Individual Control and Readout of Qubits in a Sub-Diffraction Volume

TL;DR

This paper demonstrates super-resolution control and readout of individual NV center qubits within a sub-diffraction cluster, enabling precise quantum measurements with minimal crosstalk, advancing quantum technology applications.

Contribution

It introduces a spectrally distinguishable excitation method for individual qubit control in dense NV center clusters, overcoming super-resolution limitations without destroying nearby qubits.

Findings

Achieved nanometer-scale localization of NV centers.

Demonstrated individual spin control and readout with low crosstalk.

Enabled high-speed quantum measurements in mesoscopic spin clusters.

Abstract

Medium-scale ensembles of coupled qubits offer a platform for near-term quantum technologies including computing, sensing, and the study of mesoscopic quantum systems. Atom-like emitters in solids have emerged as promising quantum memories, with demonstrations of spin-spin entanglement by optical and magnetic interactions. Magnetic coupling in particular is attractive for efficient and deterministic entanglement gates, but raises the problem of individual spin addressing at the necessary nanometer-scale separation. Current super-resolution techniques can reach this resolution, but are destructive to the states of nearby qubits. Here, we demonstrate the measurement of individual qubit states in a sub-diffraction cluster by selectively exciting spectrally distinguishable nitrogen vacancy (NV) centers. We demonstrate 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 $4\times10^{-2}$. 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.