Quantum Optics Team A Single Photon Interference By

Quantum Optics Team A: “Single Photon Interference” By: Nicholas Cirucci, Rebecca Pettenski, Christina Loniewski, Timothy Geary, Nathan Damon

Motivation for Lab To show wave-particle duality of photons Quantum: A Guide for the Perplexed, by Jim Al-Khalili

“Interference phenomena are viewed as the most convincing ‘proof’ of the wave nature of light” Introduction to Quantum Optics from Light Quanta to Quantum Teleportation, By Harry Paul

Hypothesis At the single photon level, will the photon exhibit wave-particle duality? Quick overview of experiments

Camera Costs $30, 000 8. 2 x 8. 2 mm image area Internally regulated temperature at -60 degrees Celsius Camera has single-photon detection capability Andor i. Xon DV 887 mode EMCCD Camera (Electron Multiplying Charge Coupling Device) http: //www. optics. rochester. edu/workgroups/lukishova/Quantum. Optics. Lab/homepage/andor_em_ccd_ camera. pdf

Laser Information He. Ne Gas laser 633 nm wavelength (red) No anti-bunching exhibited by this laser Only single, double, and triple photon “groups”

Lab 1 – Mach-Zehnder Interferometer Unpolarizing Beam Splitter Mirror Linear Polarizer Circular Aperture 45 Degree Linear Polarizer Mirror Polarizing Beam Splitter

“Beam Splitting” “The process of splitting becomes conceptually difficult when we think of the beam as consisting of spatially localized energy packets, or photons…what happens to the individual photon when it hits the mirror? Does it split, or does it remain as a whole? ” Introduction to Quantum Optics from Light Quanta to Quantum Teleportation, By Harry Paul Beam splitter

Which-Way Theory At 45 degrees, photon does not know s or p polarization, so there are interference fringes The 45 degree linear polarizer ensures that there is an equal probability that the photon will travel down one arm or the other

Which-Way Theory (cont. ) Quantum mechanical properties are completely dependent upon how they are observed. You cannot accurately measure both the particle and wave properties of light. Quantum Physics: Illusion or Reality? , Alastair I. M. Rae

Sample Calculation Energy of Photon Wavelength = 633 nm Order of Attenuation Laser power = 53. 9 u. W Laser Power—measuring power to make sure both arms of interferometer are the same power—more likely for photon to go where there is more power (if unequal)

Interference on the Single Photon Level? “What happens to the ability of the waves to interfere at very low intensities? Do laser beams interfere after they are strongly attenuated? ” (i. e. on the single photon level) Introduction to Quantum Optics from Light Quanta to Quantum Teleportation, By Harry Paul

Quantum: A Guide for the Perplexed, by Jim Al-Khalili

e Be ssi Quantum: A Guide for the Perplexed, by Jim Al-Khalili

Types of Interference Measurement Changing Polarizer Angles Accumulations Sample picture of Mach-Zehnder Interference Fringes:

Calculation of Fringe Visibility V=(Imax-Imin)/(Imax+Imin) Example of Fringe Intensity Pattern: (Fringe Visibility) V= 0. 658517

Changing Polarizer Angles from 0 -360—Exposure Time of 1 second 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360

Comparison of Maximum and Minimum Fringe Visibility

. 4. 2 0 Fringe Visibility . 6 . 8 Fringe Visibility vs. Changing Polarizer Angles 45 90 135 180 225 Polarizer Angles (degrees) 270 315 360

Accumulations 1 – 10 on the Single Photon Level—Exposure Time. 005 Seconds 1 6 2 7 3 8 4 9 5 10

Comparison of 1 st Accumulation to 10 th Accumulation

Conclusions and Observations from Lab 1 Familiarized with equipment Which-way theory Can only prove wave-particle duality at the single photon level Energy of a photon Attenuation Calculation Using the Andor program in conjunction with the Andor camera Aligned the Mach-Zehnder Interferometer

Lab 2—Young’s Double Slit Experiment 90 um between slits 10 um width of slit

“My theory of light and colours, though it did not occupy a large portion of my time, I conceived to be of more importance than all that I have ever done, or ever shall do besides. ” ~Thomas Young Quantum: A Guide for the Perplexed, by Jim Al-Khalili

Quantum: A Guide for the Perplexed, by Jim Al-Khalili

Spatial Filter Explanation Schematics http: //www. edmundoptics. com/technical-support/lasers/understanding- spatial-filters/ Dirty Profile Clean Profile Lens 2 Lens 1 Laser Beam Pinhole Magnified Beam

Interference Pattern

Sample Picture of Young’s Double Slit Interference Fringes

Fringe Visibility

Accumulations from 2 -20 on the Single Photon Level—Exposure Time. 05 Seconds 11 2 3 4 5 6 7 8 9 10 12 13 14 15 16 17 18 19 20

Fringe Visibility vs. Increasing Accumulations on the Single Photon Level—Exposure Time of. 05 7 Orders of Attenuation Seconds 0. 3 0. 25 Fringe Visibility 0. 2 0. 15 0. 1 0. 05 0 2 3 4 5 6 7 8 9 10 11 12 Accumulations 13 14 15 16 17 18 19 20

Comparison of 2 nd and 20 th Accumulations on Single Photon Level

Conclusions and Observations from Lab 2 Learned much more about interference fringes Interference affected by multiple sources

“Delayed Choice Experiments” Attempting to detect photons after they pass through the slit with a slight delay on the detector After the photon goes through the slit, the detector records which slit it went through after a short period of time If this occurs, then the interference patterns disappear. Quantum: A Guide for the Perplexed, by Jim Al-Khalili Introduction to Quantum Optics from Light Quanta to Quantum Teleportation, By Harry Paul

Sources of Error Calculated 8 orders of attenuation Dust on attenuation filters Misaligned beams Camera noise Software difficulties Dirty Mirrors and/or beam splitters Flea in Camera

$$$ Prices $$$ Attenuation Filter $80 Andor EMCCD Camera $30, 000 Learning about Quantum Optics Priceless

Story of Our Lab “Journey”

Thank You Dr. Lukishova!!! (and Eric )

Bibliography/References 1. http: //www. optics. rochester. edu/workgroups/lukishova/Quantum. Optics. Lab/hom epage/andor_em_ccd_camera. pdf 2. http: //www. edmundoptics. com/technical-support/lasers/understandingspatial-filters/ 3. Quantum: A Guide for the Perplexed, by Jim Al-Khalili 4. Introduction to Quantum Optics from Light Quanta to Quantum Teleportation, By Harry Paul 5. Quantum Physics: Illusion or Reality? , Alastair I. M. Rae