1. 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 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)

2. 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: v1 [quant-ph]

3. 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)

4. 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

5. 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

6. 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

7. 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, (2007).
[3] J. Nunn et al., Phys. Rev. A 78, (2008).

8. 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)

9. 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)

10. 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: July)
Approaches to Quantum Memories 07
(Stuttgart: June)
Approaches to Quantum Memories 06
(Geneva: June)
Goals:
Develop a common means of characterising and comparing the different quantum systems.
Developing collaborations
Structuring the Community
Revised vision!
Comparison table

11. Copenhagen Comparison
ALL SP1

12. 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