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Is it possible to detect a single phonon? If yes, can it be detected at a well-defined position?
In principle, a phonon should be possible to detect if there is an interaction of the formDadface said:3. The concept of phonons is probably useful but I'm wondering whether they are actually real things and by that I mean whether it is possible, if only in principle, to actually observe them directly.
As far as I can see, this doesn't have much to do with single phonons.Lord Jestocost said:I remember some "listening with a 'quantum ear'": “Local probing of propagating acoustic waves in a gigahertz echo chamber”, Nature Physics 8, 338–343 (2012)
In the abstract they talk about "coherent phonons in SWNT ensembles". I'm not sure what do they mean by that, but it doesn't sound like a single phonon to me.Dadface said:http://www.nature.com/nphys/journal/v2/n8/abs/nphys345.html?foxtrotcallback=true
Is this the sort of thing you're looking for?
Phonons are collective lattice motions with well-defined momenta. Thus individual phonons are localized in reciprocal space, not real space.Demystifier said:Is it possible to detect a single phonon? If yes, can it be detected at a well-defined position?
Phonon (just like photon) does not need to have a well-defined momentum. A superposition of one-phonon states with different momenta is still one phonon.TeethWhitener said:Phonons are collective lattice motions with well-defined momenta.
Almost! In this experiment, they observe an electron that emitted a single phonon. A detection of phonon would correspond to an inverse process in which they observe an electron that absorbed a single phonon.Dadface said:https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.62.1057
I don't know if this is any good.
Theoretically, yes. But I would like to know if something like that has been done in practice.TeethWhitener said:As for detecting a phonon, why isn't Raman scattering acceptable? It involves either creation (Stokes) or annihilation (anti-Stokes) of a phonon via inelastic photon scattering. Theoretically, you could do the experiment with a single photon, though the cross section of Raman scattering is several orders of magnitude smaller than Rayleigh scattering.
Demystifier said:Is it possible to detect a single phonon? If yes, can it be detected at a well-defined position?
I don't see why not. A photon is a quantum of atomic displacement. It is not required that this quantum is in an eigenstate of energy or momentum.Andy Resnick said:(phonons don't have well-defined positions).
This thread is about phonons, not photons.Mech_Engineer said:So-called "photon counting" systems do exist
jtbell said:This thread is about phonons, not photons.
DrDu said:I don't see why not. A photon is a quantum of atomic displacement. It is not required that this quantum is in an eigenstate of energy or momentum.
Yes. I mean, if they aren't eigenstates of energy and crystal momentum, they are time dependent phonons but phonons nevertheless.Andy Resnick said:Phonons are quantized displacements of a crystal (an ordered array of many atoms); a good discussion is in Coleman's "Introduction to Many Body Physics", chapter 2.4.
jtbell said:This thread is about phonons, not photons.
Yes, it is possible to detect single phonons using various experimental techniques such as Raman spectroscopy, Brillouin scattering, and cryogenic detectors.
Detecting single phonons allows us to study the fundamental properties of materials at the quantum level, which can provide valuable insights into their behavior and potential applications.
The sensitivity of the methods used to detect single phonons depends on the experimental setup and the type of detector used. Some techniques, such as cryogenic detectors, are capable of detecting individual phonons with high sensitivity.
Yes, there are some limitations to detecting single phonons, such as the presence of background noise and technical challenges in achieving high enough sensitivity. Additionally, some materials may not exhibit clear signals for single phonon detection.
The ability to detect single phonons has potential applications in fields such as quantum computing, optoelectronics, and materials science. It can also aid in the development of new technologies and materials with unique properties.