Articles for subject Quantum
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The description of physical states as vectors in a Hilbert space can be extended to a probabilistic description when we don’t have complete information. It turns out we are forced to use such a description in certain situations.

The MerminPeres magic square is a neat demonstration of measurement contextuality.

Projectors are linear operators with the property that the square of the operator is the operator.

Observables and Projective measurements. The Born rule. Expectation and variance of observables and uncertainty principle.

Quantum mechanics can be encapsulated by a set of postulates. In this set we will take the Hilbert space \(\mathcal{H}\) as the primary object.

Innerproducts and norms are defined. Equipping a vector space with an innerproduct gives an innerproductspace, and let’s us define bases.

The Dirac braket notation is popular in Quantum Mechanics but at its core this is just an elegant notation for vectors of complex numbers. It’s introduced in a finite dimensional complex vector space.

For some example noisy 1qubit channels we give their representation in terms of Kraus Operators, the dynamical matrix and the process matrix.