Single Gaussian temporal pulse modulated controlled-Z gate of neutral atoms under symmetrically optical pumping

Abstract

We propose an experimentally feasible protocol for implementing the standard controlled-Z gate of neutral atoms through a symmetrical two-photon excitation process via the second resonance line, 6P in 87 Rb, with a single-Gaussian-temporal-modulation-coupling of ground state and intermediate state. For qubit states that encoded on the alkali clock states, the dynamics of system depend on different adiabatic paths modulated by Gaussian pulses, which accumulates a phase factor of π on logic qubit state |11 alone at the end of the operation. The Gaussian pulse takes the simple form of Ω0 exp[−(t − 2T ) 2 /T 2 ], and the corresponding optimal parameters can be easily determined by direct use of numerical integration. On the premise of considering only spontaneous emission, the gate fidelity can achieve 99.78% with the operation time less than 1 µs. Furthermore, we discuss in detail the impact of other sources of errors on the fidelity of logic gate and find that the use of adiabatic pulse makes the gate less sensitive to the Doppler effect and laser intensity fluctuation. By selecting suitable optical traps, the predicted fidelity of the gate can reach about 98.4% after correcting the measurement error. Compared with the existing schemes, we achieve a higher fidelity quantum logic gate through a simpler Gaussian driving field, which may be helpful to the experimental implementation of quantum computation and quantum simulation in the neutral-atoms system.