Schrödinger’s Rainbow: The Renaissance in Quantum Optical Interferometry

1. Schrödinger’s Rainbow: The Renaissance in Quantum Optical Interferometry Jonathan P. Dowling Quantum Science & Technologies (QST) Group Hearne Institute for Theoretical Physics Louisiana State University http://quantum.phys.lsu.edu

2. Table of Contents • Quantum Technologies • Schrödinger’s Cat and All That • Quantum Light—Over the Rainbow • Putting Entangled Light to Work • The Yellow-Brick Roadmap

3. Quantum Atomics Ion Traps Cavity QED Linear Optics Bose-Einstein Atomic Coherence Ion Traps Quantum Optics Quantum Information Processing Quantum Mechanical Systems Coherent Quantum Electronics Superconductors Excitons Spintronics Pendulums Cantilevers Phonons Quantum Technology: The Second Quantum Revolution JP Dowling & GJ Milburn, Phil. Transactions of the Royal Soc. of London

4. Schrödinger’s Cat and All That

5. Schrödinger’s Cat Revisited

6. Quantum Kitty Review A sealed and insulated box (A) contains a radioactive source (B) which has a 50% chance during the course of the "experiment" of triggering Geiger counter (C) which activates a mechanism (D) causing a hammer to smash a flask of prussic acid (E) and killing the cat (F). An observer (G) must open the box in order to collapse the state vector of the system into one of the two possible states. A second observer (H) may be needed to collapse the state vector of the larger system containing the first observer (G) and the apparatus (A-F). And so on ...

7. Paradox? What Paradox!? (1.) The State of the Cat is “Entangled” with That of the Atom. (2.) The Cat is in a Simultaneous Superposition of Dead & Alive. (3.) Observers are Required to “Collapse” the Cat to Dead or Alive

8. Quantum Entanglement “Quantum entanglement is the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought.” — Erwin Schrödinger

9. A B Conservation of Classical Angular Momentum

10. David Bohm Entangled A B Conservation of Quantum Spin

11. Albert Einstein Boris Podolsky Nathan Rosen Einstein, Podolsky, Rosen (EPR) Paradox “If, without in any way disturbing a system, we can predict with certainty ... the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."

12. + A B A B Can the Spooky, Action-at-a-distance Predictions (Entanglement) of Quantum Mechanics… + A B A B …Be Replaced by Some Sort of Local, Statistical, Classical (Hidden Variable) Theory? Hidden Variable Theory

13. John Bell NO!—Bell’s Inequality The physical predictions of quantum theory disagree with those of any local (classical) hidden-variable theory!

14. H V Two-Photon Atomic Decay H V V H + A B A B A B V H Alain Aspect John Clauser Clauser (1978) & Aspect (1982) Experiments V= Vertical Polarization H = Horizontal Polarization

15. Quantum Light—Over the Rainbow

16. Parametric Downconversion: Type I

17. Photon Pairs Signal B UV Pump Type I Idler A , , k , , k , , k , , k w j w j + w j w j s s s i i s i i i s s s A B A B Parametric Downconversion: Type I Degenerate (Entangled) Case: ws=wi

18. Parametric Downconversion: Type I

19. Degenerate (Entangled) Case: ws=wi H V V H + A B A B B A Parametric Downconversion: Type II

21. Putting Entangled Light to Work

22. Type II Downcoversion Anton Zeilinger Alice Bob Tests of Bell’s Inequalities at Innsbruck

23. Quantum Teleportation

25. EPR Source Experiment Bell State Analysis Teleportation Experiment at Innsbruck

26. Alan Migdall NIST Heralded Photon Absolute Light Source Output characteristics : photon #  known photon timing  known wavelength  known direction  known polarization  known

27. Detector to be Calibrated Trigger or “Herald” Detector Detector Quantum Efficiency Scheme No External Standards Needed!

28. Characterizing Two-Photon Entanglement Detector PBS HWP QWP This setup allows measurement of an arbitrary polarization state in each arm. Kwiat Super-Bright Source QWP HWP PBS Detector Black Box Generates arbitrary Entangled States Paul KwiatU. Illinois Any two-photon tomography requires 16 of these measurements. Examples Arm 1Arm 2 H V H R D D

29. Characterization of Entangled States Werner States

30. System Under Lake Geneva Bob and “Charly” Share Random Crypto Key Nicolas Gisin Quantum Cryptography at University of Geneva

31. New York Times

32. The Hong-Ou-Mandel Effect Leonard Mandel

33. Quantum Optical Lithography Quantum Peak Is Narrower and Spacing is HALVED! Classical One-Photon Absorption — Classical Two-Photon Absorption — Quantum Two-Photon Absorption —

34. Image of the wave plate plane with waist=300m 33cm 3.3cm coherent beam R=0.92 0.08 + 0.92 wave plate lens f=3cm squeezed vacuum : OPA Hans Bachor Australian National University Displacement Measurements and Gravity Waves

35. A B Seth Lloyd MIT Quantum Clock Synchronization Entangled Photons Can Synchronize Past the Turbulent Atmosphere!

36. Entangled Photons are a Resource for Scalable Quantum Computation! E. Knill, R. Laflamme and G. Milburn, Nature 409, 46, (2001) Gerard Milburn University Of Queensland Quantum Controlled-NOT Gate using and Entangled-Light Source, Beam Splitters, and Detectors. Quantum Computing

38. Imaging Communications Clock Synchronization Metrology Sensors The Yellow-Brick Roadmap Computing