Articles for subject Physics
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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.
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The Mermin-Peres magic square is a neat demonstration of measurement contextuality.
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Projectors are linear operators with the property that the square of the operator is the operator.
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Observables and Projective measurements. The Born rule. Expectation and variance of observables and uncertainty principle.
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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.
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Inner-products and norms are defined. Equipping a vector space with an inner-product gives an inner-product-space, and let’s us define bases.
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Communication through memory-less static channels will be examined, and in particular using repetition codes to counteract the errors introduced by the channel.
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Conditional entropy.
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The joint entropy and its properties
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The relative entropy, or Kullback-Leibler divergence is a measure of the difference of two distributions