An energy relaxation tolerant approach to quantum entanglement, information transfer, and gates with superconducting-quantum-interference-device qubits in cavity QED

Abstract

A scheme is proposed for realizing quantum entanglement, information transfer, CNOT gates, and SWAP gates with supercoiiducting-quantum-interference-device (SQUID) qubits in cavity QED. In the scheme, the two logical states of a qubit are the two lowest levels of the SQUID. An intermediate level of the SQUID is utilized to facilitate coherent control and manipulation of quantum states of the qubits. The method presented here does not involve a real excitation of the intermediate levels during the operations. Thus, decoherence due to energy relaxation of intermediate levels is minimized. In addition, the present method does not require the adjustment of the SQUID level spacings, which simplifies the operation significantly.