WP1.4: Single trapped Atoms General Objectives Generate entanglement between quantum memory and single photon over large distance (several 100 m). Perform “read/write” operations via quantum teleportation protocols. Generate atom-atom entanglement over large distances (quantum repeater). Loophole-free test of Bell’s inequality M 1.4.5 Establish stable optical fiber link for long-distance applications (M27) M 1.4.6: Observation of single atoms in second mobile trap (M36) D 1.4.3: Observation of long-distance atom-photon entanglement (M30)

WP1.4: Single trapped Atoms D 1.4.3: Observation of long-distance atom-photon entanglement  M 1.4.5: Establish stable optical fiber-link for long-distance applications atom-photon correlations over 300 m atomic basis atomic basis W. Rosenfeld et al., arXiv:0808.3538v1 [quant-ph]

WP1.4: Single trapped Atoms M 1.4.6: Observation of single atoms in second mobile dipole trap  new setup Improved photon detection efficiency = 0.21 % Planning for period 4 M 1.4.7: Theoretical calculation of expected atom-atom entanglement fidelity (M 39) M 1.4.8: Observation of atom-photon entanglement in second mobile dipole trap (M 42) D 1.4.4: Observation of quantum interference of photon pairs from two trapped atoms (M 48)

WP1.5: Room-T Atomic Vapour QUANTOP Objective A Memory for a quantum state of light in an atomic ensemble of Cs atoms with a fidelity of up to 70%, had previously been demonstrated. The goal in this WP is to investigate further approaches to the memory, all based on gas in glass cells. M1.5.6 Implementation of and conclusion on storage of squeezed and entangled light states in thermal atomic ensembles – partly achieved: storage of displaced, squeezed light states two-mode storage of displaced, squeezed light states  identical to storage of two entangled states storage of one part of entangled beams D1.5.3 Application of improved fidelity storage to non-classical light states – partly achieved: storage of non-classical light states (displaced, squeezed states) improved fidelity by technical means: flat-top beam profile digital feedback improved detection efficiency improved fidelity by optimized temporal mode functions improved storage fidelity by atomic squeezing New milestones (month 42 and 48) M1.5.7 protocols for atomic - atomic state teleportation M1.5.8 technical and physical limitations to performance of atomic - atomic state teleportation New deliverable (month 48) D1.5.4 Conclusion on performance of light-to-atoms and atoms-to- atoms Hi-Fi state transfer

QUANTOP D1.5.3 Classical benchmark memory fidelity derived for a new class of states M.Owari, M.Plenio, E.Polzik, A.Serafini, M.M.Wolf, arXiv:0808:2260, accepted by NJP. Best classical fidelity vs degree ofsqueezing for arbitrary displaced states ξ-1 ξ-1 storage fidelity classical limit η – added noise in vacuum units, ξ-1 – squeezed variance

D1.5.3 Preliminary results: deterministic quantum memory for displaced squeezed states with fidelity better than classical benchmark QUANTOP light state tomography atomic state tomography 0 dB Classical benchmark 5 dB preliminary data

WP1.5: Room-T Atomic Vapour Achievements Set up components for and achieved efficient optical pumping in Cesium for state preparation Tested repeatability of optical phonon coherence measurement in bulk diamond Developed a quantum-optical interpretation of optical phonon excitations [1,2] Enhanced a paper on multimode storage using the off-resonant Raman scheme; accepted for publication [3] Characterized the Zeeman splitting inhomogeneity and Schottky-contact charging of quantum dot samples |Ψ>=|01>±|10> Pump Herald Read-out Schematic of spatial entanglement of optical phonon excitations in bulk diamond Proposed Objectives Characterize fidelity of deterministic storage and retrieval of broadband weak coherent states using an ancillary control field in Cesium vapor (# 9) Characterize and implement heralded single-phonon excitation of bulk diamond (# 12) Implement spatial entanglement of optical phonon excitations in bulk diamond (see diagram) Develop quantum dot samples with waveguides for an ensemble quantum memory [1] F. Waldermann et al., submitted to PRB. [2] F. Waldermann et al., Diam. Relat. Mater. 16, 1887-1895 (2007). [3] J. Nunn et al., Phys. Rev. A 78, 033806 (2008).

