1. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Entanglement of Macroscopic Ensembles (Schroedinger’s Cat) Team: Alex Heifetz (Graduate Student) Dr. Ashish Agarwal (Post-Doc) Prof. Prem Kumar (Collaborator) Prof. Philip Hemmer (Texas A&M; collaborator) Prof. Saxena (Visitor) Supported By: DARPA, NSF

2. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science ENS 1 ENS 2 DET 1 DET 2  |g> |e> BS LASER DET 1 GENERATING ENSEMBLE ENTANGLEMENT

3. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science  |g> |e> 10 1 0 C L ADVANTAGE OF THE MACROSCOPIC APPROACH

4. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Field + Atom + Cavity e b a e b a Laser Field Cavity Mode or System

5. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Wavefunction where Initial condition before the interaction

6. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Number states Light in state a e b

7. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Hamiltonian

8. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Time evolution If we design the system such that then time evolution reduces to

9. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Laser in state Coherent State Photon distribution Coupling constant Wavefunction

10. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Classical Laser Field Cavity Mode or e b a  Result

11. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Interaction time Single Photon Detector

12. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Set-up for Entanglement generation Laser B B A A D1D1 D2D2

13. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Entangled Atomic States Conditional click in Either D 1 Or D 2 Photon Annihilation in Detector Projected Atomic State = Atom A Atom B

14. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Single Photon Detector Many Particle System

15. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Collective Enhancement Collective enhancement factor

16. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Laser B B A A D1D1 D2D2 Entanglement of atomic ensembles Conditional on detector click, Atomic ensembles are Entangled:

17. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Atomic Ensemble: 87 Rb Laser Field Raman signal F=2 F=1 6.8347 GHz P 3/2 F=2 P 3/2 F=1 P 3/2 6.8347 GHz

18. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Raman Spectroscopy Set-up Argon ion Laser Ti-Sapphire Laser Rb Heat- Pipe Oven 

19. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science Rubidium Raman Laser Argon ion Laser Ti-Sapphire Laser Rb Heat Pipe Oven PZT  Spectrum Analyzer s p p OC

20. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science TRAPPING OF LIGHT IN A Pr:YSO CRYSTAL

21. Center for Photonic Communication and ComputingMcCormick School of Engineering and Applied Science “Observation of Ultraslow and Stored Light Pulses in a Solid,” A. V. Turukhin, V.S. Sudarshanam, M.S. Shahriar, J.A. Musser, B.S. Ham, and P.R. Hemmer, Phys. Rev. Lett. 88, 023602 (2002). TRAPPING OF LIGHT IN A Pr:YSO CRYSTAL