1. ESO seminar December 2005 Dainis Dravins Lund Observatory

2. What information is contained in light? What is being observed ? What is not ? Quantum optics in astronomy?

3. BLACKBODY --- SCATTERED --- SYNCHROTRON --- LASER --- CHERENKOV --- COHERENT --- WAVELENGTH & POLARIZATION FILTERS OBSERVER

4. BLACKBODY --- SCATTERED --- SYNCHROTRON --- LASER --- CHERENKOV --- COHERENT --- WAVELENGTH & POLARIZATION FILTERS OBSERVER

5. Intensity interferometry Narrabri stellar intensity interferomer circa 1970 (R.Hanbury Brown, R.Q.Twiss et al., University of Sydney)

6. Intensity interferometry R.Hanbury Brown, J.Davis, L.R.Allen, MNRAS 137, 375 (1967)

8. Roy Glauber Nobel prize in physics Stockholm, December 2005

9. Information content of light. I D.Dravins, ESO Messenger 78, 9 (1994)

10. Galileo’s telescopes (1609) Instruments measuring first-order spatial coherence Hubble Space Telescope (1990)

11. HARPS (2003) Fraunhofer’s spectroscope (1814) Instruments measuring first-order temporal coherence

12. Information content of light. II D.Dravins, ESO Messenger 78, 9 (1994)

13. R. Loudon The Quantum Theory of Light (2000) PHOTON STATISTICS

14. Semi-classical model of light: (a) Constant classical intensity produces photo-electrons with Poisson statistics; (b) Thermal light results in a compound Poisson process with a Bose-Einstein distribution, and ‘bunching’ of the photo-electrons (J.C. Dainty)

15. Information content of light. III D.Dravins, ESO Messenger 78, 9 (1994)

16. Quantum effects in cosmic light Examples of astrophysical lasers

17. Early thoughts about lasers in space D. Menzel : Physical Processes in Gaseous Nebulae. I, ApJ 85, 330 (1937)

18. J. Talbot Laser Action in Recombining Plasmas M.Sc. thesis, University of Ottawa (1995)

19. Hydrogen recombination lasers & masers in MWC 349A Circumstellar disk surrounding the hot star. Maser emissions occur in outer regions while lasers operate nearer to the central star.

20. Quantum effects in cosmic light Hydrogen recombination lasers & masers in MWC 349 A

21. K.H. Hofmann; Y. Balega; N.R. Ikhsanov; A.S. Miroshnichenko; G. Weigelt Bispectrum speckle interferometry of the B[e] star MWC 349A A&A 395, 891 (2002) Two-dimensional visibility of MWC 349, from speckle interferometry on the SAO 6m telescope (J-band; λ 1.24 μ m, resolution 43 mas). It appears that the star is surrounded by a circumstellar disk seen almost edge-on.

22. V. Strelnitski; M.R. Haas; H.A. Smith; E.F. Erickson; S.W. Colgan; D.J. Hollenbach Far-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A Science 272, 1459 (1996)

23. V. Strelnitski; M.R. Haas; H.A. Smith; E.F. Erickson; S.W. Colgan; D.J. Hollenbach Far-Infrared Hydrogen Lasers in the Peculiar Star MWC 349A Science 272, 1459 (1996)

24. Quantum Optics & Cosmology The First Masers in the Universe…

25. M. Spaans & C.A. Norman Hydrogen Recombination Line Masers at the Epochs of Recombination and Reionization ApJ 488, 27 (1997) FIRST MASERS IN THE UNIVERSE The black inner region denotes the evolution of the universe before decoupling. Arrows indicate maser emission from the epoch of recombination and reionization.

26. M. Spaans & C.A. Norman Hydrogen Recombination Line Masers at the Epochs of Recombination and Reionization ApJ 488, 27 (1997) Top to bottom: Three maser spots with nα = 60 produced at z  1000, if regions with density fluctuations existed at recombination. Superposed structure results from absorption during reionization. Left to right: Profiles for other frequencies along the same line of sight. Brightness temperatures  10 MK are expected.

