High-fidelity spin and optical control of single silicon-vacancy centres in silicon carbide

Abstract

Scalable quantum networking requires quantum systems with quantum processing capabilities. Solid state spin systems with reliable spin–optical interfaces are a leading hardware in this regard. However, available systems suffer from large electron–phonon interaction or fast spin dephasing. Here, we demonstrate that the negatively charged silicon-vacancy centre in silicon carbide is immune to both drawbacks. Thanks to its 4 A 2 symmetry in ground and excited states, optical resonances are stable with near-Fourier-transform-limited linewidths, allowing exploitation of the spin selectivity of the optical transitions. In combination with millisecond-long spin coherence times originating from the high-purity crystal, we demonstrate high-fidelity optical initialization and coherent spin control, which we exploit to show coherent coupling to single nuclear spins with ∼1 kHz resolution. The summary of our findings makes this defect a prime candidate for realising memory-assisted quantum network applications using semiconductor-based spin-to-photon interfaces and coherently coupled nuclear spins.

Silicon carbide color centers for quantum applications

“…The main goal of these studies is to assess these color centers in terms of quantum properties, as such here we only review the emitters that present interesting potentials as a qubit or as a single-photon source or in quantum nanophotonic. The defect labeled V Si (−) known also as TV1-TV3 as reviewed in [26] is studied in [54,56,58,60,62,[69][70][71][72][73][74][75][76][77].…”

“…Due to weak PL for the V2 emission, solid immersion lens (SIL) or nanopillars are used to achieve spin optical control and ODMR with single color centers at room temperature, otherwise optical spin control can be achieved by exciting with the laser direction orthogonal to the c axis for ensemble emission [80], as this color center dipole is primarily along the c-axis. The V1 and V1′ were recently studied as a qubit, the first proving to be a better option for spin-photon interface than V2 [73,76], which is much dimmer and not always can be generated and observed. The V1 in 4H DWF is 40% [73].…”

“…Due to millisecond-long spin coherence times originating from the high-purity crystal, high-fidelity optical initialization of the spin state and its coherent spin control can be achieved. Further, it was achieved coherent coupling of the electron spins to single nuclear spins with ∼1 kHz resolution [76]. This center is currently the most promising for quantum network implementation in isotopically purified 4H SiC.…”

“…By using the V1 line of the V Si , it has been recently proven that its optical resonances are stable with near-Fourier-transform-limited linewidths, allowing single photon indistinguishability, which allows to couple its spin state selectivity to the optical transition to achieve spin-photon entanglement [76]. Single V Si have narrow, nearly lifetime-limited optical transitions that correspond to m s =±3/2 and m s =±1/2 spin states with no discernable zero-field-splitting fluctuations [80].…”

“…Schemes for spin-photon entanglement in V Si , DV and NV center in SiC defects are proposed [71]. A defect that can support spin-photon entangled interfaces in SiC has been experimentally proved so far as the V Si V2, V1 lines [76], and DV [28,85]. They possess narrow lifetime-limited optical transitions, according to a theoretical and experimental analysis by photoluminescence excitation (PLE) [70,78,80].…”