Evaluation of highly entangled states in asymmetrically coupled three NV centers by quantum simulator

Abstract

Despite numerous efforts, the coupling between randomly arranged multi-NV centers and also resonators has not been improved significantly mainly due to our limited knowledge of their free evolution time for entanglement (2τent). Here, we demonstrate very strong coupling between three NV centers by using a simulated triple electron-electron resonance experiment based on a quantum (UC) gate on an IBM quantum simulator with 2τent ∼12.5 μs arranged in a triangular configuration. Interestingly, through breaking, the symmetry of couplings an even lower 2τent ∼6.3 μs can be achieved. This simulation not only explains the luminescence spectra in recently observed three NV centers but also shows a large improvement of the entanglement in artificially created structures through a cyclic redistribution of couplings. Realistically disordered coupling configurations of NV center qubits with short time periods and high (0.89-0.99) fidelity of states clearly demonstrate the possibility of accurate quantum registers operated at room temperature.