Long coherence time of spin qubits in $^{12}$C enriched polycrystalline CVD diamond

TL;DR

This study demonstrates that $^{12}$C-enriched polycrystalline CVD diamond can host NV centers with coherence times exceeding 2 ms, comparable to single-crystal diamonds, promising for quantum applications.

Contribution

The paper reports the synthesis of high-quality $^{12}$C-enriched polycrystalline diamond with coherence properties similar to single crystals, enabling scalable quantum devices.

Findings

NV centers in polycrystalline diamond exhibit $T_2 > 2 ms

Coherence times are comparable to single-crystal diamonds

Polycrystalline material offers scalable quantum platform

Abstract

Single defects in diamond and especially negatively charged nitrogen vacancy (NV) centers are very promising quantum systems with wide applications in physics and biology. It was shown that their coherence properties can be strongly improved by growing ultrapure diamond with low concentration of parasitic spins associated with nitrogen electron spins and nuclear spins related to $^{13}$C carbon isotope. Here we report a high quality $^{12}$C-enriched polycrystalline CVD diamond material with properties comparable with single crystals. We find single NVs in the grains of this material, which show extremely long electron spin coherence time $T_2 > 2\,ms$.