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La lumière in vivo

La lumière in vivo. Igor Dotsenko Chaire de physique quantique, Collège de France Journée de l'Institut de Biologie du Collège de France Paris, 24 novembre 2009. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A. Light for exploring the nature.

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La lumière in vivo

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  1. La lumière in vivo Igor Dotsenko Chaire de physique quantique, Collège de France Journée de l'Institut de Biologie du Collège de France Paris, 24 novembre 2009 TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAA

  2. Light for exploring the nature Everyday life: Most information on our environment we obtain through light (about 80%). Science: From studies of biological cells to distant galaxies the light is the fist tool to start with. Journée de l'Institut de Biologie, 24/11/09

  3. Object of investigation H. Fizeau and L. Foucault, speed of light For many centuries, light itself was an object of interest and investigation for scientists. I. Newton, light dispersion T. Young, light interference Classical properties: electromagnetic wave with speed c, frequency n, wavelength l, etc. Journée de l'Institut de Biologie, 24/11/09

  4. Photon - intrinsically "quantum" state of light The smallest bit of light with unit energy and momentum: Non-classical, quantized photon-number states like: |exactly n photons The story of light is not over: Light is still very intriguing and fascinating object to explore !!! Quantum superposition allows more "exotic" states like (|exactly n photons +|exactly k photons ) or like: (|all photons fly left +|all photons fly right ) No way to illustrate and understand such superposition states with classical intuition ! Journée de l'Institut de Biologie, 24/11/09

  5. Catching a photon Several ways to tackle the question "How things work?" 1. observe and wonder 3. catch and have a closer look ! 2. disturb and follow Journée de l'Institut de Biologie, 24/11/09

  6. Catching a photon Fabry-Perot resonator mirror Requirements: perfect reflection off the mirrors !!! (no absorption, no transmission, no scattering) Journée de l'Institut de Biologie, 24/11/09

  7. Microwave superconducting cavity: Storage box for photons Tlight = 130 ms • a light travel distance of 39 000 km (one full turn around the Earth) • 1.4 billion bounces off the mirrors 2.8 cm 5 cm Journée de l'Institut de Biologie, 24/11/09

  8. Study light in vivo ? But, (usually) to see or explore light means to absorb it, e.g. by an eye retina or a CCD chip! Can we use a transparent (like glass) probe? Yes, use giant (Rydberg) atoms flying one-by-one across the field. 1/4 mm Journée de l'Institut de Biologie, 24/11/09

  9. Rydberg atoms Rydberg states: uniform electron distribution (i.e. no phase information) Superposition of two orbits: induced dipole rotates at atomic frequency watom (n+1) l/2 = 2pr number of oscillations (principle quantum number) Information on watom is encoded in the dipole phase  n l/2 = 2pr Journée de l'Institut de Biologie, 24/11/09

  10. Off-resonant interaction atom light • Energy conservation  the field is preserved • Atom-field interaction modifies watom proportional to n • Phase shift of the atomic dipole (relative to free atom) Phase shift per photon (depends on interaction strength) Journée de l'Institut de Biologie, 24/11/09

  11. Phase measurement: Atomic clock 1. Trigger of the atom clock: resonant pulse 2. Dephasing of the clock: interaction with the cavity field 3. Measurement of the clock: second pulse & state detection no photons 1 photon Atomic state (e/g) is correlated with number of photons (1/0) Phase shift per photon adjusted to 0 = p Journée de l'Institut de Biologie, 24/11/09

  12. Birth, life and death of a photon atoms photon number time [s] Journée de l'Institut de Biologie, 24/11/09

  13. Birth, life and death of a photon "Warm" cavity excites a thermal photon (black body radiation): (i.e. 5% of time there is one photon; from Planck's law) atoms photon number time [s] Journée de l'Institut de Biologie, 24/11/09

  14. Larger number of photons Dephasing per photon 0 < p, for instance, 0 = p/4 Distinguish up to 7 photons n = 6 n = 7 n = 0 n = 5 with probability depending on (n) n = 1 n = 4 n = 3 n = 2 Measure dipole orientation with many (~50) atoms Journée de l'Institut de Biologie, 24/11/09

  15. Seeing quantum jumps of light Quantum non-demolition measurement: Light in vivo Initial stateis classical electro-magnetic field injected from a usual microwave source (number of photons is not defined !) Random projectiononto one of n values Repeatability of QND measurement Photon number, n Quantum jumpsbetween discrete values of n: damping of the field caught in the act Journée de l'Institut de Biologie, 24/11/09

  16. Perspectives: Non-local light Cavity 1 Cavity 2 Study non-local states, e.g.: |all photons in Cavity 1, not in 2 +|all photons in Cavity 2, not in 1 What are their properties? Why not observed in our classical "macroscopic" world? Where is the transition from quantum to classical? Journée de l'Institut de Biologie, 24/11/09

  17. The cavity QED team Julien Bernu (→ Canberra) Christine Guerlin(→ Zurich) Samuel Deléglise (→ Munchen) Clément Sayrin Xingxing Zhou Bruno Peaudecerf Igor Dotsenko Sébastien Gleyzes Michel Brune Jean-Michel Raimond Serge Haroche Journée de l'Institut de Biologie, 24/11/09

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