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Quantum Control of the Motional and Internal Degrees of Freedom of Neutral Atoms

Jae Hoon Lee, University of Arizona

(Session 3 : Friday from 10:45am-11:15am)

Abstract. Cold trapped atoms provide an excellent platform on which to explore fundamental aspects of quantum information science, due in part to long coherence times and in part to the diverse sets of tools available for quantum manipulation. In this talk we discuss recent experimental progress towards robust quantum control of motional and ground hyperfine states of 133Cs atoms. An essential aspect of quantum information processing in optical lattices is the ability to prepare and address atoms with single-site resolution. In principle this can be done via "resonance imaging", using e. g. a combination of spatially varying light shifts and microwave pulses to change the internal state of atoms at well defined positions. In our current, first generation experiment we superimpose a long-period 1D standing wave on top of our 3D optical lattice, flip the spins of atoms in planes where the light shifted transition frequency matches that of the microwave field, and remove the remaining atoms from the lattice. Using composite pulse techniques we can make this preparation step robust against small variations in the relative position of the lattices. In a separate experiment we explore the use of DC, rf and microwave fields to manipulate the internal quantum state associated with the 16-dimensional ground hyperfine manifold of the Cs atom. Using robust control techniques, we demonstrate quantum state mapping from arbitrary initial to final states with fidelities of 98% or better, in the presence of errors and inhomogeneities in the control fields. We also study successive applications of state mapping waveforms, with the goal of separating qudit initialization and readout errors from state mapping errors, and to reliably measure state mapping fidelities in excess of 99%.