermal conductance in the superconducting state of MATBG. The major achievement of this thesis is a proof-of-principle experiment demonstrating the capability of detecting single photons. By illuminating the device at millikelvin temperatures with a highly attenuated laser source and voltage biasing an MATBG device near its superconducting phase transition, we successfully demonstrated near-infrared single-photon detection. Our findings highlight the exceptional sensitivity of MATBG and provide valuable insights into the interaction between MATBG and photons. This research paves the way for utilizing moiré superconductors as a groundbreaking platform for developing revolutionary quantum devices and sensors. The results of this study strongly encourage further exploration to extend single-photon detection capabilities to even lower energies using MATBG and other low-carrier density graphene-based superconductors.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 530 Physik
• Fakultäten: Fakultät für Physik
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 20. Dezember 2024
• 1. Bericht­erstatter:in: Efetov, Dmitri