quantum optics lab reviejustin justin winkler winkler. lab 1 entanglement and bell’s inequalities....
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Quantum Optics Lab ReviewQuantum Optics Lab Review
Justin Justin WinklerWinkler
Lab 1Lab 1
Entanglement and Bell’s Entanglement and Bell’s Entanglement and Bell’s Entanglement and Bell’s
InequalitiesInequalities
EntanglementEntanglement
�� WaveWave--functions are nonfunctions are non--separableseparable
�� Measurement of state of one particle alters the Measurement of state of one particle alters the �� Measurement of state of one particle alters the Measurement of state of one particle alters the
state of the other particlestate of the other particle
�� Entanglement proposed in EPR paper (1935)Entanglement proposed in EPR paper (1935)
�� Believed this couldn’t happenBelieved this couldn’t happen
�� Bell’s inequalities show occurrence of Bell’s inequalities show occurrence of
entanglement (proposed by J. S. Bell, 1964)entanglement (proposed by J. S. Bell, 1964)
Bell’s InequalityBell’s Inequality
�� Inequality does not describe any particular Inequality does not describe any particular
physical quantityphysical quantity
�� Trivially satisfied for classical objectsTrivially satisfied for classical objects
�� Bell’s inequalities allow experimental testing of Bell’s inequalities allow experimental testing of �� Bell’s inequalities allow experimental testing of Bell’s inequalities allow experimental testing of
interpretation of quantum mechanicsinterpretation of quantum mechanics
�� Bell’s theorem Bell’s theorem –– no theory of local hidden no theory of local hidden
variables can fully reproduce the predictions of variables can fully reproduce the predictions of
quantum mechanicsquantum mechanics
TheoryTheory
Measured and Theoretical Measured and Theoretical
ProbabilitiesProbabilities
CSHS InequalityCSHS Inequality
Quantum mechanics predicts violation at certain Quantum mechanics predicts violation at certain
angles, allowing a maximum S value of 2.82843angles, allowing a maximum S value of 2.82843
Experimental SetupExperimental Setup
Coincident Photon CountsCoincident Photon Counts
�� Polarizer A held constant, polarizer B rotatedPolarizer A held constant, polarizer B rotated
�� Expected cosine squared dependenceExpected cosine squared dependence
Bell’s inequality was violatedBell’s inequality was violated
Predicted S = 2.828Predicted S = 2.828
Additional ResultsAdditional Results
Predicted S = 2.497Predicted S = 2.497
Lab 2: Single Photon InterferenceLab 2: Single Photon InterferenceLab 2: Single Photon InterferenceLab 2: Single Photon Interference
Lab 2 StructureLab 2 Structure
�� Two PartsTwo Parts
�� Double Slit DiffractionDouble Slit Diffraction
��WaveWave--Particle DualityParticle Duality
��Single photon diffractionSingle photon diffraction��Single photon diffractionSingle photon diffraction
��Used attenuated laser sourceUsed attenuated laser source
�� MachMach--ZehnderZehnder InterferometerInterferometer
��WhichWhich--way informationway information
��Also used attenuated laser sourceAlso used attenuated laser source
Double Slit DiffractionDouble Slit Diffraction
Diffraction PatternDiffraction Pattern
WaveWave--Particle DualityParticle Duality
�� Light has waveLight has wave--like and particlelike and particle--like propertieslike properties
�� WaveWave
�� DiffractionDiffraction
�� InterferenceInterference�� InterferenceInterference
�� ParticleParticle
�� Photoelectric effectPhotoelectric effect
�� PhotonsPhotons
�� AntibunchingAntibunching
�� Single photons are still expected to display Single photons are still expected to display
interference effectsinterference effects
Double Slit ApparatusDouble Slit Apparatus
Double Slit ResultsDouble Slit Results
�� 4 orders of 4 orders of
attenuationattenuation
�� Average of 0.94 Average of 0.94
meters between meters between meters between meters between
photonsphotons
�� 0.1 second exposure 0.1 second exposure
timetime
Build Up of Interference PatternBuild Up of Interference Pattern
0.5 Seconds 1 Second 5 Seconds
Attenuation = 0.8 * 10-5
Photon Separation = 11.7 m
MachMach--ZehnderZehnder InterferometerInterferometer
Light in different paths have orthogonal polarization
Presence of which path information is controlled by analyzer polarizer
MZ Interferometer PicturesMZ Interferometer Pictures
Analyzer Polarizer at 45°(no which way information)
Analyzer Polarizer at 90°(which way information present)
Fringe VisibilityFringe Visibility
Fringe Visibility =Max - Min
Max + Min
Fringe Visibility ResultsFringe Visibility Results
Lab 3: Lab 3: ConfocalConfocal Microscope Microscope
Imaging of SingleImaging of Single--Emitter Emitter
FluorescenceFluorescence
Lab 4: Lab 4: HanburyHanbury Brown & Brown & TwissTwiss
Setup, Photon Setup, Photon AntibunchingAntibunching
Single Emitters and Photon Single Emitters and Photon
AntibunchingAntibunching
�� Attenuated lasers will sometimes produce Attenuated lasers will sometimes produce
bunches of photons which cannot be avoided.bunches of photons which cannot be avoided.
�� Single photon source requires single emitter that Single photon source requires single emitter that
displays displays antibunchingantibunching..displays displays antibunchingantibunching..
Quantum DotsQuantum Dots
�� Quantum dot Quantum dot -- confines electrons in all confines electrons in all
directionsdirections
�� Colloidal quantum dots Colloidal quantum dots -- nanocrystals dispersed nanocrystals dispersed
through a solutionthrough a solutionthrough a solutionthrough a solution
�� We prepared sample slides of colloidal quantum We prepared sample slides of colloidal quantum
dots through spin coatingdots through spin coating
�� Also used samples prepared by Luke Also used samples prepared by Luke BrisselBrissel
Experimental SetupExperimental Setup
Experimental SetupExperimental Setup
CCD ImagingCCD Imaging
ConfocalConfocal Microscope ScansMicroscope Scans
Scan CloseScan Close--upup
AntibunchingAntibunching HistogramHistogram
Histogram Without Histogram Without AntibunchingAntibunching
We Saw We Saw AntibunchingAntibunching!!
Photonic Bandgap MaterialPhotonic Bandgap Material
�� Photonic Crystals Photonic Crystals --
Spatial periodicity on Spatial periodicity on
order of light order of light
wavelengthwavelength
�� Photonic Bandgap Photonic Bandgap --
No light passes in No light passes in
certain frequency rangecertain frequency range
�� CholestericCholesteric Liquid Crystals Liquid Crystals -- ChiralChiral crystals crystals
that suppress spontaneous emission in stop that suppress spontaneous emission in stop
band and enhance near band edge.band and enhance near band edge.
Scan With Photonic Bandgap Scan With Photonic Bandgap
MaterialMaterial
AntibunchingAntibunching With Photonic With Photonic
Bandgap MaterialBandgap Material
Fluorescence LifetimeFluorescence Lifetime
The EndThe EndThe EndThe End
Questions?Questions?Questions?Questions?
Phase Shift from BBO CrystalsPhase Shift from BBO Crystals
Fringe Visibility ResultsFringe Visibility Results
Delay CharacterizationDelay Characterization
61.81 ns61.81 ns
Spontaneous ParametricSpontaneous Parametric
DownDown--ConversionConversion
SPDC Ring Imaged With CCD SPDC Ring Imaged With CCD
CameraCamera
Single CountsSingle Counts
Horizontal Horizontal WaveplateWaveplate AlignmentAlignment
Vertical Vertical WaveplateWaveplate AlignmentAlignment