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seen Oct 17 '13 at 3:46

May
31
awarded  Yearling
May
31
awarded  Yearling
Mar
18
comment Seeing a mirage through mirror?
@JackMoody Didn't you mean to say instead : "If you were to use say a camera or video-camera, then the results would NOT be dramatically different"
Mar
8
comment Scaling of quantum error correction
Thanks for your answer. So if I understand correctly, the qubit space is not a relevant parameter, just the number of gates is ?
Mar
8
awarded  Scholar
Mar
8
accepted Scaling of quantum error correction
Mar
7
awarded  Commentator
Mar
7
comment Can light waves cause beats?
@Cheeku I'm not sure what you mean by "not the same procedure". It is the same physical effect, it is just that it is difficult (but not impossible) to make two independent sources interfere.
Mar
7
awarded  Student
Mar
7
asked Scaling of quantum error correction
Mar
7
comment Can light waves cause beats?
+1 The key point is that most of the light around us is from incoherent sources. The easiest way to obtain beats is to start from a single source (a laser for instance), split it in two, shift the frequency of one the beams (using an acousto-optic modulator for instance) and have them interfere again. The signal generated by a photodiode will exhib a beat.
Feb
28
comment What is a two-photon process?
2) This statement is correct.
Feb
28
comment What is a two-photon process?
1) You need a non linear effect, which is usually week. Since the efficiency of second harmonic generation increases with the power, high power allows the effect to produce bright beams. Note that the efficiency of the opposite effect (creation of pairs of photons) doesn't increase with higher power of the pump beam, so you usually just create pairs of photons and not a bright two-color beam. See en.wikipedia.org/wiki/Parametric_down_conversion. You can then put your crystal between mirrors to form a en.wikipedia.org/wiki/Optical_parametric_oscillator
Feb
27
comment What is a two-photon process?
Classical physics goes a long way to explain the concept of second harmonic generation in a nonlinear crystal. It is just one two-photon process. Other effects cannot be introduced that easily and need a full quantum treatment from the start.
Feb
27
revised What is a two-photon process?
added 1 characters in body
Feb
27
revised What is a two-photon process?
added 2 characters in body
Feb
27
awarded  Critic
Feb
27
revised What is a two-photon process?
added 1 characters in body
Feb
27
answered What is a two-photon process?
Feb
22
answered Optical refocusing efficiency