Condensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of constituents in a system is extremely large and the interactions between the constituents are strong. The most familiar examples of condensed phases are solids and liquids, which arise from the electric force between atoms. More exotic condensed phases include the superfluid and the Bose-Einstein condensate found in certain atomic systems at very low temperatures, the superconducting phase exhibited by conduction electrons in certain materials, and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices.

Condensed matter physics is by far the largest field of contemporary physics. By one estimate, one third of all American physicists identify themselves as condensed matter physicists. Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term "condensed matter physics" was apparently coined by Philip Anderson when he renamed his research group - previously "solid-state theory" - in 1967. In 1978, the Division of Solid State Physics at the American Physical Society was renamed as the Division of Condensed Matter Physics.

One of the reasons for calling the field "condensed matter physics" is that many of the concepts and techniques developed for studying solids actually apply to fluid systems. For instance, the conduction electrons in an electrical conductor form a type of quantum fluid with essentially the same properties as fluids made up of atoms. In fact, the phenomenon of superconductivity, in which the electrons condense into a new fluid phase in which they can flow without dissipation, is very closely analogous to the superfluid phase found in helium 3 at low temperatures.

Condensed matter physics is also closely related to the field of materials science.

Topics in condensed matter physics

• Phases
  • Generic phases - Gas; Liquid; Solid
  • Low temperature phases - Bose-Einstein condensate; Fermi gas; Fermi liquid; Fermionic condensate; Luttinger liquid; Superfluid; Supersolid
  • Phase phenomena - Order parameter; Phase transition
• Crystalline solids
  • Types - Insulator; Metal; Semiconductor; Semimetal
  • Electronic properties - Band gap; Bloch wave; Conduction band; Effective mass; Electrical conduction; Electron hole; Valence band
  • Electronic phenomena - Kondo effect; Plasmon; Quantum Hall effect; Superconductivity; Wigner crystal
  • Lattice phenomena - Antiferromagnet; Ferroelectric effect; Ferromagnet; Magnon; Phonon; Spin glass; Topological defect
• Soft matter
  • Types - Amorphous solid; Granular matter; Liquid crystal; Polymer