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Q: Fachverband Quantenoptik und Photonik
Q 6: Quanteninformation (Atome und Ionen II)
Q 6.10: Talk
Monday, March 10, 2008, 18:45–19:00, 1B
Efficiency of entanglement of distant atoms by projective measurement — Georgina Olivares Renteria1, Stefano Zippilli1, Giovanna Morigi1, Felix Rohde2, •Carsten Schuck2, and Jürgen Eschner2 — 1Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Spain — 2ICFO - Institut de CIencies Fotoniques, 08860 Castelldefels (Barcelona), Spain
We compare the efficiency of two schemes for the preparation of entangled states of distant atoms proposed in [1,2]. In these proposals the atoms do not interact and the entanglement is realized by means of the measurement of the scattered field which project the two atoms into the desired state. We quantify the efficiency of the schemes using the fidelity between the state of the system after the detection of a photon and an ideal entangled state of the two atoms. In [1] the atoms interact with two optical cavities and the enhanced probability of emission into the cavities allows for high detection efficiency. This scheme is limited by the finite probability of emission of two photons. Thus, even under the assumption of perfect detection efficiency, the fidelity of the scheme never reaches unity. In [2] emission of two photons is suppressed by low excitation strength, but the detection efficiency is low since the atoms scatter into free space and only a small fraction of the photons is measured. In this case the fidelity is conditioned on single-photon detection and results to be higher. The comparison is quantitatively evaluated for an ongoing experiment with two distant trapped single Ca+ ions. [1] S. Bose, et al, Phys. Rev. Lett. 83, 5158 (1999). [2] C. Cabrillo, et al, Phys. Rev. A 59, 1025 (1999).