Solid-State Optimal Phase-Covariant Quantum Cloning Machine

TL;DR

This paper demonstrates an experimental realization of an optimal phase-covariant quantum cloning machine using a single electron spin in a diamond defect center, achieving high fidelity at room temperature.

Contribution

The first experimental implementation of an optimal phase-covariant quantum cloning machine in a solid-state system at room temperature.

Findings

Achieved an average fidelity of 85.2%, close to the theoretical maximum of 85.4%.

Fidelity surpasses the universal cloning bound of 83.3%.

Utilized a nitrogen-vacancy defect center in diamond for encoding and control.

Abstract

Here we report an experimental realization of optimal phase-covariant quantum cloning machine with a single electron spin in solid state system at room temperature. The involved three states of two logic qubits are encoded physically in three levels of a single electron spin with two Zeeman sub-levels at a nitrogen-vacancy defect center in diamond. The preparation of input state and the phase-covariant quantum cloning transformation are controlled by two independent microwave fields. The average experimental fidelity reaches 85.2% which is very close to theoretical optimal fidelity 85.4% and is beyond the bound 83.3% of universal cloning.