1. Witnessing Quantum Coherence IWQSE 2013, NTU Oct. 15 (2013) Yueh-Nan Chen ( 陳岳男 ) Dep. of Physics, NCKU National Center for Theoretical Sciences (South)

2. Outline Coherence and entanglement Cavity QED The Leggett-Garg Inequalities Witnessing Quantum Coherence in Biological Systems

3. Quantum Information Teleportation Dense coding Secret sharing Key distribution Quantum Computation Algorithms coherence and entanglement

4. Bit : 0, 1 or +, - or boy, girl…. Any two-level system 1 0 time t0t0 t1t1 t2t2

5. Q-bit: Any two-level and physical system (Quantum bit) 0 Two-level atom time t0t0 t1t1 t2t2 1 0 1

6. Two qbits : two spins Spin up Spin down interaction Schrodinger eq. Spin up Spin down - A B AB AB A B time t0t0 t entangled state

7. Entanglement A + a2 A ( a1 ) B + b2 B ( b1 ) Impossible to factory Symbol of connecting to independent system *.*?

8. 薛丁格的貓： To be or not to be?

9. Cavity QED

10. The Nobel Prize in Physics 2012 The Nobel Prize in Physics 2012 was awarded jointly to Serge Haroche and David J. Wineland "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems" Serge HarocheDavid J. Wineland

11. Interaction between a two-level atom and the photon reservoir: In the interaction picture, the state vector :, where : an atom initially in the excited state : a photon of q in the radiation field Spontaneous emission of single two-level atom

12. Results : where is the decay rate represents the Lamb Shift The radiation intensity distribution :, where is the energy spacing

13. Two-level atom inside a cavity The interaction between the atom and single-mode cavity:

14. J. M. Raimond, M. Brune, and S. Haroche, Rev. Mod. Phys. 73, 565 (2001). Vacuum Rabi oscillations

15. Vacuum Rabi splitting

16. Gate-confined Double Quantum Dots

17. Quantum Coherence in Double Quantum Dots

18. K. D. Petersson, J. R. Petta, H. Lu, and A. C. Gossard, PRL 105, 246804 (2010)

19. Question: Are they truly quantum?

20. The Robotic Bugs

21. Quantum vs Classical Bell’s Inequality: Locality and Realism

22. The Bell-CHSH inequality

23. Predictions of QM for the singlet state

24. QM violates the Bell-CHSH inequality

26. Leggett-Garg Inequality (Bell’s inequality in time) Realism and non-invasive measurement Quantum mechanics versus macroscopic realism: Is the flux there when nobody looks? Leggett and Garg, Phys. Rev. Lett. 54, 857–860 (1985)

28. Palacios-Laloy, A. et al. Nature Phys. 6, 442–447 (2010).

29. Distinguishing Quantum and Classical Transport through Nanostructures Transport Charge Inequality: N. Lambert, C. Emary, Y. N. Chen, and F. Nori, Phys. Rev. Lett. 105, 176801 (2010)

30. Double Quantum Dot

31. Violation of charge inequality for DQD

32. Quantum Transport in Organism ?

33. The Quantum Dimension Of Photosynthesis

37. Reaction Center Pigments (BChl) Leggett-Garg inequality ?

38. Witnessing Quantum Coherence in FMO Complex C. M. Li*, N. Lambert*, Y. N. Chen*, G. Y. Chen and F. Nori, Scientific Reports 2, 885 (2012)

39. Avian Magnetoreception: a tale of two spins

40. http://www.technologyreview.com/blog/arxiv/27829/

41. Summary 1. Coherence and Entanglement 2. Cavity QED 3. The LG Inequalities 4. Quantumness in Biological Systems

42. Thank you for your attention!