WP1.6: Cold Atoms QUANTOP Objective The general goal of this WP is to develop interfaces between light and cold atoms. In addition to a memory of single photon qubits, we want to demonstrate spin squeezing at Cs clock transition based on atom light interaction with the ultimate goal to improve the sensitivity of atom clocks. D1.6.3: Investigation of quantum properties of light coupled to the Rb BEC (due: month 24) . Partly achieved, to be continued D1.6.4: Application of atomic state tomography to excitations in quantum memories (due: month 36) . Partly achieved, to be continued M1.6.6: Assessment of decoherence rates for Rubidium and Cesium atomic samples trapped in state insensitive potentials. (due: month 30) . Partly achieved, to be continued M1.6.7: Assessment of conditional state preparation in the few excitation regime for trapped Cesium and Rubidium atomic samples; Choice of the target system (due: month 33). Partly achieved M1.6.8: Implementation of atomic state tomography on the chosen target system (due: month 36) . Partly achieved ( to be continued)

D1.6.4 Spin Squeezing and Entanglement in the Cs Clock – tomography of the nonclassical atomic state QUANTOP 3.3 dB of spectroscopically relevant pseudo-spin squeezing (projection noise corrected for decoherence from probing)

WP1.7: Comparison Comparison table Objective ALL SP1 WP1.7: Comparison Objective The objective of this WP is to compare, evaluate and analyse the different approaches to quantum memory for applications in quantum communication and computation. M1.7.4: Assessment of status of quantum memory implementation (M36) D1.7.3: Updated results on the comparison, evaluation and analysis of the different approaches to quantum memory for applications in quantum communication and computation (M36) Approaches to Quantum Memories 08 (Copenhagen: 10 - 11 July) Approaches to Quantum Memories 07 (Stuttgart: 21 - 22 June) Approaches to Quantum Memories 06 (Geneva: 29 - 30 June) Goals: Develop a common means of characterising and comparing the different quantum systems. Developing collaborations Structuring the Community Revised vision! Comparison table

Copenhagen Comparison ALL SP1

Copenhagen Comparison ALL SP1 Potential Applications Efficiency Write-in Retrieval Measure ment Entanglemt. with light Band width Storage Time MM capacity Approach Fidelity Dim. hin hout~ 0.01 10 MHz 1 ms 4 SPS, QRep LOC4 ~1 retrieval 0.97 not yet Yes with PDC RE AFC high cond. 1GHz 30 s high 10 MHz not yet SPS, QRep LOC4 RE CRIB not yet ~1 retrieval not yet high not yet Yes with PDC moderate 100 MHz 30 s not yet QRep, SPS ? ? ? ? low NV with cavity low ~1 ~0.2 ~0.2 not yet QD SPS not yet ~1 ~1 retrieval >GHz low not yet low yes 1 ms Single atoms Free space 150 ms low with cavity LHF, QRep Write 0.94 cond Read 0.9 uncond 6 MHz low ~1 h=1 low done! >ms not yet 4 ms Room-temp. gas LOC4, Prec.msmt. Write 0.7 (uncond.) Msmt 0.6 kHz h=1 low 1 high ~1 done! 200 ms 100 kHz not yet not yet not yet 1 MHz not yet Prec.msmt., LOC4, QRep h=1 Write not yet Read 0.75? moderate (spatial) Cold gas high ~1 ~1 yes 0.5 GHz 100 ms Raman gas diamond not yet not yet not yet not yet not yet SPS, QRep moderate high ~1 ~1 retrieval not yet yes GHz Cs THz diam 1 ms Cs 10 ps diam