Photon Quantum Mechanics
This is a project funded by the National Science Foundation to establish a set of undergraduate laboratories to study the fundamentals of quantum mechanics. The experiments are laboratory exercises on topics of quantum mechanics that are otherwise theoretical, abstract or even unintuitive. The central issue of the experiments is quantum superposition: the ability of a quantum to be in two places at the same time or to be in to be in a correlated superposition of states with other quanta. Our original ideas were published in the American Journal of Physics [C.H. Holbrow, E.J. Galvez and M.E. Parks, "Photon Quantum Mechanics and beam splitters," Am. J. Phys. 70, 260-265 (2002) Reprint].
Simplicity and cost are primary concerns. An article describing these experiments has been published: “Interference with correlated photons: Five quantum mechanics experiments for undergraduates,” E. J. Galvez, C. H. Holbrow, M. J. Pysher, J. W. Martin, N. Courtemanche, L. Heilig, and J. Spencer, Am. J. of Phys. 73, 127-140 (2005) Reprint [Erratum: in Eq. 13, k0 in the Dirac delta should be multiplied by 2 (thanks to J.-T. Shen); page 139, 1st column, before-last line: should read ne = 1.561 instead of ne = 1.542--the latter is the extraordinary index of refraction at 915.8 nm.]. Some of the equipment details in this publication are a bit dated. See below for more recent equipment options.
A general article on this project appeared as a book chapter: “Undergraduate Laboratories Using Correlated Photons: Experiments on the Fundamentals of Quantum Physics,” E.J.Galvez, in Invention and Impact: Building Excellence in Undergraduate Science, Technology, Engineering and Mathematics (STEM) Education, (AAAS, 2004) pp 113-118. Reprint.
We have taught "Introduction to Quantum Mechanics" (Phys434) with a lab since 2005. A description of the quantum mechanics algebra used with these labs in appeared in the May 2010 issue of the American Journal of Physics: "Qubit Quantum Mechanics with Correlated Photon Experiments," E.J. Galvez, American Journal of Physics 78 510-519 (2010). Reprint
A recent 2014 review article on the photon experiments lists all previous efforts, including citations to the original articles that inspired the experiments plus useful discussions: "Resource Letter SPE-1: Single-Photon Experiments in the Undergraduate Laboratory," Enrique J. Galvez, American Journal of Physics 82, 1018-1028 (2014). Reprint
Video of Physics and Astronomy Colloquium (~1 hr) given by Kiko Galvez at Stony Brook University in 2009 "Quantum Interference of Light: From Fundamentals to Qubits." Video Courtesy: Peter M. Koch.
Video by Scientific American on quantum entanglement.
How-to
VIDEOS
These are two detailed video
tutorials about setting up the apparatus for photon experiments from scratch.
These were made on January 2013 by Kiko Galvez. Video production credits: Sam
Ward. Our hope is that they will help with the basic alignments that are needed
for setting up the experiments. There are two videos:
1- How set up a
down-conversion experiment (58 min): link
2- How to set up a single-photon interference experiment. It assumes
down-conversion is already working (42 min):
link
Downloads:
-- Lab Manual: comprehensive
step-by-step instructions for setting up the labs. Note: this manual is in the
process of being updated.
-- PDF of Mathcad worksheet for calculating the
phase-matching angle for type-I parametric down-conversion with BBO crystal.
-- Labview files for doing experiments:
---
Dynamical phase: records photon
counts as voltage sent to piezo is stepwise increased.
---
Geometrical Phase:
records photon counts pausing after every point--for manually changing a
parameter, such as the orientation of a wave-plate or polarizer.
--- MDyn2015Arduino16 is a labview
program that runs arduino. (Contact us for more information on vi's needed.
--NEW 2018: Photon data acquisition
programs with Matlab GUIs (written by Behzad Khajavi) using Altera coincidence
board:
---
ContinuousCounting (free running
program for 2 detectors).
--- ContinuousCountingPiezo_Altera
(free running program for interference experiments that allows manual setting of
piezo-electric voltage using Arduino circuit -see below).
