Light

https://physics.stackexchange.com/questions/73942/how-do-we-know-photons-have-spin-1

Original 1931 experiment by Raman and Bhagavantam: http://dspace.rri.res.in/bitstream/2289/2123/1/1931%20IJP%20V6%20p353.pdf


Photon spin

Radiation pressure

{tag=Photonics equipment}

= Single photon production and detection experiments
{synonym}

= Single photon
{synonym}

You can't get more direct than this in terms of proving that <photons> exist!

The particular case of the <double-slit experiment> will be discussed at: <single particle double slit experiment>.

Production:
* <spontaneous parametric down-conversion>
* <quantum dot single photon source>
* <video Jeremy O'Brien: "Quantum Technologies" by GoogleTechTalks (2014)> https://www.youtube.com/watch?v=7wCBkAQYBZA&t=531s mentions <optical ring resonators>
* <optical cavities>: https://core.ac.uk/download/pdf/30890926.pdf

Detectors are generally called <photomultipliers>:
* <photomultiplier tube>
* <silicon photomultiplier>
* <superconducting>, mentioned at:
  * https://singlequantum.com/technology/snspd/
  * <video Jeremy O'Brien: "Quantum Technologies" by GoogleTechTalks (2014)> https://youtube.com/watch?v=7wCBkAQYBZA?t=2720

Bibliography:
* https://iopscience.iop.org/book/978-0-7503-3063-3.pdf Quantum Mechanics in the Single Photon Laboratory by Waseem, Ilahi and Anwar (2020)

\Video[https://youtube.com/watch?v=dyXq1u87qew]
{title=How to use an SiPM - Experiment Video by SensLTech (2018)}

\Video[https://www.youtube.com/watch?v=Vt84rSJa7VI]
{title=Single-photon detectors - Krister Shalm by Institute for Quantum Computing (2013)}
{description=
* https://youtu.be/Vt84rSJa7VI?t=721 <Poincaré sphere>
}


Single photon production and detection

{tag=Squeezed coherent state}
{wiki=Squeezed states of light}

A <squeezed coherent state> of <light>.


Squeezed state of light

{tag=Light}
{wiki}

The <science> and engineering of <light>!

When dealing more specifically with individual <photons>, we usually call it <photonics>.


Optics

{tag=Elementary particle}
{wiki}

Initially light was though of as a wave because it experienced interference as shown by experiments such as:
* <double-slit experiment>
* https://en.wikipedia.org/wiki/Newton%27s_rings

But then, some key experiments also start suggesting that <light> is made up of <discrete> packets:
* <Compton scattering>, also suggests that photons carry momentum
* <photoelectric effect>
* <single photon production and detection experiments>
and in the understanding of the 2020 <Standard Model> the photon is one of the <elementary particles>.

This duality is fully described mathematically by <quantum electrodynamics>, where the photon is modelled as a quantized excitation of the photon field.


Ciro Santilli @cirosantilli 37

 Children: Photon