High-fidelity quantum state transfer using Cooper-pair box qubits

• By optimizing the level anharmonicity of Cooper-pair box qubit, the fidelity of quantum state transfer can be enhanced remarkably.
• By taking advantage of the data bus and individual gate pulses, the reversible state transfer can be obtained flexibly between any pair of qubits.
• Through adjusting the microwave pulses, the desired quantum state transfer can be realized only via one-step implementation.

We propose a theoretical scheme to implement high-fidelity quantum state transfer using Cooper-pair box (CPB) qubits. By analyzing the leakage error, an appropriate system parameter is chosen to optimize the level anharmonicity of the CPB. Under the drivings of the applied microwave pulses, quantum states can be transferred reversibly between any selected pair of qubits arrayed in a circuit QED, and high fidelity of state transfer can be obtained with the accessible variables. The scheme provides a feasible approach for performing the robust state transfer in a scalable fashion.