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Many-particle entanglement with Bose–Einstein condensates


The possibility of creating and manipulating entangled states of systems of many particles is of significant interest for quantum information processing; such a capability could lead to new applications that rely on the basic principles of quantum mechanics1. So far, up to four atoms have been entangled in a controlled way2,3. A crucial requirement for the production of entangled states is that they can be considered pure at the single-particle level. Bose–Einstein condensates4,5,6 fulfil this requirement; hence it is natural to investigate whether they can also be used in some applications of quantum information. Here we propose a method to achieve substantial entanglement of a large number of atoms in a Bose–Einstein condensate. A single resonant laser pulse is applied to all the atoms in the condensate, which is then allowed to evolve freely; in this latter stage, collisional interactions produce entanglement between the atoms. The technique should be realizable with present technology.

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Figure 1: Reduction in the squeezing parameter ξ2.
Figure 2: Quantum Monte Carlo simulation of squeezing in the presence of loss.


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This work was supported by the Austrian Science Foundation, the European Union project EQUIP, the TMR European network, the ESF under the PESC program “Quantum Information”, the Institute for Quantum Information GmbH, and the Thomas B. Thriges Center for Kvanteinformatik. A.S. acknowledges the hospitality of the University of Innsbruck.

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Correspondence to A. Sørensen.

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Sørensen, A., Duan, LM., Cirac, J. et al. Many-particle entanglement with Bose–Einstein condensates. Nature 409, 63–66 (2001).

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