Identification and Creation of the Room-Temperature Coherently Controllable ST1 Spin Center in Diamond

Abstract

Among hundreds of optically active solid-state defects, very few of them hold the promise of spin qubits coherently operating at room temperature. Besides the prominent nitrogen-vacancy (NV) center in diamond, the more recently discovered ST1 center possesses advantageous electronic and spin properties such as a spin-free ground state and a large spin readout contrast (>50%) at 300 K. However, because of its unknown nature, the ST1 center was never created on demand or computed theoretically. Here, we show that both oxygen and the lattice vacancy are constituents of the ST1 center. The involvement of oxygen is unambiguously proved from two independent experiments conducted on two different samples. The creation efficiency of ST1 at 1200 °C annealing is about 10 −5 for oxygen implantation of energy 6−50 keV. The addition of vacancies followed by a thermal treatment activate further oxygen into ST1 centers, as it does for native nitrogen into NV centers. Possible ST1 configurations are discussed. The ST1 creation competes with the likely more efficient formation of OV and OVH defects. The controlled fabrication of ST1 and NV centers opens up the way to scalable room-temperature hybrid qubit systems and universal nuclear spin gates.

Investigation of oxygen-vacancy complexes in diamond by means of ab initio calculations

“…In a recent report, a systematic study has been carried out by implanting different ions into CVD diamond, and then the sample was imaged by scanning confocal microscope to monitor the presence of ST1 color center [15]. They found that the occurrence of ST1 color center is associated with the implanted oxygen ions, thus the defect should contain oxygen [15].…”

“…In a recent report, a systematic study has been carried out by implanting different ions into CVD diamond, and then the sample was imaged by scanning confocal microscope to monitor the presence of ST1 color center [15]. They found that the occurrence of ST1 color center is associated with the implanted oxygen ions, thus the defect should contain oxygen [15]. Because of the low yield of the ST1 center, it was speculated that the ST1 center should be a complex of oxygen and vacancy, and it might also contain another impurity such as hydrogen [15].…”

“…They found that the occurrence of ST1 color center is associated with the implanted oxygen ions, thus the defect should contain oxygen [15]. Because of the low yield of the ST1 center, it was speculated that the ST1 center should be a complex of oxygen and vacancy, and it might also contain another impurity such as hydrogen [15]. We note that 1 H isotope has almost 100% abundance, thus it should be manifested in the ODMR signal due to the hyperfine interaction between the 1 H nuclear spin and the electron spin.…”

“…We note that 1 H isotope has almost 100% abundance, thus it should be manifested in the ODMR signal due to the hyperfine interaction between the 1 H nuclear spin and the electron spin. It was speculated that some complex of vacancy and oxygen separated at certain distances for providing relatively small D = 1135 MHz spin-spin interaction could be also the origin of the ST1 center [15].…”

Efficiency Optimization of Ge‐V Quantum Emitters in Single‐Crystal Diamond upon Ion Implantation and HPHT Annealing

“…Color centers in diamond represent an emerging class of solid-state systems for single-photon emission, [1][2][3][4][5][6][7][8] with appealing applications in quantum-enhanced technologies, including quantum information processing and quantum sensing. [9][10][11][12][13][14][15][16][17][18] Among them, point-defects related to group-IV impurities have displayed promising properties in terms of high photon emission rate, relatively narrow spectral signatures, and spin-dependent emission properties.…”