Utilising radio OAM to study space plasma vorticity The LOIS concept and IBM software

LOFAR Solar KSP Workshop II, APS, Potsdam, Germany, 24–25 June, 2009

Utilising radio OAM to studyspace plasma vorticity

The LOIS concept and IBM softwareBo Thidé

Swedish Institute of Space Physics, IRF, and Uppsala University, Uppsala, SwedenLOIS Space Centre, Växjö, Sweden

with contributions from the LOIS OAM/radio topology collaborationJ. Bergman, S. Mohammadi, T. Leyser, E. Nordblad (Uppsala), L. Daldorff, (FMI, Helsinki),

R. Karlsson (Graz), T. Carozzi (Glasgow), H. Lundstedt (Lund), W. Löwe, W. Baan, M. Milrad (Växjö),M. Fredriksson, R. Gustavsson, N. Ibragimov, R. Khamitova. C. Svahnberg (BTH, Karlskrona),

H. Then (Oldenburg), T. Mendonca (Lisbon), Ya. N. Istomin (Lebedev Institute, Moscow),E. Weibust, B. Sjökvist (IBM Sweden), B. Elmegreen, L. Amini, A. Biem, D. Turaga,

and O. Verscheure (IBM Research, NY)

LOFAR Solar SKP Workshop II, APS. Potsdam, Germany, 24–25 June, 2009Bo Thidé 2

Early LOFAR proposals – Birth of the LOIS project


LOIS idea: Optimize LOFAR for space weather, solar physics, ionospheric turbulence and calibration...

Download from www.lois-space.net

LOFAR Solar SKP Workshop II, APS. Potsdam, Germany, 24–25 June, 2009

Fundamental question: How much physical information is embedded in EM radiation?

Bo Thidé 4

Symmetric under inhomogeneous Lorentz transformations. The concomitant Lie group is the 10-dimensional Poincaré group P(10). According to Noether’s theorem there therefore exist 10 conserved EM quantities. In fact there exist 23 exact continuous symmetries/conserved quantities (in vacuo), plus an as yet unknown number of approximate, conservation laws [Ibragimov, 2008].

Start from the beginning: the microscopic Maxwell-Lorentz equations


Conserved quantities in EM fields and matter (1)

Bo Thidé 5

Homogeneity in time => conservation of system energy (Poynting’s theorem):

Homogeneity in space => conservation of system linear momentum (gives, e.g., rise to EM Doppler shift):


Conserved quantities in EM fields an matter (2)

Bo Thidé 6

Invariance under proper Lorentz transformations => conservation of system centre of energy:

Isotropy in space => conservation of system angular momentum (gives rise to azimuthal Doppler shift):

Foundation of ‘angular momentum radio’ and vorticityprobing radio and radar methods.


Total radiated EM field angular momentum

Bo Thidé 7

For radiation beams in free space, EM field angular momentum Jem can be separated into two parts [Jackson, 1998; Thidé, 2009]:

For each single Fourier mode in real-valued representation [van Enk & Nienhuis, 1992]:

The first part is the EM spin angular momentum (SAM) Sem , a.k.a. wave polarisation, and the second part is the EM orbital angular momentum (OAM) Lem .NB: In general, both EM linear momentum pem, and EM angular momentum Jem = Lem + Sem are radiated all the way out to the far zone!

LOFAR Solar SKP Workshop II, APS. Potsdam, Germany, 24–25 June, 2009 8Bo Thidé

That far-zone POAM is generated by near-zone longitudinal E fields is well known since 1914


Micromechanical action of laser light carrying SAM and OAM

Bo Thidé 9

Spin angular momentum s = 1 Orbital angular momentum l = 8

Particles of sizes 1–3 μm irradiated by SAM/OAM laser beams

LOFAR Solar SKP Workshop II, APS. Potsdam, Germany, 24–25 June, 2009 10

EM beams on same frequency but different OAM are orthogonal and do not interfere with each other!

Bo Thidé

M. J. Padgett, J. Leach et al., U. Glasgow, UK; Royal Society

l=+1 l=+3

l= -4

Spiraling Poynting/OAM vectors carry a lot of information! The Jones matrix goes from 2×2 to 2(j+1)×2(j+1), j=s+l .


Topological degrees of freedom have revolutionised wireless communications


First observation of angular momentum in ionospheric radio emissions, Tromsø, 1983

Bo Thidé 12

Bo Thidé. Stimulated Electromagnetic Emission and nonlinear wave-wave interactions in ionospheric heating experiments. In M. Q. Tran and M. L. Sawley, editors, Proceedings, Contributed Papers, International Conference on Plasma Physics, volume I, page 131, Lausanne, Switzerland, 27 June-3 July 1984. Centre de Recherche en Physique des Plasmas, Ecole Polytechnique Federal de Lausanne, CRPP-EPFL.