27. Synergy OWL ― SKA SKA: Hydrogen recombination lasers in the very early Universe OWL: Hydrogen recombination lasers in the nearby Universe

28. Quantum effects in cosmic light Emission-line lasers in Eta Carinae

29. Eta Carinae HST Visual magnitude ESO VLT

30. Eta Carinae 5.5 year cyclic variation at 6 cm (Stephen White, ANTF )

31. Model of a compact gas condensation near η Car with its Strömgren boundary between photoionized (H II) and neutral (H I) regions S. Johansson & V. S. Letokhov Laser Action in a Gas Condensation in the Vicinity of a Hot Star JETP Lett. 75, 495 (2002) = Pis’ma Zh.Eksp.Teor.Fiz. 75, 591 (2002)

32. S. Johansson & V.S. Letokhov Astrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta Carinae A&A 428, 497 (2004)

33. S. Johansson & V.S. Letokhov Astrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta Carinae A&A 428, 497 (2004)

34. S. Johansson & V.S. Letokhov Astrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta Carinae A&A 428, 497 (2004)

35. Quantum effects in cosmic light Laser effects in Wolf-Rayet, symbiotic stars, & novae

36. Sketch of the symbiotic star RW Hydrae P. P. Sorokin & J. H. Glownia Lasers without inversion (LWI) in Space: A possible explanation for intense, narrow-band, emissions that dominate the visible and/or far-UV (FUV) spectra of certain astronomical objects A&A 384, 350 (2002)

37. Raman scattered emission bands in the symbiotic star V1016 Cyg H. M. Schmid Identification of the emission bands at λλ 6830, 7088 A&A 211, L31 (1989)

38. Quantum effects in cosmic light Emission from neutron stars, pulsars & magnetars

39. T.H. Hankins, J.S. Kern, J.C. Weatherall, J.A. Eilek Nanosecond radio bursts from strong plasma turbulence in the Crab pulsar Nature 422, 141 (2003)

40. A. Shearer, B. Stappers, P. O'Connor, A. Golden, R. Strom, M. Redfern, O. Ryan Enhanced Optical Emission During Crab Giant Radio Pulses Science 301, 493 (2003) Mean optical “giant” pulse (with error bars) superimposed on the average pulse

41. V.A. Soglasnov et al. Giant Pulses from PSR B1937+21 with Widths ≤ 15 Nanoseconds and T b ≥ 5×10 39 K, the Highest Brightness Temperature Observed in the Universe, ApJ 616, 439 (2004) Longitudes of giant pulses compared to the average profile. Main pulse (top); Interpulse (bottom)

42. Coherent emission from magnetars oPulsar magnetospheres emit in radio; higher plasma density shifts magnetar emission to visual & IR (= optical emission in anomalous X-ray pulsars?) oPhoton arrival statistics (high brightness temperature bursts; episodic sparking events?). Timescales down to nanoseconds suggested (Eichler et al. 2002)

43. Quantum effects in cosmic light CO 2 lasers on Venus, Mars & Earth

44. CO 2 lasers on Mars Spectra of Martian CO 2 emission line as a function of frequency difference from line center (in MHz). Blue profile is the total emergent intensity in the absence of laser emission. Red profile is Gaussian fit to laser emission line. Radiation is from a 1.7 arc second beam (half-power width) centered on Chryse Planitia. The emission peak is visible at resolutions R > 1,000,000. (Mumma et al., 1981)

45. CO 2 lasers on Earth Vibrational energy states of CO 2 and N 2 associated with the natural 10.4 μ m CO 2 laser G.M. Shved, V. P. Ogibalov Natural population inversion for the CO 2 vibrational states in Earth's atmosphere J. Atmos. Solar-Terrestrial Phys. 62, 993 (2000)

46. ”Random-laser” emission D.Wiersma, Nature,406, 132 (2000)

47. ”Random-laser” emission A “random laser” of mm-sized spheres glows with laser-like light. Monochromatic flashes are initiated by a few “lucky” photons that remain inside the material for a long time. D.Wiersma, Nature,406, 132 (2000)

48. Letokhov, V. S. Astrophysical Lasers Quant. Electr. 32, 1065 (2002) = Kvant. Elektron. 32, 1065 (2002) Masers and lasers in the active medium particle density -- medium dimension diagram

49. Quantum Optics @ Telescopes Detecting laser effects in astronomical radiation

50. Intensity interferometry Narrabri stellar intensity interferomer circa 1970 (R.Hanbury Brown, R.Q.Twiss et al., University of Sydney)

51. S.Johansson & V.S.Letokhov Possibility of Measuring the Width of Narrow Fe II Astrophysical Laser Lines in the Vicinity of Eta Carinae by means of Brown-Twiss-Townes Heterodyne Correlation Interferometry astro-ph/0501246, New Astron. 10, 361 (2005)

52. S.Johansson & V.S.Letokhov Possibility of Measuring the Width of Narrow Fe II Astrophysical Laser Lines in the Vicinity of Eta Carinae by means of Brown-Twiss-Townes Heterodyne Correlation Interferometry astro-ph/0501246, New Astron. 10, 361 (2005) Expected dependence of the correlation signal as function of (a) heterodyne frequency detuning and (b) spacing of telescopes d

