StringJunky Posted March 23, 2016 Share Posted March 23, 2016 Can photons pass through glass unperturbed? Can the properties of the photon be altered if they do interact with an atom once re-emitted? Link to comment Share on other sites More sharing options...
swansont Posted March 24, 2016 Share Posted March 24, 2016 Can photons pass through glass unperturbed? Can the properties of the photon be altered if they do interact with an atom once re-emitted? Unperturbed, no. They have to have some interaction slowing them down, but it's a virtual absorption which requires energy and momentum stay the same. All other possibilities interfere and cancel out. If the interaction is real, though, then the properties can change. Link to comment Share on other sites More sharing options...
StringJunky Posted March 24, 2016 Author Share Posted March 24, 2016 Unperturbed, no. They have to have some interaction slowing them down, but it's a virtual absorption which requires energy and momentum stay the same. All other possibilities interfere and cancel out. If the interaction is real, though, then the properties can change. In an interaction, what photon properties can alter? Link to comment Share on other sites More sharing options...
Sensei Posted March 24, 2016 Share Posted March 24, 2016 (edited) In an interaction, what photon properties can alter? Have you heard about polarization by reflection.. ? https://en.wikipedia.org/wiki/Brewster's_angle Very easy to see if you have polarization filter. Point it at f.e. flat water surface, and start spinning polarization filter at hand. Reflection will disappear at right angle of polarization filter. Also while passing through some transparent materials, when there is present external magnetic field, there could happen Faraday polarization rotation. https://en.wikipedia.org/wiki/Faraday_effect https://en.wikipedia.org/wiki/Faraday_rotator Edited March 24, 2016 by Sensei Link to comment Share on other sites More sharing options...
swansont Posted March 24, 2016 Share Posted March 24, 2016 In an interaction, what photon properties can alter? Energy and thus momentum, polarization, direction of propagation. 1 Link to comment Share on other sites More sharing options...
StringJunky Posted March 24, 2016 Author Share Posted March 24, 2016 Energy and thus momentum, polarization, direction of propagation. Thanks. Sorted. Link to comment Share on other sites More sharing options...
imatfaal Posted March 24, 2016 Share Posted March 24, 2016 In an interaction, what photon properties can alter? Number - there are strange materials which will (at certain specific frequencies) taken in one photon and spit out two half energy, opposite polarization photons. This is the process of spontaneous parametric down conversion that is used in quantum eraser experiments - you get two entangled photons with conservation of mom and energy and they have opposite polarizations so that is balanced as well. 1 Link to comment Share on other sites More sharing options...
swansont Posted March 24, 2016 Share Posted March 24, 2016 Number - there are strange materials which will (at certain specific frequencies) taken in one photon and spit out two half energy, opposite polarization photons. This is the process of spontaneous parametric down conversion that is used in quantum eraser experiments - you get two entangled photons with conservation of mom and energy and they have opposite polarizations so that is balanced as well. Good point. You can also just have the photon just disappear, and the energy is dissipated through non-radiative relaxation methods (e.g. increased vibration, i.e. phonons). (Though (pedantically) I'd say that photon number is a system property rather than a photon property) 1 Link to comment Share on other sites More sharing options...
StringJunky Posted March 25, 2016 Author Share Posted March 25, 2016 (edited) Good point. You can also just have the photon just disappear, and the energy is dissipated through non-radiative relaxation methods (e.g. increased vibration, i.e. phonons). (Though (pedantically) I'd say that photon number is a system property rather than a photon property) Is the phonon energy mechanically conducted? If one observed a single atom with a phonon, would it retain that excitation in vacuo permanently? Edited March 25, 2016 by StringJunky Link to comment Share on other sites More sharing options...
swansont Posted March 25, 2016 Share Posted March 25, 2016 Is the phonon energy mechanically conducted? If one observed a single atom with a phonon, would it retain that excitation in vacuo permanently? I'm not a solid state person, but I don't think "single atom" and "phonon" are supposed to appear together. Phonons are, AFAIK, from a collective behavior of a lattice of atoms. Link to comment Share on other sites More sharing options...
StringJunky Posted March 25, 2016 Author Share Posted March 25, 2016 I'm not a solid state person, but I don't think "single atom" and "phonon" are supposed to appear together. Phonons are, AFAIK, from a collective behavior of a lattice of atoms. I suppose that makes sense; an atom is not a lattice and, as you say, a quick gen up on them suggests it's a function of a lattice. Link to comment Share on other sites More sharing options...
swansont Posted March 25, 2016 Share Posted March 25, 2016 I suppose that makes sense; an atom is not a lattice and, as you say, a quick gen up on them suggests it's a function of a lattice. Put another way, a single atom can only translate, it can't vibrate. Link to comment Share on other sites More sharing options...
StringJunky Posted March 25, 2016 Author Share Posted March 25, 2016 Put another way, a single atom can only translate, it can't vibrate. Got you. Cheers. Link to comment Share on other sites More sharing options...
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