Quantum OWL

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, University of Padova (3) Dept. of Information Engineering, Univ. of Padova (4) ST-ECF, ESO Garching (5) Astronomical Observatory of Padova

Explore parameter domains beyond those of today’s astronomy Observe what cannot be seen by imaging, photometry, spectroscopy, polarimetry, nor interferometry Open up quantum optics as another information channel from the Universe!

BLACKBODY --- SCATTERED --- SYNCHROTRON --- LASER --- CERENKOV --- COHERENT --- WAVELENGTH & POLARIZATION FILTERS OBSERVER

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

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

PHOTONS ARE COMPLEX ! ! Photon streams carry information in the temporal ordering of photon arrival times Individual photons carry orbital angular momentum, can have hundreds of states

Quantum effects in cosmic light Examples of astrophysical lasers

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

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

Circumstellar disk surrounding the hot star MWC 349. Maser emissions are thought to occur in outer regions while lasers are operating nearer to the central star.

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)

Quantum Optics & Cosmology The First Masers in the Universe…

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

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

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

Eta Carinae Mid-IR (18 μ m) images from 4-m Blanco telescope at Cerro Tololo. Field  25 arcsec

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) 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 Astrophysical lasers operating in optical Fe II lines in stellar ejecta of Eta Carinae A&A 428, 497 (2004)

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

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)

V.A. Soglasnov et al. Giant Pulses from PSR B 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)

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).

Quantum OWL Detecting laser effects in astronomical radiation

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

Photon correlation spectroscopy 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

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

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

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

R. Loudon The Quantum Theory of Light (2000) QUANTUM OPTICS

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

OWL Instrument Concept Study The Road to Quantum Optics High-Time Resolution Astrophysics

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

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 ?

p-mode oscillating neutron star

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

MAIN PREVIOUS LIMITATIONS CCD-like detectors: Fastest practical frame rates: ms Photon-counting detectors: Limited photon-count rates: ≳ 100 kHz

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

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

PRELIMINARY OPTICAL DESIGN G.Naletto, F.Cucciarrè, V.Da Deppo Dept. of Information Engineering, Univ. of Padova ISSUES * How to 1 GHz? * Large OWL images & Small APD detectors CHOSEN CONSTRAINT * Design within existing detector technologies

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

The collimator The collimator-lens system magnifies 1/60 times (collimator focal length = 600 mm, lens focal length = 10 mm), giving a nominal spot size of 50  m (1 arcsec source).

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

Array lens mounting concept

TDC-1 TDC-2 TDC-25 Control logic (FPGA) Creates the START signal for the time to digital converters from the reference clock START … … SPAD1 SPAD2 SPAD3 SPAD4 … E/O converter PLL GPS receiver H-MASERE/O Converter 20Mhz fiber 24 MHz 27bit BUS Storage 1 Reference Clock Photons START

DESIGN CHALLENGES * Imaging with GHz photon-count rates ? * Spectroscopic imaging ? * Megapixel detector arrays ?

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

INSTRUMENT DESIGN ISSUES Telescope mechanical stability ? (small and well-defined vibrations, etc.) Temporal structure of stray light ? (scattered light may arrive with systematic timelags) Atmospheric intensity scintillation ? (ELT entrance pupils are complex)

INSTRUMENTATION PHYSICS Physics of photon detection ? (photons are never studied – one studies only photoelectrons which obey other quantum statistics) Physics of photon manipulation ? (does adaptive optics affect photon statistics?) Physics of photon propagation ? (statistics change upon passing a beamsplitter)

Advantages of very large telescopes D.Dravins, L.Lindegren, E.Mezey, A.T.Young, PASP 109, 610 (1998) Atmospheric intensity scintillation

Advantages of very large telescopes Telescope diameterIntensity Second-order correlation Fourth-order photon statistics 3.6 m m x 8.2 m , m19337,0001,385,000, m770595,000355,000,000,000

Precursors to ELT’s? MAGIC 17 m diameter La Palma

Studying rapid variability Skinakas Observatory 1.3 m telescope, Oct.2004; OPTIMA (MPE) + QVANTOS Mark II (Lund)

Simulated Crab pulsar observations with MAGIC

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Photons have many properties… ORBITAL ANGULAR MOMENTUM !

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.

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

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

Prototype POAM instrument F. Tamburini, G. Umbriaco, G. Anzolin Univ. of Padova

The Fork Hologram Thanks to: Anton Zeilinger group Institute of Experimental Physics University of Vienna

The first three orders: l=0,1,2 l=2 l=1 l=0

The End