What does Quantum Decoherence mean?
Quantum decoherence in physics and quantum computing is the loss of quantum coherence. Quantum coherence is the idea that an individual particle or object has wave functions that can be split into two separate waves.
When the waves operate together in a coherent way, that's referred to as quantum coherence.
Techopedia explains Quantum Decoherence
Quantum decoherence happens when there is no longer a definite phase relation between the two different states. The idea was embarked on in the 1970s, and has been the subject of some quantum research to date. Some describe it as loss of information from a system, while others point out that decoherence “contemplates apparent wave function collapse.”
Like other related quantum concepts, quantum decoherence can have applications to quantum computing systems that are now being conceptualized, if not built, based on a system of ‘qubits’ – items replacing binary bits that can have an array of values either 1, 0 or an undetermined value.
Physicists cite the Schrödinger's cat example as one of the best explanations of how quantum computing works. Quantum decoherence, on the other hand, is a physics principle that has more application to quantum science than quantum computing per se.