In this article, we are going to discuss what phonon and photon are, their similarities, their definitions, applications of phonon and photon and finally the difference between photon and phonon.
Photon is a topic discussed in wave mechanics. In the quantum theory, it is observed that waves also have particle properties. The quantum theory of light suggests that light travels in bundles of waves. Each of these wave packets behaves as a particle. The photon is the particle of the wave. It is a fixed amount of energy depending only on the frequency of the wave. Photons are considered as packets of energy. With the development of relativity, it was discovered that waves also have a mass.
This is because waves behave as particles on interactions with matter. However, the rest mass of a photon is zero. They are both gas of bosons. Phonons have polarization, transverse and longitudinal while for photons is only transverse. They can have a mass, depending on the system.
It's also possible to define a pseudo momentum. An interesting thing, in my opinion, is phononic crystal. This is an analogy from photonic crystal. Phononic crystals are metamaterials which can be used to manipulate phonons, like trapping or changing the band gap for phonons in a way to amplifying or suppressing sound waves below or above certain cutoff frequencies. Changing the properties of the material like bulk modulus, density or others, it's possible to make the acoustic refractive index periodic, like in photonic crystal where the refractive index is periodic.
This implies a modification of the speed of the waves in the two cases. Finally, I want to express a thought. Even if phonons don't belong to the Standard Model, this doesn't imply that are not real. Even the definition of photon sometimes can be misleading, see other questions here, or in the literature. After all, these are descriptions of what we observe, and if we can measure something, then it's real.
Phonons are quantum states of the harmonic oscillator formed by a material lattice, for example a salt crystal. Photons are quantum states of postulated harmonic oscillators that as far as we know have no material origin. If they had we might call that the aether.
So the have a lot in common but not everything. I would like to add a few interesting facts that I believe are not mentioned in the other answers and are important. As well as photons, phonons can interact via parametric down conversion[17] and form squeezed coherent states. In this active medium, a stimulated emission of phonons leads to amplification of the sound waves, resulting in a sound beam coming out of the device.
The sound wave beams emitted from such devices are highly coherent. Recent research has shown that phonons and rotons may have a non-negligible mass and be affected by gravity just as standard particles are.
Because the part of a material pointing towards a gravitational source is closer to the object, it becomes denser on that end. From this, it is predicted that phonons would deflect away as it detects the difference in densities, exhibiting the qualities of a negative gravitational field.
This is a very interesting point, because based on this even quasiparticles can bend spacetime, since they do possess stress-energy. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How similar are phonons and photons? Ask Question. Asked 7 months ago.
Active 7 months ago. Viewed 2k times. A phonon is a discrete quantum of vibration. So this text seems to put the two particles on equal footing in some way. Improve this question. Alexander 2 2 silver badges 10 10 bronze badges.
Figure1: Normal modes of vibration progression through a crystal. The amplitude of the motion has been exaggerated for ease of viewing; in an actual crystal, it is typically much smaller than the lattice spacing. In the similar way that photons are particles of light, phonons are particles of sound or heat. Basically, they are quantized energy, which shows wave-like and particle-like properties simultaneously.
Vibrating atoms or molecules around their lattices causes the phenomenon. At low frequency, phonons of sound are produced. In other hand, high frequency vibration of atoms and molecules generate phonons of heat. In the case of photons, transition between different energy levels of electrons emits photons. The vibration of atoms and molecules produce phonons. Photons particles that carry light and electromagnetic do not interact with each other if they have different wavelength.
However, phonons at different frequencies can mix together and generate superimposed wavelength. Therefore, there is high chance that phonon amplification by stimulated emission of radiation applications are almost the same as applications from laser.
The only difference is that photon laser is at higher frequency and higher energy compared with phonon laser. We can use analogous derivation to build a model about phonon laser. Similarity and difference are derived from current knowledge as well. However, reality check, the limitations and current development updates of phonon laser are required for better knowledge.
0コメント