I have a book on quantum computation that explains the concept of a mixed quantum state. The definition is pretty plain, you just have a boring probability distribution over a set of quantum states.(adsbygoogle = window.adsbygoogle || []).push({});

What I would like to know is why we need mixed states. How are they represented physically in nature. What kind of leverage do they give us over pure states in describing an experiment? What kinds of homework problems would you expect to solve using them ;-)

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# What is a Mixed State?

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