Quantum mechanics
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Quantum entanglement
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Particle physics
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Measurement in quantum mechanics
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Mechanics
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Quantum information science
Statistical mechanics
Functional analysis
Quantum state
John von Neumann
Square root of a matrix
Density matrix
A density matrix is a matrix that describes a quantum system in a mixed state, a statistical ensemble of several quantum states. This should be contrasted with a single state vector that describes a q...
Density matrix - Wikipedia
Density matrix - Wikipedia