Quantum reference frame: Difference between revisions

Revision as of 05:46, 30 June 2011

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{{see also| Frame of reference}}

A '''quantum reference frame''' is a reference frame which is treated quantum theoretically. It, like any [[Frame of reference|reference frame]], is a physical system which defines physical quantities, such as [[time]], position, [[momentum]], [[spin (physics)|spin]], and so on. Because it is treated within the formalism of [[Quantum mechanics|quantum theory]], it has some interesting properties which do not exist in a normal classical reference frame.

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:::<math>n_{max} \simeq \epsilon j^2</math>

So the longevity and the size of the reference frame are of quadratic relation in this particular case.<ref>{{cite journal|last=Bartlett|first=Stephen D.|coauthors=Rudolph, Terry and Spekkens, Robert W.|title=Reference frames, superselection rules, and quantum information|journal=Review of Modern Physics|volume=79|issue=2|month=April–June|pages=555–606|year=2007|doi=10.1103/RevModPhys.79.555 |bibcode=2007RvMP...79..555B}}</ref>

In this spin-<math>j</math> system, the degradation is due to the loss of purity of the reference frame state. On the other hand, degradation can also caused by misalignment of background reference. It has been shown, in such case, the longevity has a linear relation with the size of the reference frame.<ref>{{cite journal| doi = 10.1088/1367-2630/9/5/156| last = Poulin| first = D. |coauthors=J. Yard| title = Dynamics of a quantum reference frame|year=2007|journal=New J. Phys|volume = 9| issue = 5|pages=156}}</ref>