Southwest Quantum Information and Technology

Robust quantum logic gates via quantum optimal control in Rydberg dressed atoms

Presenting Author: Anupam Mitra, University of New Mexico CQuIC
Contributing Author(s): Pablo Poggi, Ivan Deutsch

The Rydberg blockade mechanism has been used to entangle two qubits encoded in the hyperfine ground manifold of neutral atoms. Thermal motion of atoms limits the gate fidelity in the standard fast-pulse protocol, which involves direct, resonant excitation to Rydberg states, as the internal atomic states and external motional states become entangled, leading to different random phases accumulated by the computational basis states. Adiabatically dressing ground and Rydberg states provides some robustness against these random phases, leaving only a residual Doppler detuning error. We analyze methods to overcome the effect of thermal motion of the atoms through quantum control techniques, combining adiabatically dressing and undressing of the hyperfine ground states with an ultraviolet laser to accumulate entangling phases and driving the atomic states with microwaves (or Raman lasers) near-resonant to the qubit transition. This protocol is amenable to further correction through quantum optimal control.

(Session 5 : Sunday from 5:00pm - 7:00pm)