1. Phys Rev Letters Cover !

2. 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 ! Detecting POAM with Arecibo

3. 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,...) Do it first at Arecibo!

4. 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!)... Astronomical potential of POAM

5. 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,... Astronomical potential of POAM...

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

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

10. L=0 phase fronts

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 = P/2 t = 3P/4

16. L=1 phase fronts

17. L=1 beam pattern

18. L=2 beam pattern

19. 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 How to detect POAM with a single radio telescope (DRS point of view - active discussion going on)

20. 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) !! How to detect POAM with a single radio telescope...

21. 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,...) Do it first at Arecibo!