Enhancement of quantum coherence in solid-state qubits via interface engineering

TL;DR

This paper demonstrates that interface engineering with oxygen termination and graphene patching significantly extends the coherence times of shallow NV centers in diamond, enhancing their quantum sensing capabilities.

Contribution

It introduces a novel interface engineering method that prolongs NV center coherence and improves sensitivity for nanoscale magnetic resonance.

Findings

NV coherence extended to over 1 ms

Enhanced detection of weakly coupled nuclear spins

Surface charge transfer reduces spin noise

Abstract

Shallow nitrogen-vacancy (NV) centers in diamond are promising quantum sensors but suffer from noise-induced short coherence times due to bulk and surface impurities. We present interfacial engineering via oxygen termination and graphene patching, extending shallow NV coherence to over 1 ms, approaching the T1 limit. Raman spectroscopy and density-functional theory reveal surface termination-driven graphene charge transfer reduces spin noise by pairing surface electrons, supported by double electron-electron resonance spectroscopy showing fewer unpaired spins. Enhanced sensitivity enables detection of single weakly coupled 13C nuclear spins and external 11B spins from a hexagonal boron nitride (h-BN) layer, achieving nanoscale nuclear magnetic resonance. A protective h-BN top layer stabilizes the platform, ensuring robustness against harsh treatments and compatibility with target materials. This integrated approach advances practical quantum sensing by combining extended coherence, improved sensitivity, and device durability.