Fundamental limits of neutral atom entanglement using Rydberg dressing

The Rydberg blockade phenomenon has been used to entangle neutral Rubidium, Cesium, Strontium and Ytterbium atoms. Adiabatic Rydberg dressing, involving an adiabatic passage from ground states to Rydberg states and back, is a way of introducing the interaction energy of Rydberg atoms to ground state atoms to generate ground state entanglement with direct Rydberg excitation. Recently, we showed that adiabatic Rydberg dressing using one-photon transition from ground to Rydberg states and spin echo can be used to implement a Mølmer-Sørensen gate for neutral atoms that is robust to many experimental imperfections. We extend the analysis to study the implementation of rapid adiabatic passage using a two-photon transition, which does not require the use of an ultra-violet laser, and is easier to implement experimentally. We also study the fundamental limits to entanglement generation using the adiabatic Rydberg dressing paradigm and its scaling with Rabi frequency, detuning, interaction energy and Rydberg state lifetime. Finally, we explore the forces between Rydberg dressed atoms and find that the effective soft-core potential between Rydberg dressed ground states leads to negligible forces. We find that entangling gate fidelities comparable to the one-photon excitation are achievable with the two-photon excitation with experimental imperfections, providing a more experimentally-feasible approach to obtain high fidelity and robust gates for neutral atom-based quantum computation.