One Photon In, TWO Photons Out

A fascinating phenomenon with a forbidding name (parametric down conversion) occurs in certain crystals. A single photon enters, but two emerge. There are myriad pair combinations; but in each case, the sum of the total energy and momentum of the two output photons exactly equals those of the single input photon.

Parametric down conversion is finding a host of uses in physics, from testing the efficiency of high-tech single-photon detectors to cutting-edge experiments in quantum mechanics.

Alan Migdall of the National Institute of Standards and Technology explains and demonstrates how it's done.

Category:

Science & Technology

Tags:

• parametric
• down conversion
• quantum
• NIST
• Standards and Technology
• photon detector
• nonlinear
• crystal
• Migdall
• JQI
• Joint Quantum Institute

[craigmancool]

what type of energy are you measuring?

How can you say the momentum and energy are exactly equal when the mass is double and therefore kinetic yield is higher withing the total experiment..

[craigmancool]

what type of energy are you measuring?

[heloizyjhenifer]

Now *this* is a science video, to hell with thenewscientist and their gadgets.

Thanks for the upload, this is quality.

[bobhwantstoknow]

Is there a relatively cheap or common substance that can produce parametric down conversion? I've heard of beta barium borate, but it's a bit expensive. I'm looking for something that can demonstrate the principle, it doesn't have to be very high quality. Thanks.

[bobhwantstoknow]

@nickharvey7

You can only collapse the wave form once and "produce" one particle. If you set up many detectors only one of them will detect the particle.

[RevDevilin]

The jazz at the end was the icing on the cake, marvellously made vid, more more pls

My mind wandered to entanglement possible application ?

[nickharvey7]

Interesting video! Is the photon a wave until it comes in contact with a detector? I was thinking that the more detectors you set up the more places you will collapse the wave function. Therefore the more photons you will create or form.