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arXiv:0908.0454 · Physical Review Letters

Entanglement of Two Individual Neutral Atoms Using Rydberg Blockade

Tatjana Wilk, Alpha Gaétan, Charles Evellin, Janik Wolters, Y. Miroshnychenko, Philippe Grangier, Antoine Browaeys

Published Jan 8, 2010• 728 citations
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Abstract

We report the generation of entanglement between two individual 87Rb atoms in hyperfine ground states |F=1,M=1> and |F=2,M=2> which are held in two optical tweezers separated by 4 microm. 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.

DOI
10.1103/physrevlett.104.010502

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We report on our recent progress on the manipulation of single rubidium atoms trapped in optical tweezers and the generation of entanglement between two atoms, each individually trapped in neighboring tweezers. To create an entangled state of two atoms in their ground states, we make use of the Rydberg blockade mechanism. The degree of entanglement is measured using global rotations of the internal states of both atoms. Such internal state rotations on a single atom are demonstrated with a high fidelity.
Making use of the Rydberg blockade, we generate entanglement between two atoms individually trapped in two optical tweezers. In this paper, we detail the analysis of the data and show that we can determine the amount of entanglement between the atoms in the presence of atom losses during the entangling sequence. Our model takes into account states outside the qubit basis and allows us to perform a partial reconstruction of the density matrix describing the two-atom state. With this method, we extract the amount of entanglement between pairs of atoms still trapped after the entangling sequence and measure the fidelity with respect to the expected Bell state. We find a fidelity F pairs =0.74(7) for the 62% of atom pairs remaining in the traps at the end of the entangling sequence.
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Abstract We present a theoretical scheme to realize the highly entangled W state in the neutral atomic system by using the Rydberg blockade effect. Considering three neutral atoms trapped in an optical lattice with an equilateral triangle geometric configuration, we show that only one atom can be excited to the Rydberg excite state due to the Rydberg blockade effect. By choosing a non-zero detuning from the exact two-photon resonance in order to compensate for the blockade error caused by the finite interaction energy, we show that the three atoms W state can be generated. Moreover, we show that three atoms are entangled when W state is achieved with high fidelity.