53. D. Dravins 1, C. Barbieri 2 V. Da Deppo 3, D. Faria 1, S. Fornasier 2 R. A. E. Fosbury 4, L. Lindegren 1 G. Naletto 3, R. Nilsson 1, T. Occhipinti 3 F. Tamburini 2, H. Uthas 1, L. Zampieri 5 (1) Lund Observatory (2) Dept. of Astronomy, Univ. of Padova (3) Dept. of Information Engineering, Univ. of Padova (4) ST-ECF, ESO Garching (5) Astronomical Observatory of Padova

54. HIGHEST TIME RESOLUTION, REACHING QUANTUM OPTICS Other instruments cover seconds and milliseconds QUANTEYE will cover milli-, micro-, and nanoseconds, down to the quantum limit !

55. Photon statistics of laser emission If(a) If the light is non-Gaussian, photon statistics will be closer to stable wave (such as in laboratory lasers) If(b) If the light has been randomized and is close to Gaussian (thermal), photon correlation spectroscopy will reveal the narrowness of the laser light emission

56. Spectral resolution = 100,000,000 ! oTo resolve narrow optical laser emission (Δν  10 MHz) requires spectral resolution λ/Δλ  100,000,000 oAchievable by photon-correlation (“self-beating”) spectroscopy ! Resolved at delay time Δt  100 ns oMethod assumes Gaussian (thermal) photon statistics

57. Photon correlation spectroscopy E.R.Pike, in R.A.Smith, ed. Very High Resolution Spectroscopy, p.51 (1976) LENGTH & TIME FOR SPECTROMETERS OF DIFFERENT RESOLVING POWER

58. Photon correlation spectroscopy E.R.Pike, in R.A.Smith, ed. Very High Resolution Spectroscopy, p.51 (1976) LENGTH, TIME & FREQUENCY FOR TWO-MODE SPECTRUM

59. Photon correlation spectroscopy oAnalogous to spatial information from intensity interferometry, photon correlation spectroscopy does not reconstruct the shape of the source spectrum, but “only” gives linewidth information

60. SECONDS & MILLISECONDS Lunar & planetary-ring occultations Rotation of cometary nuclei Pulsations from X-ray pulsars Cataclysmic variable stars Pulsating white dwarfs Optical variability around black holes Flickering of high-luminosity stars X-ray binaries Optical pulsars Gamma-ray burst afterglows

61. MILLI-, MICRO- & NANOSECONDS Millisecond pulsars ? Variability near black holes ? Surface convection on white dwarfs ? Non-radial oscillations in neutron stars ? Surface structures on neutron-stars ? Photon bubbles in accretion flows ? Free-electron lasers around magnetars ? Astrophysical laser-line emission ? Spectral resolutions reaching R = 100 million ? Quantum statistics of photon arrival times ?

62. Binary accretion systems Artwork by Catrina Liljegren - D. Dravins, ESO Messenger 78, 9 (1994)

63. John M. Blondin (North Carolina State University) Hydrodynamics on supercomputers: Interacting Binary Stars

64. Photon Bubble Oscillations in Accretion Klein, Arons, Jernigan & Hsu ApJ 457, L85 (1996)

65. Fluctuations of Pulsar Emission with Sub-Microsecond Time-Scales J. Gil, ApSS 110, 293 (1985)

66. KUIPER-BELT OCCULTATIONS Diffraction & shadow of irregular 1-km Kuiper-belt object in front of a point star. Horizontal axes in km, vertical axis is stellar flux. Grey central spot indicates the geometrical shadow. (Roques & Moncuquet, 2000)

67. p-mode oscillating neutron star

68. Non-radial oscillations in neutron stars McDermott, Van Horn & Hansen, ApJ 325, 725 (1988)

69. PREVIOUS LIMITATIONS * CCD-like detectors: Fastest practical frame rates: 1 - 10 ms * Photon-counting detectors: Limited photon-count rates: ≳ 100 kHz

70. PRELIMINARY OPTICAL DESIGN FEASIBILITY OF CONCEPT * Slice OWL pupil into 100 segments * Focus light from each pupil segment by one in an array of 100 lenses * Detect with an array of 100 APD’s

71. Light collection with a lens array Each lens has a square aperture, 10 mm side The beam section is an annulus, with 100 mm external diameter

72. Array lens mounting concept

73. 5 x 5 array of 20 μm diameter APD detectors (SensL, Cork)

