What is difference between phonon and photon
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Photons and phonons are both bosonic particles, the former representing a quanta of light and the latter a quanta of atomic lattice vibration. Both are not conserved, and can be destroyed or created in a number of physical processes. In general, they are very good analogs of one another and I often circle back to photons when introducing phonons in a solid state physics course. However, there are some differences:
phonons exist only in systems with atoms to vibrate (crystalline solids are the simplest case). This means they are not ‘elementary particles’, and it also means that their momentum is only uniquely defined in the first Brillouin zone
photons in free space have one type of dispersion relation (energy and momentum are always proportional), while phonons in crystalline solids (for example) typically show two types of dispersions (optical and acoustic) and multiple branches of each type (depending how many atoms are in a unit cell and dimensionality). The dispersion relation determines both ‘how fast a particle moves’ and how the number of particles increases with temperature
in a easy way✌✌✌Max Planck , a German Physicist first used the idea of quantization of energy which in simple words can be understood as the minimum possible energy that can be absorbed or emitted in discrete or discontinuous manner. He proposed that energy was emitted or absorbed in the form of energy packets which he called “photons” for light energy and “phonons” for heat energy.
In case of light energy , the energy of each photon can be calculated by
E = h * f
where E is the energy of a single photon
h is the planck’s constant having value 6.626 * 10e-34 J sec
and f is the frequency of the radiation of whose photon is a part.
Thanks for reading !
phonons exist only in systems with atoms to vibrate (crystalline solids are the simplest case). This means they are not ‘elementary particles’, and it also means that their momentum is only uniquely defined in the first Brillouin zone
photons in free space have one type of dispersion relation (energy and momentum are always proportional), while phonons in crystalline solids (for example) typically show two types of dispersions (optical and acoustic) and multiple branches of each type (depending how many atoms are in a unit cell and dimensionality). The dispersion relation determines both ‘how fast a particle moves’ and how the number of particles increases with temperature
in a easy way✌✌✌Max Planck , a German Physicist first used the idea of quantization of energy which in simple words can be understood as the minimum possible energy that can be absorbed or emitted in discrete or discontinuous manner. He proposed that energy was emitted or absorbed in the form of energy packets which he called “photons” for light energy and “phonons” for heat energy.
In case of light energy , the energy of each photon can be calculated by
E = h * f
where E is the energy of a single photon
h is the planck’s constant having value 6.626 * 10e-34 J sec
and f is the frequency of the radiation of whose photon is a part.
Thanks for reading !
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