提出了一种在腔QED系统中用一个五能级原子通过原子-腔共振相互作用实现三量子比特Toffoli 门的方案.在该方案中,两个量子化的腔模充当控制比特,而原子的两个低能态构成目标比特.数值结果表明,当同时考虑原子高能态的自发辐射和腔模的衰减对量子门保真度的影响时,腔场的衰减是主要的噪声来源.讨论了原子一光场耦合常数的偏差对三量子比特Toffoli门保真度的影响以及方案在实验上的可行性.
A scheme is proposed for realization of three-qubit Toffoli gate for two intracavity modes with a five-level atom through the atom-cavity resonant interaction in a cavity quantum electrodynamics system. In the presented protocol, the two quantized cavity-field modes act as the two controlling qubits and the two stable ground states of the atom form the target qubit. The numerical simulation shows that the cavity-field decay is the dominant noise source in the dissipative process when both the atomic spontaneous emission and the decay of the cavity modes are taken into account during the gate operation. The influence of the deviation of the coupling strength on fidelity of the three-qubit Toffoli gate and the experimental feasibility of our proposal are also discussed.
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