quantum optics lab reviejustin justin winkler winkler. lab 1 entanglement and bell’s inequalities....

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