Quantum Sensing of Single Phonons via Phonon Drag in Two-Dimensional Materials

TL;DR

This paper predicts a novel method for detecting single phonons using van der Waals heterostructures, where phonon-electron coupling induces a measurable voltage in graphene, promising advances in quantum phononics.

Contribution

It introduces a theoretical framework for phonon detection via phonon drag in 2D heterostructures, demonstrating potential for single-phonon resolution at room temperature.

Findings

Drag voltage per phonon can reach hundreds of microvolts.

Detection signal is insensitive to carrier mobility and temperature.

Method is feasible for single-phonon quantum sensing.

Abstract

The capacity to electrically detect phonons, ultimately at the single-phonon limit, is a key requirement for many schemes for phonon-based quantum computing, so-called quantum phononics. Here, we predict that by exploiting the strong coupling of their electrons to surface-polar phonons, van der Waals heterostructures can offer a suitable platform for phonon sensing, capable of resolving energy transfer at the single-phonon level. The geometry we consider is one in which a drag momentum is exerted on electrons in a graphene layer, by a single out-of-equilibrium phonon in a dielectric layer of hexagonal boron nitride, giving rise to a measurable induced voltage ($V_{\rm drag}$). Our numerical solution of the Boltzmann Transport Equation shows that this drag voltage can reach a level of a few hundred microvolts per phonon, well above experimental detection limits. Furthermore, we predict that $V_{\rm drag}$ should be highly insensitive to the mobility of carriers in the graphene layer and to increasing the temperature to at least 300 K, offering the potential of a versatile material platform for single-phonon sensing.