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    Quantum process

    From Handwiki - Reading time: 1 min

    Short description: Time evolution of quantum systems

    In quantum mechanics, a quantum process is a somewhat ambiguous term which usually refers to the time evolution of an (open) quantum system. Under very general assumptions, a quantum process is described by the quantum operation formalism (also known as a quantum dynamical map), which is a linear, trace-preserving, and completely positive map from the set of density matrices to itself.

    For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.

    However, not all quantum processes can be captured within the quantum operation formalism;[1][2] in principle, the density matrix of a quantum system can undergo completely arbitrary time evolution.

    References

    1. Pechukas, Philip (1994). "Reduced Dynamics Need Not Be Completely Positive". Physical Review Letters 73 (8): 1060–1062. doi:10.1103/PhysRevLett.73.1060. ISSN 0031-9007. 
    2. Shaji, Anil; Sudarshan, E.C.G. (2005). "Who's afraid of not completely positive maps?". Physics Letters A (Elsevier BV) 341 (1-4): 48–54. doi:10.1016/j.physleta.2005.04.029. ISSN 0375-9601. 
    • Nielsen, Michael A.; Chuang, Isaac L. (2010). Quantum Computation and Quantum Information (2nd ed.). Cambridge: Cambridge University Press. ISBN 978-1-107-00217-3. OCLC 844974180. 




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