908 research outputs found
Efficient Grover search with Rydberg blockade
We present efficient methods to implement the quantum computing Grover search
algorithm using the Rydberg blockade interaction. We show that simple pi-pulse
excitation sequences between ground and Rydberg excited states readily produce
the key conditional phase shift and inversion-about-the mean unitary operations
for the Grover search. Multi-qubit implementation schemes suitable for
different properties of the atomic interactions are identifed and the error
scaling of the protocols with system size is found to be promising for
immediate experimental investigation.Comment: Detailed description of algorithm for sub-register architecture.
Error budget modified for Cs atomic parameters. To appear in J. Phys. B.
Special Issue on Strong Rydberg interactions in ultracold atomic and
molecular gase
Deterministic entanglement of two neutral atoms via Rydberg blockade
We demonstrate the first deterministic entanglement of two individually
addressed neutral atoms using a Rydberg blockade mediated controlled-NOT gate.
Parity oscillation measurements reveal an entanglement fidelity of
, which is above the entanglement threshold of , without
any correction for atom loss, and after correcting for
background collisional losses. The fidelity results are shown to be in good
agreement with a detailed error model.Comment: 4 figure
A crossed vortex bottle beam trap for single-atom qubits
We demonstrate trapping and quantum state control of single Cesium atoms in a
532 nm wavelength bottle beam trap. The three dimensional trap is formed by
crossing two unit charge vortex beams. Single atoms are loaded with 50%
probability directly from a magneto-optical trap. We achieve a trapping
lifetime of up to 6 s, and demonstrate fast Rabi oscillations with a coherence
time of .Comment: 5 figures, minor edits to text and figures, to appear opt. let
Entanglement of two individual neutral atoms using Rydberg blockade
We report the generation of entanglement between two individual Rb
atoms in hyperfine ground states and which are held in
two optical tweezers separated by 4 m. Our scheme relies on the Rydberg
blockade effect which prevents the simultaneous excitation of the two atoms to
a Rydberg state. The entangled state is generated in about 200 ns using pulsed
two-photon excitation. We quantify the entanglement by applying global Raman
rotations on both atoms. We measure that 61% of the initial pairs of atoms are
still present at the end of the entangling sequence. These pairs are in the
target entangled state with a fidelity of 0.75.Comment: text revised, with additional reference
Independent individual addressing of multiple neutral atom qubits with a MEMS beam steering system
We demonstrate a scalable approach to addressing multiple atomic qubits for
use in quantum information processing. Individually trapped 87Rb atoms in a
linear array are selectively manipulated with a single laser guided by a MEMS
beam steering system. Single qubit oscillations are shown on multiple sites at
frequencies of ~3.5 MHz with negligible crosstalk to neighboring sites.
Switching times between the central atom and its closest neighbor were measured
to be 6-7 us while moving between the central atom and an atom two trap sites
away took 10-14 us.Comment: 9 pages, 3 figure
Rabi flopping between ground and Rydberg states with dipole-dipole atomic interactions
We demonstrate Rabi flopping of small numbers of atoms between
ground and Rydberg states with . Coherent population oscillations are
observed for single atom flopping, while the presence of two or more atoms
decoheres the oscillations. We show that these observations are consistent with
van der Waals interactions of Rydberg atoms.Comment: 4 pages, 6 figure
Rydberg state mediated quantum gates and entanglement of pairs of neutral atoms
Experiments performed within the last year have demonstrated Rydberg state
mediated quantum gates and deterministic entanglement between pairs of trapped
neutral atoms. These experiments validate ten year old proposals for Rydberg
mediated quantum logic, but are only the beginning of ongoing efforts to
improve the fidelity of the results obtained and scale the experiments to
larger numbers of qubits. We present here a summary of the results to date,
along with a critical evaluation of the prospects for higher fidelity Rydberg
gates.Comment: submitted to ICAP 2010 proceeding
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