--- PiezoScan_2Detectors_Altera
(program that scans the piezo-electric voltage for interference experiments).
--- Tomography_Manual_Altera (program
that takes a set of specified number of measurements pausing in between
measurements for setting of optical elements such as waveplates or polarizers
for doing tomography or Bell tests).
--- Paused_3Detectors_Altera (program
for 3 detectors with specified set of measurements with pause for changing
component settings, useful for experiments such as photon Stern Gerlachs or
Hanbury-Brown-Twiss test).
--- PiezoScan_3Detectors_Altera
(program that scans the piezo for interference experiments with 3 detectors).
--- QKD_4Detectors_Altera (program that
performs a specified set of measurements for use with 4 detectors).
Check also Mark Beck's website (Whitman College) for more information and downloads on similar types of experiments.
2018 Updates
Apologies that the links have not been working for a while. Now they do! First, the good news: prices have gone down by a lot! Below are documents with the most recent summaries of prices:
If you are stuck! Here are some ideas (2017): link.
Arduino found a way... A much deserved update for interference experiments: using low-cost Arduino-based circuit to scan the voltage applied to a piezo-electric:
General
The source of single photons involves the use of photon pairs produced by spontaneous parametric down conversion. The pairs are detected in coincidence. Below we describe our more recent results of implementations of experiments in our curriculum.
Photon Quantum Mechanics for first-year students (taught in our intro course Phys131):
A lab on the quantum eraser. and results taken by students.
2018 version of a Lab for a Quantum Mechanics Course (NEW!)
Lab 1 Alignment and parametric down conversion:
Lab 3 Single-photon interference:
Lab 4 Quantum Eraser:
Lab 6 Entanglement
The apparatus:
Research Experiments (which were parts of capstone undergraduate projects):
We could not help ourselves but to ask a few questions about a few topics:
The Entangled Quantum Eraser. This is an experiment with entangled photons where the labeling of paths of photons going through an interferometer is done by entangled partners in a remote location. "Nonlocal Labeling of Paths in a Single-Photon Interferometer," M.J. Pysher,* E.J. Galvez, K. Misra,* K.R. Wilson,* B.C. Melius,* and M. Malik* Physical Review A 72, 052327 (2005). Reprint.
Remote interferometer. This is a really cool experiment. Correlations between entangled photons are manipulated in such a way that the phase of the interference pattern of photons going through an interferometer is changed by actions on entangled photons that do not go through the interferometer. "Phase Shifting of an Interferometer using Nonlocal Quantum-State Correlations," E.J. Galvez, M. Malik,* and B.C. Melius,* Physical Review A-Rapid Communications 75, 020302(R) (2007). Reprint
Bell inequalities on single photons entangled in space and polarization: "Bell-Inequality Violations with Single Photons Entangled in Momentum and Polarization," B.R. Gadway, E.J. Galvez, and F. De Zela, Journal of Physics B 42, 015503 1-9 (2009). PDF This paper was selected as one of the highlight papers of the journal in 2009! Byrce Gadway was also the recipient of the 2008 Apker Award of the American Physical Society for this work.
More recently we have been looking at the spatial modes of single photons: "Imaging Spatial-Helical Mode Interference of Single Photons," E.J. Galvez, E. Johnson, B.J. Reschovsky, L.E. Coyle, and A. Shah, Proceedings of SPIE 7613 (2010). PDF
The results of our efforts to measure the helical mode of single photons appeared published in May 2010: "InterferometricMeasurementofthe Helical Mode of a Single Photon," E.J. Galvez, L.E. Coyle, E. Johnson, and B.J. Reschovsky, New Journal of Physics 13, 053017 1-10 (2011). Link
My colleagues from the Universidad Nacional Autonoma de Mexico made this beautiful experiment setting up the Hong-Ou-Mandel interferometer: "The Hong-Ou-Mandel interferometer in the undergraduate laboratory," J. Carivioto-Lagos, G. Armendariz P., V. Velazquez, E. Lopez-Moreno, M. Grether, and E.J. Galvez, European Journal of Physics 33, 1843 (2012). link
