1 / 24

IHP Quantum Information Trimester

Danish Quantum Optics Center University of Aarhus. QuanTOp. Niels Bohr Institute Copenhagen University. Light-Matter Quantum Interface. Eugene Polzik LECTURE 5. IHP Quantum Information Trimester. Quantum teleportation. Light – to – light

Download Presentation

IHP Quantum Information Trimester

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Danish Quantum Optics Center University of Aarhus QuanTOp Niels Bohr Institute Copenhagen University Light-Matter Quantum Interface Eugene Polzik LECTURE 5 IHP Quantum Information Trimester

  2. Quantum teleportation Light – to – light Entanglement resource – parametric downconversion process Atoms – to – atoms Entanglement resource – measurement induced entanglement of two atomic ensembles Light – atoms, etc

  3. Parametric Hamiltonian, no dissipation: Equations of motion for field operators: Hamiltonian commutes with the photon number difference operator: In photon number basis: "photon pairs" Workhorse of photon entanglement experiments!

  4. Entangled cavity modes Parameter: More accurate description : field modes in an optical resonator

  5. w + When the two fields are separated correlations – entanglement are observed: P=Im(E)=i( a+ - a) E- X- X+ X = Re(E)= a+ + a E+ P- P+ Parametric downconversion in a resonator (Optical Parametric Oscillator below threshold)

  6. - - Frequency tunable entangled light around 860nm 800MHz 107 photons per mode AOM Cavity modes LO+ AOM LO- Classical field

  7. 8 6 Entangled cavity modes 4 2 0 -2 -4 -6 -1 0 1 2 3 4 5 6 2 [dB(2 SQL)] Necessary and sufficient condition for entanglement p Phase [ Radians] ) 2 - -X + (X d Narrowband tunable entangled beams Sorensen, Schori, Polzik PRA, 2002 Degree of entanglement 0.8 – observed

  8. Einstein-Podolsky-Rosen entangled state Teleportation principle (canonical variables) L.Vaidman Demonstrated experimentally for light variables byFurusawa, Sørensen, Fuchs, Braunstein Kimble, Polzik. Science 1998

  9. e.-m. vacuum Classical benchmark fidelity for transfer of coherent states Atoms Best classical fidelity 50% K. Hammerer, M.M. Wolf, E.S. Polzik, J.I. Cirac, Phys. Rev. Lett. 94,150503 (2005),

  10. _ _ _ ix X P ip Alice Mx Dx Dp Mp Bob LOx LOp mBob vacuum In Out vacuum c rout LOV |vin> Classical teleportation Victor DV _ Victor

  11. LOV _ DV Victor _ Bob _ _ Mx Out rout mBob Mp Pump 2 ix b EPR beams ip ii Classical Information OPO LOp i Dp Pump 1 a Alice Dx c LOx In Victor |vin>

  12. 2 units of Vacuum = 4.8 dB Quantum teleportation Furusawa et al, Science, Vol 282, Issue 5389, 706-709 , 23 October 1998

  13. Classical boundary

  14. Communication networks based on continuousspin variables Operations: Light-atom teleportation Resources: local entanglement Memory Bob Memory Alice EPR pulses EPR spins Quantum channel Operation: Teleportation of atoms Resources: shared entanglement Memory Bob Classical channel Memory Alice EPR spin Alice EPR spin Bob Coherent pulse Symbols : Input-Output interaction: free space off-resonant dipole interaction • Continuous variables: • polarization state of light • spin state of atoms conditional rotation detection of light

  15. z x k=1 y Light-to-Atoms Teleportation Kuzmich, EP 2000

  16. Atoms 2 Atoms X Atoms 1 Detector Proposals: Duan, Cirac, Zoller, EP 2000 Kuzmich, EP. 2000 Teleported entangled Classical signal Teleportation of atomic states Light pulse

  17. Memory in rotating spin states - continued B B x z y 1,4 1,2 1,0 0,8 Atomic Quantum Noise 2,4 0,6 2,2 0,4 2,0 0,2 1,8 0,0 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 1,6 Atomic density [arb. units] Atomic noise power [arb. units]

  18. Teleportation of an entangled atomic state • Every measurement changes the single cell • spin, BUT does not change the measured sum • Every pulse measures both y and z components of the sum – entanglement is created To complete teleportation of entanglement onto cell 1 and cell 4: rotate spin 4 by A+B+C:

  19. Tripartite entanglement For atomic ensembles via quantum measurement: simple step from 2 to 3 N atoms, spins up N/2 atoms, spins down N/2 atoms, spins down Fan HY, Jiang NQ, Lu HL Lance AM, Symul T, Bowen WP, et al. Van Look et al

  20. 2 1 3 N and S condition for 3-party pairwise entanglement:

  21. Coupling strength of the interface z y x Initial coherent spin state: Spin squeezed state Measurement on light results in distribution degree of squeezing in Jz Figure of merit for the quantum interface Z Duan, Cirac, Zoller, EP PRL (2000)

  22. Probe scattering parameter: Figure of merit for the quantum interface

  23. 0.3 Single pass interaction 30 50 10 Spontaneous emission probability degree of entanglement + h Figure of merit for the quantum interface Spontaneous emission – the fundamental limit K. Hamerrer, K. Mølmer, E. S. Polzik, J. I. Cirac. PRA 2004, quant-ph/0312156

  24. cold atomic cloud cavity enhanced interaction • enhanced phase shift • power build-up inside cavity compensate with smaller photon number T: mirror transmission a: absorption

More Related