High Fidelity Single-NV Qubit Quantum State Tomography by Photoelectric Readout

TL;DR

This paper demonstrates high-fidelity quantum state tomography of a single NV center using photoelectric readout, offering a promising alternative to optical methods for scalable, room-temperature quantum computing.

Contribution

It introduces and validates photoelectric detection for quantum state tomography of NV centers, achieving fidelity comparable to optical readout.

Findings

Photoelectric readout achieves 0.995 fidelity in state reconstruction.

Photoelectric detection is competitive with optical readout for NV centers.

The method supports scalable, room-temperature quantum computing architectures.

Abstract

Quantum computing is a rapidly developing field. However, the most commonly used qubits require cryogenic conditions to operate, which increases the costs and puts constraints on the up-scaling. Ambient solid-state qubits provide an alternative with potential for large-scale application. The nitrogen-vacancy (NV) center in diamond is one of the main candidates for solid-state computing architectures at room temperature and has proven to be competitive in terms of gate fidelity, quantum error correction, couplings, etc. Each NV center has an associated electronic spin that is conventionally read out by photoluminescence. However, regarding the creation of small, ambient NV-based quantum processors, the optical readout introduces limitations on the collection efficiency and resolution of the readout as well as the size of the final device and its integration into standard semiconductor architectures. In this work, we investigate the competitiveness of the photoelectric readout versus the traditional optical readout. In particular, we report on using photoelectrical detection to perform quantum state tomography measurements on a single NV center. We achieve the fidelity $0.995 \pm 0.0062$ for state reconstruction, comparable to optical measurements, demonstrating that the fidelity does not suffer from the adapted readout, highlighting the value of photoelectric detection for NV-based quantum processors.