Coherent Control of Nitrogen-Vacancy Center Spins in Silicon Carbide at Room Temperature

Solid-state color centers with manipulatable spin qubits and telecom-ranged fluorescence are ideal platforms for quantum communications and distributed quantum computations. In this work, we coherently control the nitrogen-vacancy (NV) center spins in silicon carbide at room temperature, in which telecom-wavelength emission is detected. We increase the NV concentration sixfold through optimization of implantation conditions. Hence, coherent control of NV center spins is achieved at room temperature, and the coherence time $T_2$ can be reached to around $17.1\mu \mathrm{s}$. Furthermore, an investigation of fluorescence properties of single NV centers shows that they are room-temperature photostable single-photon sources at telecom range. Taking advantage of technologically mature materials, the experiment demonstrates that the NV centers in silicon carbide are promising platforms for large-scale integrated quantum photonics and long-distance quantum networks.

Figure 1

(a) The LT-PL spectra of the NV centers and divacancy defects as a function of the annealing temperature. (b) The mean counts of the scanning images ($10\times 10\mu {\mathrm{m}}^2$) as a function of the annealing temperature with a pump laser power of 1 mW. (c) The NV center ZPL intensity as a function of the annealing time at $1050°\mathrm{C}$. (d) The PL spectra of NV centers as the sample temperature increases from 20 to 300 K.

Figure 2

(a) The ODMR measurement of the NV center ($hh$) ensemble at low (bottom, 20 K) and room (top, 300 K) temperature and zero magnetic field. The red lines are the fitting using the Lorentzian function. (b) The bottom shows the ODMR measurement of the NV center ensemble at room temperature and a magnetic field of 52 G. PL6 and PL7 are divacancy defects in 4H-SiC. The three peaks in the top part correspond to the nitrogen hyperfine coupling. (c) The ODMR resonant frequencies of the NV center ensemble as a function of the axial magnetic field. (d) The spin Rabi oscillation between $|0⟩$ and $|-1⟩$ states for the $c$-axis NV centers ($hh$) at room temperature. (e) The free induction decay of the NV center spins at room temperature. The red line is the fits of the data using the decayed sinuous function [33]. (f) Hahn echo measurement of the NV center ensemble.

Figure 3

(a) The LT (20 K) PL spectra of the NV center ensemble with different implanted doses. (b) The mean counts of the NV centers on samples with different implanted doses. (c) The widths of ZPL of the NV center ($hh$) as a function of the implanted dose. (d) Comparison of the dephasing time $T_2^{*}$ for samples with four different implanted doses.

Figure 4

(a) A confocal scan image ($20\times 20\mu {\mathrm{m}}^2$) of the single NV center arrays in 4H-SiC with a laser power of 4 mW. The circled point is the investigated single NV center. The scale bar is $2\mu \mathrm{m}$. (b) The correlation function measurement of the circled single NV center in (a). (c) The lifetime of the NV center ensemble at room temperature. (d) The counts of the single NV centers as a function of the laser power. (e) The photostability of the single NV center at two different pump laser powers with the time bin set to 100 ms. (f) The ODMR measurement of a single NV center.