A promising building block for room-temperature quantum computing is the nitrogen-vacancy (NV) center The nitrogen-vacancy (NV) center consists of a substitutional nitrogen atom and an adjacent vacancy in diamond can feature near-unity quantum efficiency, a homogeneous line width, and long electronic spin decoherence time at room-temperature.
Readout of spin state and single qubit gating have been achieved in optical fashion in individual NV centers, and quantum information swapping and entanglement are available between electronic and the nuclear spins. However, scalability is the main obstacle in such a system because entanglement of NV centers in distant diamonds has never been accomplished experimentally. This work is attempt to resolve the problem of scalable entanglement.
Arxiv – One-step implementation of multi-qubit conditional phase gating with nitrogen-vacancy centers coupled to a high-Q silica microsphere cavity
The diamond nitrogen-vacancy (NV) center is an excellent candidate for quantum information processing, whereas entangling separate NV centers is still of great experimental challenge. We propose an one-step conditional phase flip with three NV centers coupled to a whispering-gallery mode cavity by virtue of the Raman transition and smart qubit encoding. As decoherence is much suppressed, our scheme could work for more qubits. The experimental feasibility is justified.
We study a potential idea to entangle separate NV centers using the quantized whispering-gallery mode (WGM) of a fused-silica high-Q microsphere cavity. So far there has been much development in WGM cavities with, such as the microtoroidal, microcylinders, microdisks, and microspheres. Especially, microsphere cavity had gained widespread attention because of their ultrahigh Q factor (10^8 even up to 10^10), very small volume (Vm <= 100 μm^3) and simple fabrication technique.