Observation of entanglement of a single photon with a trapped atom.

We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step towards long range quantum networks. To verify the entanglement, we introduce a single atom state analysis. This technique is used for full state tomography of the atom-photon qubit pair. The detection efficiency and the entanglement fidelity are high enough to allow in a next step the generation of entangled atoms at large distances, ready for a final loophole-free Bell experiment.

[1]  O. Gühne,et al.  Scalable multiparticle entanglement of trapped ions , 2005, Nature.

[2]  R. B. Blakestad,et al.  Creation of a six-atom ‘Schrödinger cat’ state , 2005, Nature.

[3]  J. Cirac,et al.  Experimental demonstration of quantum memory for light , 2004, Nature.

[4]  Thomas Legero,et al.  Quantum beat of two single photons. , 2004, Physical review letters.

[5]  A. D. Boozer,et al.  Deterministic Generation of Single Photons from One Atom Trapped in a Cavity , 2004, Science.

[6]  C. Monroe,et al.  Observation of entanglement between a single trapped atom and a single photon , 2004, Nature.

[7]  N. Vitanov,et al.  Creation and measurement of a coherent superposition of quantum states. , 2003, Physical Review Letters.

[8]  C. Simon,et al.  Robust long-distance entanglement and a loophole-free bell test with ions and photons. , 2003, Physical review letters.

[9]  J. Franson,et al.  Violation of Bell's inequality with photons from independent sources. , 2003, Physical review letters.

[10]  P Grangier,et al.  Collisional blockade in microscopic optical dipole traps. , 2002, Physical review letters.

[11]  T. Hänsch,et al.  Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms , 2002, Nature.

[12]  Jian-Wei Pan,et al.  Experimental nonlocality proof of quantum teleportation and entanglement swapping. , 2001, Physical review letters.

[13]  R Raussendorf,et al.  A one-way quantum computer. , 2001, Physical review letters.

[14]  Andrew G. White,et al.  On the measurement of qubits , 2001, quant-ph/0103121.

[15]  C. Monroe,et al.  Experimental violation of a Bell's inequality with efficient detection , 2001, Nature.

[16]  I. Chuang,et al.  Quantum Computation and Quantum Information: Bibliography , 2010 .

[17]  J. Cirac,et al.  Quantum repeaters based on entanglement purification , 1998, quant-ph/9808065.

[18]  Wolfgang Dür,et al.  Quantum Repeaters: The Role of Imperfect Local Operations in Quantum Communication , 1998 .

[19]  H. Weinfurter,et al.  Violation of Bell's Inequality under Strict Einstein Locality Conditions , 1998, quant-ph/9810080.

[20]  Pérès,et al.  Separability Criterion for Density Matrices. , 1996, Physical review letters.

[21]  M. Horodecki,et al.  Quantum α-entropy inequalities: independent condition for local realism? , 1996 .

[22]  Ekert,et al.  "Event-ready-detectors" Bell experiment via entanglement swapping. , 1993, Physical review letters.

[23]  A. Zeilinger,et al.  Speakable and Unspeakable in Quantum Mechanics , 1989 .

[24]  J. Bell,et al.  Speakable and Unspeakable in Quatum Mechanics , 1988 .

[25]  G. Roger,et al.  Experimental Test of Bell's Inequalities Using Time- Varying Analyzers , 1982 .

[26]  A. Shimony,et al.  Bell's theorem. Experimental tests and implications , 1978 .

[27]  Matison,et al.  Experimental Test of Local Hidden-Variable Theories , 1972 .

[28]  P. Pearle.  Hidden-Variable Example Based upon Data Rejection , 1970 .

[29]  A. Shimony,et al.  Proposed Experiment to Test Local Hidden Variable Theories. , 1969 .

[30]  J. Bell.  On the Einstein-Podolsky-Rosen paradox , 1964 .

[31]  Albert Einstein,et al.  Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? , 1935 .