Definition of quasiparticle

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Photonics Dictionary

quasiparticle: A quasiparticle is an emergent phenomenon that occurs in many-body systems, particularly in condensed matter physics, where the collective behavior of a large number of interacting particles can be described as if they were single particles. These quasiparticles are not elementary particles like electrons or protons, but rather effective entities that arise from the interactions within the system.

Emergence: Quasiparticles emerge from the complex interactions of many particles, simplifying the description of these interactions by treating them as single particle-like entities.

Effective properties: Quasiparticles possess effective mass, charge, and other properties that differ from those of the individual particles making up the system. These properties allow them to be treated as if they were real particles in theoretical models.

There are various types of quasiparticles, each corresponding to different physical phenomena.

Phonons: Quasiparticles representing collective vibrations of atoms in a crystal lattice, which can be thought of as quantized sound waves.

Magnons: Quasiparticles associated with collective spin excitations in a magnetic material.

Excitons: Bound states of an electron and a hole (an absence of an electron) in a semiconductor, which can move through the material as a single entity.

Polarons: Quasiparticles consisting of an electron and its associated distortion field in a crystal lattice.

Plasmons: Quasiparticles representing collective oscillations of free electron gas density, often found in metals.

Quasiparticles are crucial for understanding and predicting the behavior of complex systems in condensed matter physics. They provide a powerful framework for explaining phenomena such as superconductivity, superfluidity, and the quantum Hall effect.

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