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December 10, 2008
Final Exam
Lab 1
(1)What is entanglement? How did you create polarization entangled photons in your experiment?
(2)How did you prove in your experiment that you have entangled photons?
(3)What is spontaneous parametric down conversion?
(4)Make a sketch of your experimental setup and describe its main components.
(5)For what purpose do you need a quartz plate?
(6)What are Bell’s inequalities? Can you calculate them for some classical objects? How did you calculate them in your Lab?
(7)You know that you have the quantum state . How do you expect count B to change as you rotate polarizer B from 0˚ to 360˚, but polarizer A is set for a fixed angle ?
(8)If polarizer A was removed how would you expect the coincidence count to change as you rotate polarizer B form 0˚ to 360˚? What is the difference between coincidence plot with no polarizer A and coincidence plot with the polarizer A at =0?
(9)How do you define a visibility? What would you expect the visibility to be for a perfectly flat curve? What does it mean to have a 100% visibility? What visibility should you have to violate Bell’s inequality?
(10)The predicted value of |S| from quantum theory at the angles you used in this Lab is 2.82. Discuss why you did not get this value of |S| (i.e., what are the sources of experimental errors).
(11)How does a count rate of APD detector A (singles’ count rate) depend on the angle of a polarizer A and on the angle of a polarizer B?
(12)What are the conditions for maximum and minimum coincidence count rates for setup with two polarizers in front of each APD?
Lab. 2.
(13)How many photons/s with wavelength 633 nm do you have at laser power 10 mW? What should be a filter transmission value to attenuate a 10 mW, 633 nm laser beam to a single-photon level (e.g., for a ~ 300-m distance between photons)?
(14)Will you expect to obtain antibunching from the attenuated laser beam?
(15)Explain wave-particle duality of photons in your experiments.
(16)Draw the interference pattern from a single slit and a double-slit. Provide the equations for these patterns.
(17)Draw the schematics of a Mach-Zender interferometer.
(18)How did you align the interferometer?
(19)Explain what is a “which-way information”. Explain it on the example of your experiments.
(20)Sketch on the figure below the intensity pattern you would see if the top slit is blocked.
Young’s double slit experiment with top slit blocked.
(21)If light is nothing but a stream of particles (called photons), why doesn’t a stream of bullets give rise to an interference pattern similar to that of photons?
Labs 3-4
(22)What is a single photon source? How did you produce single photons in your Lab?
(23)What is the difference between photons from single photon sources and laser light attenuated to single photon level?
(24)Give the examples of different types of emitters for single photon sources.
(25)What types of single photon counting detectors did you use in these labs?
(26)What are the main elements of a confocal microscope?
(27)If you know the NA of the objective what would be a size of the focal spot? Calculate this size for 532 nm light and NA =1.3.
(28)What is antibunching? What is the value of g(2) (0): (a) for antibunched light; (b) for classical light; (c) for laser light attenuated to the single-photon level.
(29)Make a sketch of a Hanbury Brown and Twiss interferometer.
(30)What is a fluorescence lifetime? If a fluorescence lifetime is τ, how will a transition intensity change in time?
(31)What are photonic bandgap materials?
(32) What type of liquid crystal should you take to obtain selective reflection?Describe the procedure for obtaining selective reflection from the liquid crystal layer. What parameters of liquid crystal define the wavelength of a maximum of a selective reflection band? What parameters of liquid crystal define the spectral bandwidth of a selective reflection curve? Make a plot ofa selective reflection curve of the liquid crystal sample that you prepared.