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OPT 253: Quantum Optics and Quantum Information Laboratory Final Presentation

OPT 253: Quantum Optics and Quantum Information Laboratory Final Presentation . R. A. Smith II 12/10/2008 Performed with C. Gettliffe M. Lahiri. Lab 3-4: Single Photon Source. Experimental Setup. Fluorescence Lifetime Measurement. Diode-pumped solid state laser excited DiI dyle molecules

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OPT 253: Quantum Optics and Quantum Information Laboratory Final Presentation

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  1. OPT 253: Quantum Optics and Quantum Information LaboratoryFinal Presentation R. A. Smith II 12/10/2008 Performed with C. Gettliffe M. Lahiri

  2. Lab 3-4: Single Photon Source

  3. Experimental Setup

  4. Fluorescence Lifetime Measurement • Diode-pumped solid state laser excited DiI dyle molecules • λ=532nm • Pulse Separation: 13.2ns • DiI Dye Molecule Fluorescence Lifetime: τ=3.44ns • APD signal was used as a start trigger; Electric pulse from laser was used as a stop trigger

  5. EM-CCD Capture of Fluorescing Quantum Dots Acquisition time: 300ms Gain: 255 Widefield micrsocopy scan of Colloidal Quantum Dots hosted in a Cholesteric Liquid Crystal Quantum Dots illuminated with Diode-Pumped Solid State Laser

  6. Spatial Scan of Colloidal QD’s Hosted in CLC • 5μm x 5μm spatial scan of Sample of QD’s in CLC • APD 1 (top left) and APD2 (bottom left) show fluorescence of quantum dots when excited with pulsed laser • Confocal microscopy used to illuminate sample • One coordinate location of the sample was scanned temporally (above right) • Blinking confirms existence of single quantum dot

  7. Coincidence Counts of Temporal Scans • Coincidence counts of 5ms temporal scan of QD’s in CLC host • The nearly zero occurrences of zero interphoton time shows the antibunching of the photons being emitted by the QD • Antibunched photons shows single photon emission by QD

  8. Possible Improvements to Lab 3-4 • Quantum Dot Concentration

  9. Lab 2: Single Photon Interference

  10. Experiemental Setup Polarizing B/S M1 Laser Spatial Filter ND Filters 45° Polarizer EM-CCD Camera M2 Non-Polarizing B/S 45° Polarizer Young’s Double Slit Experiment M1 Laser Spatial Filter ND Filters Glass with slits EM-CCD Camera Mach-Zehnder Interferometer Setup

  11. Wave-Particle Duality • Photons exhibit both characteristics of waves and particles • Wave phenomenon is exhibited by photons when photons are not “observed” • In the presence of an observer, the photons behave as particles • Without a linear polarizer oriented at 45° at the exit of the Mach-Zehnder interferometer, the path of the photon is being observed by the system • As a result, the photons act as particles and interference is destroyed • With the polarizer in place, the photons act as waves

  12. Photon Spacing • Helium-Neon laser used • λ=633nm • Φ = 0.27μW • 9x1011 photons/s • Neutral Density Filters were used to space one photon every 100 meters • Transmission ≈ 10-6 • All pictures have a photon separation of 100 m

  13. Young’s Double Slit Experiment • Gain:0 • Acquisition time: 0.3s • Transmission: 1.57 x10-1 • 4.24x1010 photons • Gain: 255 • Acquisition time: 1.0s • Transmission: ≈1.0x10-6 • 9.0x105 photons

  14. Young’s Double Slit Experiment • Gain: 255 • Acquisition time: 20.0s • Transmission: ≈ 1.0 x10-6 • 1.80x107 photons • Gain: 255 • Acquisition time: 25.0s • Transmission: ≈ 1.0x10-6 • 2.25x107 photons

  15. Mach-Zehnder Interferometer Images • No Interference Fringes (Polarizer Removed) • Gain: 100 • Acquisition time: 0.3s • Transmission: ≈ 1.0 x10-2 • 2.70x102 photons • Interference Fringes (Polarizer Present) • Gain: 100 • Acquisition time: 0.3s • Transmission: ≈ 1.0 x10-2 • 2.70x109 photons

  16. Mach-Zehnder Interferometer Images • Interference Fringes (Polarizer Present) • Gain: 255 • Acquisition time: 1.0s • Transmission: ≈ 1.0 x10-2 • 9.0x109 photons • Interference Fringes (Polarizer Present) • Gain: 255 • Acquisition time: 5.0s • Transmission: ≈ 1.0 x10-6 • 4.50x106 photons

  17. Mach-Zehnder Interferometer Images • Interference Fringes Visibility from picture at left, maximum: 80%, minimum: 67% • Definite peaks demonstrates interference at low photon levels • Interference Fringes (Polarizer Present) • Gain: 255 • Acquisition time: 10s • Transmission: ≈ 1.0 x10-2 • 9.0x106 photons

  18. Possible Improvements to Lab 2 • Double Slit

  19. Lab 1: Entanglement and Bell’s Inequalities

  20. Entanglement Quantum State without Entanglement Entangled Quantum State • When the wave functions of two particles are coupled, or the wave functions cannot be factored apart, the particles are said to be in an entangled quantum state. • If the wave function of one state is observed, then the wave function of the second state is known

  21. Experimental Setup Mirror Laser Lens Blue Filter Quartz Plate Setup for Photographing Down-converted Photons BBO Crystals Polarizer A Polarizer B Beam Stop APD A APD B EM-CCD Camera Laser λ=363.8nm Neutral Density Filter Thick BBO Crystal Setup for Testing Bell’s Inequalities

  22. Beta Barium Borate (BBO) Crystal Down-conversion of a horizontal polarization state to two vertical polarization states Down-conversion of a vertical polarization state to two horizontal polarization states When two BBO crystals are combined, the photons that exit the second BBO crystal are in a state of quantum entanglement

  23. Cone of Down-Converted Photons Cone of Down-Converted Photons after passing through a BBO Crystal

  24. Quartz Plate Alignment Graph coincidence counts as a function of horizontal quartz plate alignment, taken 8 December 2008.

  25. Quartz Plate Alignment Graph coincidence counts as a function of vertical quartz plate alignment, taken 8 December 2008.

  26. Cosine Squared Dependence on Polarizer Angle Rotation Coincidence counts as a function of Polarizer angle from quartz plate alignment made 1 December 2008

  27. Cosine Squared Dependence on Polarizer Angle Rotation Coincidence counts as a function of Polarizer angle from quartz plate alignment made 1 December 2008

  28. Bell’s Inequality Bell’s Inequality is calculated by the following: where And N(α,β) is the number of coincidence counts for Polarizer A at angle α and Polarizer B at angle β. • If S ≤ |2|, the correlation is classical • If S ≥ |2|, the correlation violates Bell’s Inequality, implying a quantum correlation

  29. Results of Bell’s Inequality Coincidence Counts at Various Polarization Rotation Angles for quartz plate alignment from 8 December 2008 Calculation of Bell’s Inequality

  30. Possible Improvements to Lab 1 • Quartz Plate Mounting • LabView Software • Stable Alignment

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