Kvantumfázisátmenetek

Kvantumfázisátmenetek (Quantum Phase Transitions) are phase transitions that occur at absolute zero temperature, driven by quantum fluctuations rather than thermal fluctuations. Unlike classical phase transitions, which are induced by changes in temperature, quantum phase transitions are triggered by varying a non-thermal parameter, such as pressure, magnetic field, or chemical composition. At these transitions, the system's ground state changes discontinuously or non-analytically.

The critical behavior near a quantum phase transition is characterized by the emergence of quantum criticality. This often involves long-range quantum entanglement and critical fluctuations that persist even at zero temperature. The universality classes of quantum phase transitions are determined by the symmetries of the system and the dimensionality of spacetime. Understanding quantum phase transitions is crucial for comprehending the behavior of many condensed matter systems, including superconductors, magnets, and quantum spin liquids. Experimental probes like specific heat measurements and neutron scattering are used to detect and characterize these phenomena.