Comparison of Several Physical Properties of Phonons and Photons

Phonon Photon
Type of boson
type-II composite
simple
Propagating media
discrete
continuous
Interactive?
yes
yes in nonlinear media, no in linear media
Massive?
yes
no
Macroscopic description
wave equations for elastic continuum 
Maxwell equations
Microscopic description
Schrödinger equation
Quantum Electrodynamics
Number of normal modes per allowed k
3p modes for each k
2 modes for each k
Dispersive?
always: w = ws(k)
not in vacuum: w = ck
Restriction on wave vector k
confined to first Brillouin zone
arbitrary
Linear momentum?
vanishes
non-zero
Spin
not defined
s = 1

Table Source:
X. Hu, Quantum Fluctuations In Condensed Matter Systems, UM Ph.D. thesis 1997, Page 31.
X. Hu and F. Nori, UM Preprint, 1995.
Physica B 263, 16 (1999); This summarizes one of the two Plenary Talks at the
Ninth International Conference on Phonon Scattering in Condensed Matter, Lancaster, 1998.

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