[9p-M111-1~11] Quantum sensing toward ultimate sensitivity

▼ [9p-M111-5] Best magnetic-field sensitivities with single NV centres at room temperature

〇Ernst David Herbschleb¹, Hiromitsu Kato², Yuichi Maruyama¹, Takuya Danjo¹, Toshiharu Makino², Satoshi Yamasaki², Izuru Ohki¹, Kan Hayashi¹, Hiroki Morishita¹, Masanori Fujiwara¹, Norikazu Mizuochi¹ (1.Kyoto Univ., 2.AIST)

Keywords:NV centre, coherence time, magnetic-field sensing

Nitrogen-vacancy (NV) centres are promising candidates for quantum sensing due to their spin, atomic size, and room-temperature operation. In our research, we measure the electron spin of NV centres in phosphorus-doped n-type diamond with enriched ¹²C. With such samples, we are able to measure the longest inhomogeneous dephasing time (T₂^* ~1.0 ms) and the longest Hahn-echo spin-coherence time (T₂ ~2.4 ms) ever observed in room-temperature solid-state systems. We find that the sensitivity, both for DC and for AC magnetic fields, is about 10 nT/Hz^1/2, which is currently the best sensitivity of a single NV centre at room temperature. Noise spectroscopy and longitudinal-relaxation measurements indicate that further improvement lies within optimising the phosphorus concentration and continuing to reduce paramagnetic impurities and defects.