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Superposition
Intermediate
A system can be in a combination of states.
A quantum state can be a linear combination of other states: |ψ⟩ = a|0⟩ + b|1⟩, with probabilities |a|² and |b|². Interference arises from the relative phase.
A spin pointing along x is a superposition of up and down.
Not the same as a classical mixture.
In more detail
A quantum state can be a superposition of several basis states, with complex amplitudes. Measurement yields one of the basis outcomes with probabilities given by the squared amplitudes.
Real-world uses
- Quantum computers use superposition to process many possibilities at once.
- Interference effects in experiments rely on superposition.
- Quantum computers use qubits in superposition to explore many computational paths at once.
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Frequently asked questions
Does superposition mean the particle is in two places?
It means the state has amplitudes for each possibility, and interference can occur between them.
Is superposition common?
Yes, it is a generic feature of quantum systems.
Does superposition mean the particle is in two places?
It means the state is a combination of possible outcomes, and measurement gives one of them with a certain probability.
Related topics in Quantum Mechanics
Perturbation theory · Variational principle · Dirac notation · Measurement and collapse · Schrödinger's cat · Entanglement