1 Characterizing Photonic Spatial States Sebastião Pádua Physics Department - Federal University of Minas Gerais – Belo Horizonte - Brazil Paraty 2009, September Informação Quântica Enlight and Quantum Optics Laboratory

2 Outline Transfer of information from the pump beam Generation and propagation of qudits Quantum Tomography of qubits with SLM Progress in four photons production

Two photon state Angular Spectrum Transference 3 k s = k i = k p /2  s =  i = 1/2 R = (  s +  i )/2

D. Prichard, et. al, Phys. Rev. Lett. (1995 )‏

Lithography Double-slit – proof of principle M. D’Angelo, M. V. Chekhova and Y. Shih, Phy. Rev. Lett (2001).

Double slit Simple slit FIG. 4. Light intensity (a), (c) and coincidence rate (b) measured at the image plane of slits illuminated by a classical infrared light source (826 nm) in (a); by the idler beam (826 nm) in (b), with idler and signal being detected in coincidence at the image plane; and by a classical light source in the violet (413 nm) in (c). For these measurement, z´´= 9cm, z´ = 47.5 cm, the slits width are equal 89  m, the dark part of double slit measure 76  m, the lenses width are equal 0.7 mm (in the measurement of simple slit) and 0.65mm (in the measurement of double slite). Double slit Simple slit FIG. 4. Light intensity (a), (c) and coincidence rate (b) measured at the image plane of slits illuminated by a classical infrared light source (826 nm) in (a); by the idler beam (826 nm) in (b), with idler and signal being detected in coincidence at the image plane; and by a classical light source in the violet (413 nm) in (c). For these measurement, z´´= 9cm, z´ = 47.5 cm, the slits width are equal 89  m, the dark part of double slit measure 76  m, the lenses width are equal 0.7 mm (in the measurement of simple slit) and 0.65mm (in the measurement of double slite). EXPERIMENTAL RESULTS Double slit Simple slit FIG. 4. Light intensity (a), (c) and coincidence rate (b) measured at the image plane of slits illuminated by a classical infrared light source (826 nm) in (a); by the idler beam (826 nm) in (b), with idler and signal being detected in coincidence at the image plane; and by a classical light source in the violet (413 nm) in (c). For these measurement, z´´= 9cm, z´ = 47.5 cm, the slits width are equal 89  m, the dark part of double slit measure 76  m, the lenses width are equal 0.7 mm (in the measurement of simple slit) and 0.65mm (in the measurement of double slite). EXPERIMENTAL RESULTS Double slit Simple slit FIG. 4. Light intensity (a), (c) and coincidence rate (b) measured at the image plane of slits illuminated by a classical infrared light source (826 nm) in (a); by the idler beam (826 nm) in (b), with idler and signal being detected in coincidence at the image plane; and by a classical light source in the violet (413 nm) in (c). For these measurement, z´´= 9cm, z´ = 47.5 cm, the slits width are equal 89  m, the dark part of double slit measure 76  m, the lenses width are equal 0.7 mm (in the measurement of simple slit) and 0.65mm (in the measurement of double slite). OBJECT: DOUBLE SLIT Laser,  = 826 nm Laser,  = 413 nm Twin Photons  = 826 nm

Optics Communications

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15 Quantum Tomography with a Spatial Light Modulator

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17 Phases: 0, 0, -60.7, 80,6

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20 = The values of p i are obtained from measurements.

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22 = Slits are partially blocked and phases are changed by the SLM

23 LiIO3

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25 Laser He- Cd LiIO 3 M1 M2 C SLM L1 L2 Double Slit f f

26 Goal: 2 qubits and 2 qutrits.

27 Students: Juliana Gontijo, Wanderson Pimenta, Mariana Barros, Marco Aurélio Carvalho, Breno Teixeira – Physics Department - UFMG Pos-doc : Dr. José Ferraz Prof. Marcelo Terra Cunha – Mathematics Department – UFMG Univ. De Concepción - Chile: Profs. Leonardo Neves, G. Lima, A. Delgado, and Carlos Saavedra

28 PPKTP – SPDC – Type II Angular Spectrum Transference Controlling the transverse correlation in QPM parametric down- conversion, O. Cosme, A. Delgado, G. Lima, C. H. Monken and S. Pádua – arXiv: v1(2009)[quant-ph].

PPKTP Quantum image formation 29 Image of a double-slit placed in the pump beam path and detected at the image plane by coincidence

30 Profile of the laser beam and 4-photon coincidence count in the horizontal direction SPDC state with four photons- PPKTP Transfer of the pump angular spectrum to the four photon SPDC quantum state Profile of the laser beam and 4-photon coincidence count in the vertical direction

31 Image of a displaced wire in the pump beam path and 4- photon counts SPDC state with four photons- PPKTP Transfer of the pump angular spectrum to the four photon SPDC quantum state