Individual control and readout of qubits in a sub-diffraction volume

Medium-scale ensembles of coupled qubits offer a platform for near-term quantum technologies as well as studies of many-body physics. A central challenge for coherent control of such systems is the ability to measure individual quantum states without disturbing nearby qubits. Here, we demonstrate the measurement of individual qubit states in a sub-diffraction cluster by selectively exciting spectrally distinguishable nitrogen vacancy centers. We perform super-resolution localization of single centers with nanometer spatial resolution, as well as individual control and readout of spin populations. These measurements indicate a readout-induced crosstalk on non-addressed qubits below 4 × 10−2. This approach opens the door to high-speed control and measurement of qubit registers in mesoscopic spin clusters, with applications ranging from entanglement-enhanced sensors to error-corrected qubit registers to multiplexed quantum repeater nodes. ; National Science Foundation (U.S.) (Grant DMR-1231319) ; European Commission. Framework Programme for Research and Innovation. Marie Sklodowska-Curie Actions (Agreement 753067 OPHOCS) ; Germany. Federal Ministry of Education and Research ((BMBF, DiNOQuant, Project 13N14921) ; United States. Air Force. Office of Scientific Research. Multidisciplinary University Research Initiative (Optimal Measurements for Scalable Quantum Technologies FA9550-14-1-0052) ; United States. Air Force. Office of Scientific Research (Grant FA9550-16-1-0391)