Five-second coherence of a single spin with single-shot readout in silicon carbide

An outstanding hurdle for defect spin qubits in silicon carbide (SiC) is single-shot readout, a deterministic measurement of the quantum state. Here, we demonstrate single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defects spin state is mapped onto a long-lived charge state. With this technique, we achieve over 80% readout fidelity without pre- or postselection, resulting in a high signal-to-noise ratio that enables us to measure long spin coherence times. Combined with pulsed dynamical decoupling sequences in an isotopically purified host material, we report single-spin T-2 > 5 seconds, over two orders of magnitude greater than previously reported in this system. The mapping of these coherent spin states onto single charges unlocks both single-shot readout for scalable quantum nodes and opportunities for electrical readout via integration with semiconductor devices.
Funding Agencies|UChicago MRSEC [NSF DMR-1420709]; Pritzker Nanofabrication Facility from the SHyNE; NSFs National Nanotechnology Coordinated Infrastructure [NSF ECCS-1542205]; AFOSRUnited States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-19-1-0358]; DARPAUnited States Department of DefenseDefense Advanced Research Projects Agency (DARPA) [D18AC00015KK1932]; ONROffice of Naval Research [N00014-17-1-3026]; U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering DivisionUnited States Department of Energy (DOE); Boeing through the Chicago Quantum Exchange; JPS KAKENHI grant [21H04553, 20H00355]; Swedish Research CouncilSwedish Research CouncilEuropean Commission [20200544]; EUEuropean Commission [862721]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW 2018.0071]; University of Chicago Research Computing Center; U.S. Department of Energy Office of Science National Quantum Information Science Research CentersUnited States Department of Energy (DOE)