Physics:Quantum process: Difference between revisions

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In [[Physics:Quantum mechanics|quantum mechanics]], a '''quantum process''' is a somewhat ambiguous term which usually refers to the time evolution of an ([[Physics:Open quantum system|open]]) quantum system.  Under very general assumptions, a quantum process is described by the [[Physics:Quantum operation|quantum operation]] formalism (also known as a ''quantum dynamical map''), which is a [[Linear map|linear]], trace-preserving, and completely positive map from the set of [[Density matrix|density matrices]] to itself.
In [[Physics:Quantum mechanics|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 [[Physics:Quantum operation|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.
For instance, in quantum process tomography, the unknown quantum process is assumed to be a quantum operation.
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[[File:Quantum_process_concept_map.svg|thumb|280px|process in the Quantum Collection.]]
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[[Category:Quantum mechanics]]
[[Category:Quantum mechanics]]


{{Sourceattribution|Quantum process}}
{{Sourceattribution|Quantum process}}

Latest revision as of 23:35, 23 May 2026


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.

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process in the Quantum Collection.

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. PMID 10057614. Bibcode: 1994PhRvL..73.1060P. 
  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. Bibcode: 2005PhLA..341...48S. 
  • 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. 

Source attribution: Quantum process