74. 32x32 Single Photon Silicon Avalanche Diode Array Quantum Architecture Group, L'Ecole Polytechnique Fédérale de Lausanne

75. “ULTIMATE” DATA RATES * 1024 x 1024 imaging elements @ 100 spectral & polarization channels * Each channel photon-counting @ 10 MHz, 1 ns time resolution * Data @ 10 15 photon time-tags per second = 1 PB/s (Petabyte, 10 15 B) = some EB/h (Exabyte = 10 18 B)

76. “REALISTIC” DATA RATES * 1024 x 1024 imaging elements one wavelength channel at a time * Each channel photon-counting @ 10 MHz with 1 ns time resolution * Data @ 10 13 photon time-tags per second = 10 TB/s (Terabyte, 10 12 B) ≈ 1 PB/min (Petabyte, 10 15 B) ≈ 1 EB/few nights (Exabyte = 10 18 B)

77. ROLE OF LARGE TELESCOPES VLT’s & ELT’s permit enormously more sensitive searches for high- speed phenomena in astrophysics Statistical functions of arriving photon stream increase with at least the square of the intensity

78. Advantages of very large telescopes Telescope diameterIntensity Second-order correlation Fourth-order photon statistics 3.6 m111 8.2 m527720 4 x 8.2 m21430185,000 50 m19337,0001,385,000,000 100 m770595,000355,000,000,000

79. INSTRUMENT DEVELOPMENT * Lund Observatory: Laboratory setup of digital intensity interferometer * Photon-counting APD’s, correlator time resolution 1.6 nanoseconds * Simulated stellar observations with two “telescopes” observing a pinhole “star”

80. Digital Intensity Interferometry Lund Observatory, December 2005

81. Photons have many properties… P HOTON O RBITAL A NGULAR M OMENTUM !

82. Photon Orbital Angular Momentum At microscopic level, interactions have been observed with helical beams acting as optical tweezers. A small transparent particle was confined away from the axis in the beam's annular ring of light. The particle's tangential recoil due to the helical phase fronts caused it to orbit around the beam axis. At the same time, the beam's spin angular momentum caused the particle to rotate on its own axis. M.Padgett, J.Courtial, L.Allen, Phys.Today May 2004, p.25

83. L.Velasco & A.Boardman, University of Salford, U.K. An electromagnetic field is expressed as a scalar complex function; where the real and the imaginary parts of the field vanish, there is an optical singularity (also called dislocation for analogy with a crystal). This singularity can be either a screw dislocation or an edge-type. The screw-type ones are optical vortices with a helicoidal wavefront.

84. Although polarization enables only two photon-spin states, photons can have many orbital-angular-momentum eigenstates, allowing single photons to encode much more information. Harwit, ApJ 597, 1266 (2003) Spin Photon Orbital Angular Momentum POAM

85. Photon Orbital Angular Momentum M.Padgett, J.Courtial, L.Allen, Phys.Today May 2004, p.25 For any given l, the beam has l intertwined helical phase fronts. For helically phased beams, the phase singularity on the axis dictates zero intensity there. The cross−sectional intensity pattern of all such beams has an annular character that persists no matter how tightly the beam is focused.

86. Max Book: Malstroem de Luxe (Galleri Engström, Stockholm)

87. Photon Orbital Angular Momentum * Individual photons can have different POAM states * Imaging with POAM-manipulated light might reveal exoplanets * Possible natural POAM sources? Rotating Kerr black holes??

88. Measuring Orbital Angular Momentum Photon orbital angular momentum produced by a spiral phase plate Martin Harwit, ApJ 597, 1266 (2003)

89. Prototype POAM experiment with fork hologram F.Tamburini, G.Umbriaco, G.Anzolin (Univ. of Padua, 2005) Thanks also to: Anton Zeilinger group, Inst. of Experimental Physics, Univ. of Vienna

90. The first three orders: ℓ=0,1,2 l=2 l=1 l=0 F.Tamburini, G.Umbriaco, G.Anzolin (University of Padua, 2005)

91. F.Tamburini, G.Umbriaco, G.Anzolin, C.Barbieri, A.Bianchini (Padua), astro-ph/0505564 FrogEye, the Quantum Coronagraphic mask. The Photon Orbital Angular Momentum and its applications to Astronomy

92. Photonic astronomy ! [Almost] all our knowledge of the Universe arrives through photons Both individual photons and photon streams are more complex than has been generally appreciated

93. Quantum Optics @ ELT’s ! Quantum optics may open a fundamentally new information channel from the Universe ! ELT’s will bring non-linear optics into astronomy !