Abstract:

First, we prepared two fivelevel Λtype atoms in ground states |g₁〉and |g₁〉.Next we let them pass through this doublemode (a mode and b mode) optical cavity. And amode couples with the transition |g〉→|e〉, bmode couples with the transition |e〉→|f〉, with the coupling strength g_a and g_b respectively. We coded the information on the polarized photon states to measure the cavity polarization states after the atoms passed through the cavity. The C-NOT gate is realized by controlling the interaction time of atoms and intracavity fields. High fidelity and low photon loss can be realized by selecting reasonable parameters. The numerical results show that to realize CNOT gate, the cavity with a strong coupling and little decay is necessary. When we set singlephoton detuning Δ=0.5g, and g/k is from 2 to 10, the fidelity can be keeping over 99%.

Key words: quantum computer, CNOT gate, cavity QED, fidelity, photon loss