O mode SEE

X mode SEE

Circular, (nearly) O-mode pumping

http://www.physics.irfu.se/Publications/Conferences/Thide:ICPP:1984.pdf




Imparting OAM onto an EM beam (laser, mm wave) with the help of a spiral plate or hologram

Bo Thidé 13


Observations at 94 GHz of angular momentum induced azimuthal (rotational ) Doppler shift

Bo Thidé 14


Use of photon orbital angular momentum (POAM) has come to the fore in astronomy and astrophysics


Europe is leading the way


Courtesy Paul Rodrigues

Deep space radar requirements


OAM spectrum probing (spiral imaging) – a new scatter radar diagnostic

Bo Thidé 18

Recent digital spiral imaging experiments (Ll. Torner et al., Opt. Express, 13, 873–881, 2005; Molina-Terriza et al., J. Eur. Opt. Soc., Rapid Publ., 2, 07014, 2007) have demonstrated that probing with OAM gives a wealth of new information about the object under study.

The stimulus…


Spiral (OAM) spectrum imaging results

Bo Thidé 19

…and its response


Linear transfer of OAM radio ↔ plasma

Bo Thidé 20

PRL, in press


Nonlinear transfer of OAM radio <-> plasma

Bo Thidé 21

Brillouin = ion lineRaman = plasma line


First unambiguous observation of Stimulated Brillouin Scattering in the ionosphere

Bo Thidé 22


First OAM/vorticity radio injection experiment in the ionospheric plasma (HAARP, Alaska, 27 Feb, 2008)


Field vector sensing means total configurability

Bo Thidé 24

Very good solar radio coronagraph!


Radio beam topology degrees of freedomLinear momentum (Poynting) flux and E vs. OAM

Bo Thidé 25

Mohammadi et al., IEEE Trans. Ant. Prop., in press, 2009

LOFAR Solar SKP Workshop II, APS. Potsdam, Germany, 24–25 June, 2009 26BoThidé

Radio beam topology degrees of freedomLeft: Conventional linear momentum (Poynting) flux and E

Right: Orbital angular momentum flux


LOIS has measured the photon spin current Vin ionospheric radio signals since 2003


LOIS resources 2003–today (total ~ 2.5 MEur)Computer cluster (two SUR grants from IBM), currently in Uppsala. To be moved to Ronneby

Radio Sweden’s 500 kW transmitter located about 100 km south of the Växjö LOIS test station and 100 km south-west of the Ronneby prototype station site. Will be used for space radar tests.

The control room at the LOIS Test Station Risinge/Växjö.

9m×8m×6m antenna chamber, Ångström Lab, Uppsala

Magnetometer, LOIS Test Station, Risinge/Växjö


New LOIS prototype site at Angelskog, RonnebyLeft photos taken 21 December, 2007, at 14:00 local time. Right photo from eniro.se


LOIS prototype station under construction in RonnebyTo be augmented by two outer, concentric rings, with 16 and 32 radio units,

respectively, for a total of 56 units with three dipoles each (funding permitting)

Bo Thidé 30


Use three orthogonal electric and magnetic antennas to sample the entire EM field vector

New generation LOIS radio sensors, to be first used at EISCAT, autumn 2009


3D vector antenna allows entirely new radio Better SNR, polarisation in real time, DOA,…

Bo Thidé 32

Click on pictures for animation! Real data from a real, live outdoor vector receiver at Ångström Lab in Uppsala. On line since 2003.

Vector coherency gives superior SNR relative to conventional scalar intensity

Instantaneous wave polarisation from one single vector antenna


LOIS prototype station sensitivity 48 tripoles=144 dipoles

Bo Thidé 33

Bo Thidé 34Swedish LOFAR Science Meeting, Stockholm, 15 January, 2009

2D LOFAR/SKA-type interferometers may exhibit polarisation aberration. 3D interferometers do not


IBM InfoSphere Streams ideal for LOIS radio data


IBM InfoSphere Streams partly developed for LOIS


InfoSphere Streams (System S) program for a distributed network of LOIS radio sensors


LOIS software developed in collaboration with IBM

Bo Thidé 38


IBM’s latest major data stream software package developed for LOIS radio data


LOIS has given rise to articles in the press

Bo Thidé 40


LOIS /LOFAR on Discovery Channel?

Bo Thidé 41


Thank you for your attention

Bo Thidé 42

....there may be more things in heaven and earth than even Maxwell had dreamt of …


EM equivalent of fluid vorticity


Phase singularities (dislocations) are to be expectedin radio beams propagating through space


Standard textbooks show that classical EM angular momentum is indeed

radiated all the way to infinity

Bo Thidé 45


Pack EM beams with much more data by utilising more topological degrees of freedom


Single photons can carry both spin angular momentum S and orbital angular momentum L!

Bo Thidé 47


Hyperentangled SAM and OAM photon states break the linear-optics channel capacity threshold

Bo Thidé 48


Shannon’s law revisited

Bo Thidé 49

Documents

Utilising radio OAM to study space plasma vorticity The LOIS concept and IBM software