decoherence

Decoherence is the process by which a quantum system loses its quantum properties through interaction with its environment.

When particles that exist in superposition—multiple states simultaneously—interact with surrounding matter, they "collapse" into definite classical states.

Decoherence explains why quantum effects like superposition appear at atomic scales but not in everyday objects: The experiment failed because decoherence destroyed the entanglement before measurements could be taken.

The concept is central to quantum computing, where maintaining coherence long enough to perform calculations remains a major engineering challenge.