Pure and Mixed States
In quantum mechanics, a quantum system is represented by a state vector (or ket) . A quantum system with a state vector is called a pure state. However, it is also possible for a system to be in a statistical ensemble of different state vectors: For example, there may be a 50% probability that the state vector is and a 50% chance that the state vector is . This system would be in a mixed state. The density matrix is especially useful for mixed states, because any state, pure or mixed, can be characterized by a single density matrix.
A mixed state is different from a quantum superposition. In fact, a quantum superposition of pure states is another pure state, for example .
Read more about this topic: Density Matrix
Famous quotes containing the words pure, mixed and/or states:
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—Henry Brooks Adams (1838–1918)
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—Susan B. Anthony (1820–1906)
“That Cabot merely landed on the uninhabitable shore of Labrador gave the English no just title to New England, or to the United States generally, any more than to Patagonia.”
—Henry David Thoreau (1817–1862)