Logic-qubit CNOT gates in decoherence-free subspaces assisted by the nitrogen-vacancy center

Area of Science:

• Quantum Information Science
• Optics and Photonics
• Solid-State Physics

Background:

• Nitrogen-vacancy (NV) centers in diamond are promising solid-state qubits.
• Quantum gates are essential for quantum computation but susceptible to noise.
• Decoherence-free subspaces (DFSs) offer a path to robust quantum operations.

Purpose of the Study:

• To construct two-qubit controlled-not (CNOT) gates using NV centers in an optical microcavity.
• To achieve high-fidelity quantum gates resistant to specific noise types.
• To demonstrate a scalable approach for quantum information processing.

Main Methods:

• Utilizing an optical microcavity coupled to a nitrogen-vacancy (NV) center.
• Implementing CNOT gates within decoherence-free subspaces (DFSs).
• Employing a heralded function for error filtering and a waveform corrector (WFC) for amplitude balancing.

Main Results:

• Successfully constructed two CNOT gates operating in orthogonal DFSs.
• Demonstrated robustness against collective-rotating and collective-dephasing noise.
• Achieved high-fidelity gate operations through noise suppression techniques.

Conclusions:

• The proposed NV-center-based optical microcavity system enables robust quantum gate construction.
• The heralded function and WFC are effective in enhancing gate fidelity.
• This work presents a scalable and high-performance platform for quantum information processing.