Giant and Tunable Bosonic Quantum Interference Induced by Two-Dimensional Metals

TL;DR

This paper reports a giant, tunable phonon-based Fano resonance in a graphene/2D Ag/SiC heterostructure, enabling ultrasensitive molecule detection and opening new avenues in quantum interference engineering with bosons.

Contribution

The study demonstrates a significantly enhanced phonon Fano resonance in a novel heterostructure, surpassing previous coupling strengths and enabling new applications in sensing and quantum technologies.

Findings

Fano asymmetry exceeds prior reports by two orders of magnitude.

Resonant scattering enhances Fano asymmetry via 2D Ag layers.

Achieved single-molecule detection using phonon Fano resonance.

Abstract

Harnessing quantum interference among bosons provides significant opportunities as bosons often carry longer coherence time than fermions. As an example of quantum interference, Fano resonance involving phonons or photons describes the coupling between discrete and continuous states, signified by an asymmetric spectral lineshape. Utilizing photon-based Fano resonance, molecule sensing with ultra-high sensitivity and ultrafast optical switching has been realized. However, phonon-based Fano resonance, which would expand the application space to a vaster regime, has been less exploited because of the weak coupling between discrete phonons with continuous states such as electronic continuum. In this work, we report the discovery of giant phonon-based Fano resonance in a graphene/2D Ag/SiC heterostructure. The Fano asymmetry, being proportional to the coupling strength, exceeds prior reports by two orders of magnitude. This Fano asymmetry arises from simultaneous frequency and lifetime matching between discrete and continuous phonons of SiC. The introduction of 2D Ag layers restructures SiC at the interface and facilitates resonant scattering to further enhance the Fano asymmetry, which is not achievable with conventional Ag thin films. With these unique properties, we demonstrated that the phonon-based Fano resonance can be used for ultrasensitive molecule detection at the single-molecule level. Our work highlights strong Fano resonance in the phononic system, opening avenues for engineering quantum interference based on bosons. Further, our findings provide opportunities for advancing phonon-related applications, including biochemical sensing, quantum transduction, and superconductor-based quantum computing.