Macroscopic quantum state

A macroscopic quantum state is a state of matter in which macroscopic properties, such as mechanical motion,^[1] thermal conductivity, electrical conductivity^[2] and viscosity, can be described only by quantum mechanics rather than merely classical mechanics.^[3] This occurs primarily at low temperatures where little thermal motion is present to mask the quantum nature of a substance.

Macroscopic quantum phenomena can emerge from coherent states of superfluids and superconductors.^[3] Quantum states of motion have been directly observed in a macroscopic mechanical resonator (see quantum machine).