Exact magnetic field control of nitrogen-vacancy center spin for realizing fast quantum logic gates

TL;DR

This paper derives an exact analytical solution for controlling nitrogen-vacancy center spins in diamond using time-dependent magnetic fields, enabling fast and high-fidelity quantum gates for quantum computing.

Contribution

It introduces a method to precisely control NV center spins with exact solutions, facilitating rapid quantum gate implementation.

Findings

Quantum gates can be realized within a few nanoseconds.

High fidelity of quantum operations is achievable with magnetic field control.

Arbitrary qubits can be prepared from the initial 0 state.

Abstract

The negatively charged nitrogen-vacancy (NV) center spin in diamond can be used to realize quantum computation and to sense magnetic fields. Its spin triplet consists of three levels labeled with its spin z-components of +1, 0, and -1. Without external field, the +1 and -1 states are degenerate and higher than the 0 state due to the zero-field splitting. By taking the symmetrical and anti-symmetrical superpositions of the +1 and -1 states as our qubit basis, we obtain exact evolution operator of the NV center spin under time-dependent magnetic field by mapping the three-level system on time-dependent quantum two-level systems with exact analytical solutions. With our exact evolution operator of the NV center spin including three levels, we show that arbitrary qubits can be prepared from the starting 0 state and arbitrary rapid quantum logic gates of these qubits can be realized with magnetic fields. In addition, it is made clear that the typical quantum logic gates can be accomplished within a few nanoseconds and the fidelity can be very high because only magnetic field strength needs to be controlled in this approach. These results should be useful to realizing quantum computing with the NV center spin systems in diamond and exploring other effects and applications.