Photon-recoil and laser-focusing limits to Rydberg gate fidelity

The authors present an analysis of the limits on two-qubit Rydberg gate fidelity set by the entanglement of internal states and center-of-mass motion due to momentum kicks from the photons from the laser pulses implementing gate operations. They also discuss an approximation which leads to simple analytic formulas that account for the momentum of the photon, atom temperature, harmonic-oscillator frequency, and atomic mass. The results give valuable guidance for designing future experiments.