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Decoherence
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Interaction with environment destroys superposition.
Interaction with the environment rapidly destroys phase relations between components of a superposition, making a system look classical. It explains the disappearance of quantum interference for large objects.
A dust grain decoheres in 10⁻³¹ s in air.
Doesn't solve the measurement problem by itself.
In more detail
Decoherence is the loss of quantum coherence due to interaction with the environment, which makes superpositions appear classical. It explains why macroscopic objects do not show quantum effects.
Real-world uses
- Quantum computers must control decoherence to keep qubits working.
- Decoherence explains the transition from quantum to classical behaviour.
- Quantum computer builders study decoherence, since interaction with the environment destroys the superpositions their machines need.
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Frequently asked questions
Does decoherence collapse the wavefunction?
It does not collapse it, but it spreads quantum information into the environment.
How do we avoid it?
Cooling systems, isolating them and using error correction.
How does decoherence explain the classical world?
Interaction with the environment makes superpositions effectively unobservable, so large objects look classical.
Related topics in Quantum Mechanics
Entanglement · Bell's inequalities · EPR paradox · Interpretations of QM · Quantum computing: qubits · Quantum gates