Their wavevectors can be placed in Brillouin zones in reciprocal space, and their pseudomomentum is defined up to placement in a Brillouin zone. In a gas of them, their chemical potential is zero, so their thermal type can be created or destroyed by random fluctuations. Quantum mechanically, they can be obtained by adding translational symmetry to the Hamiltonian, and the optical variety can interact with infrared light. However, most of these are of the acoustic variety
Their wavevectors can be placed in Brillouin zones in reciprocal space, and their pseudomomentum is defined up to placement in a Brillouin zone. In a gas of them, their chemical potential is zero, so their thermal type can be created or destroyed by random fluctuations. Quantum mechanically, they can be obtained by adding translational symmetry to the Hamiltonian, and the optical variety can interact with infrared light. However, most of these are of the acoustic variety, and their propagation speed is equal to the speed of sound in a solid. For 10 points, name these quantized vibrational modes in a crystal lattice that notably interact with Cooper pairs in BCS theory.
Their wavevectors can be placed in Brillouin zones in reciprocal space, and their pseudomomentum is defined up to placement in a Brillouin zone.
phonons