Figure 1

(a) Atomic structure of the $\mathrm{N}\mathrm{\text{−}}V$ center in diamond [4]. (b) Fluorescence microscopy image of the single $\mathrm{N}\mathrm{\text{−}}V$ center. (c) Fluorescence autocorrelation function. (d) Energy level diagram of the electronic ground state showing the zero-field splitting. (e) Optically detected magnetic resonance spectra for the single $\mathrm{N}\mathrm{\text{−}}V$ center, where the upper and the lower curves represent, respectively, the cases with and without the external static magnetic field by a frequency sweep under 10 000 averages. Lorentzian peaks (the red lines) were fitted to the experimental spectra (black circles). (f) $T_2$ times measured by resonant transitions in the presence of an external static magnetic field, where the upper (lower) curve shows the echo decay corresponding to the transition between $|0⟩$ to $|-1⟩$ ($|1⟩$).Reuse & Permissions

Figure 2

Transient nutation of the electron spin between ground state sublevels of the single $\mathrm{N}\mathrm{\text{−}}V$ center, where the upper (lower) plot is for nutation between $|0⟩$ and $|-1⟩$ ($|1⟩$) sublevels. The experimental data (black solid circles) were fitted by a damped sine function (red line) written as $y=y_0+A{e}^{-t/T_2^{\prime }}\cos (\omega t)$, with the intensity offset $y_0$ and the amplitude $A=0.5$. The normalization is independent from $T_2^{\prime }$ and nutation frequency $\omega$. The fast Fourier transform (FFT) without windowing was applied to obtain the Rabi frequencies. (a) Nutation experiment at frequency 2.8450 GHz (${\mathrm{MW}}_1$) with $2\times {10}^6$ averages. Its FFT spectrum (c) shows a 6.58 MHz Rabi frequency. (b) Nutation experiment at frequency 2.8715 GHz (${\mathrm{MW}}_2$) with $2\times {10}^6$ averages. Its FFT spectrum (d) shows a 6.94 MHz Rabi frequency.Reuse & Permissions

Figure 3

Diagram of the experimental pulse sequences used to realize the RDJ algorithm. The 532 nm laser (green line) is used to initialize the state of the $\mathrm{N}\mathrm{\text{−}}V$ center to $|0⟩$ and is shut off during the period of running the algorithm. Then the laser is switched on again for detection. ${\mathrm{MW}}_1$ (red line) and ${\mathrm{MW}}_2$ (blue line) are two microwave channels which excite different transitions selectively. The first ${\mathrm{MW}}_1$ $\frac{\pi }{2}$ pulse is used to generate a superposition state in the qubit. The $V_{f_i}$ operations ($i=1,2,3,4$) are realized by combinations of (both ${\mathrm{MW}}_1$ and ${\mathrm{MW}}_2$) $2\pi$ pulses, as shown between the two vertical dashed lines. The detection of the result of the RDJ algorithm is realized by collecting echo data (${\tau }^{\prime }$ varied).Reuse & Permissions

Figure 4

The output of the RDJ algorithm is detected by the spin echoes. (a) and (b) with the positive echoes correspond to the constant function $V_{f_1}$ and $V_{f_2}$, respectively, while (c) and (d) with the negative echoes indicate the balanced function $V_{f_3}$ and $V_{f_4}$, respectively. Each echo has been averaged by $10\times {10}^6$ times.Reuse & Permissions