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Phys Rev Letters Cover !

Phys Rev Letters Cover !. Detecting POAM with Arecibo. Photon orbital angular momentum has never been detected from an astronomical source, but it holds great promise as a diagnostic tool. We now know how to do it with radio techniques. Arecibo is the right instrument for a first detection !.

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Phys Rev Letters Cover !

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  1. Phys Rev Letters Cover !

  2. Detecting POAM with Arecibo • Photon orbital angular momentum has never been detected from an astronomical source, but it holds great promise as a diagnostic tool. • We now know how to do it with radio techniques. • Arecibo is the right instrument for a first detection !

  3. Do it first at Arecibo! • the most sensitive single dish on the planet by a substantial margin • the best user-accessible signal processing instrumentation in the world • a long tradition of phase-coherent processing expertise: radar, ionospheric, pulsar (Hankins, ...)

  4. Astronomical potential of POAM • Martin Harwit in 2003: “POAM in Astrophysics” (ApJ, 597, 1266) • Well established physics (it has revolutionized quantum optics in the last 10 years!) • Astrophysics: wherever the orbital motion of source particles or vorticity matters (synchrotron radiation!) ...

  5. Astronomical potential of POAM ... • Some possible detection scenarios • Masers: interstellar, circumstellar, & mega-masers • Synchrotron emission with well-organized source geometry • propagation through a turbulent, ionized plasma • pulsars, quasars, SETI, ...

  6. L=0 case How to produce (or detect) POAM (Thide et al. 2007)

  7. L=0 case How to produce (or detect) POAM L = 0 case t = 0

  8. L=0 case How to produce (or detect) POAM L = 0 case t = 0 t = 0

  9. L=0 case How to produce (or detect) POAM L = 0 case t = 0 t = 0 t = 0 t = 0 t = 0 t = 0 t = 0 t = 0

  10. L=0 phase fronts Stokes parameters sufficient

  11. L=0 beam pattern

  12. L=1 case How to produce (or detect) POAM L = 1 case t = 0

  13. L=1 case How to produce (or detect) POAM L = 1 case t = 0 t = P/8

  14. L=1 case How to produce (or detect) POAM L = 1 case t = 0 t = P/8 t = P/4

  15. L=1 case How to produce (or detect) POAM L = 1 case t = 0 t = P/8 t = P/4 t = 3P/4 t = P/2

  16. L=1 phase fronts helical phase fronts! Stokes NOT sufficient

  17. L=1 beam pattern

  18. L=2 beam pattern

  19. How to detect POAMwith a single radio telescope(DRS point of view - active discussion going on) • construct a focal plane array with circular symmetry • point the telescope off-axis by a prescribed amount for each L value (not restricted to integer L values) • record the baseband signals from each of the detectors • look for the helical winding of the signal characteristic of POAM

  20. How to detect POAMwith a single radio telescope ... MORE SPECULATIVE: • detect the angular momentum content directly (torque as opposed to force on charge carriers) • in optics (Curtis & Grier, 2003, PRL) this has been seen directly: imparting orbital motion to colloidal particles! • E. Purcell “curlmeter” might be a radio technique • or transfer the POAM to the ang. momentum of a quantum liquid (B-E condensate) !!

  21. Do it first at Arecibo! • the most sensitive single dish on the planet by a substantial margin • the best user-accessible signal processing instrumentation in the world • a long tradition of phase-coherent processing expertise: radar, ionospheric, pulsar (Hankins, ...)

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