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Mixed states for reference frame transformations

delete2026-04-01
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PRE
AI
F
Fiore, Gaetano
F
Fedele Lizzi *
DOI:10.1142/s0219887826502014delete
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Abstract

Abstract

En 中文
In this paper, we discuss the concept of transformations among reference frames (classical or quantum). Usually transformations among classical reference frames have sharply defined parameters; geometrically they can be considered as pure states in the parameters' space, and they form a group. It is however possible that the distributions in the parameters' space are mixed states; such states form a semigroup. Similarly, transformations among quantum reference frames can be either pure or mixed. This gives rise to interesting consequences: the state of a system can be pure with respect to a reference frame and mixed with respect to another; we concretely discuss this in the framework of Galilei transformations in 1+1 dimensions. In particular, if the state of a reference frame with respect to another frame is thermal at some temperature, a quantum particle in the pure (improper) rest state with respect to the first frame will appear in a thermal state with a related nonzero temperature with respect to the other. This can also be discussed in relation to the time/energy uncertainty relation.
Keywords:
Quantum reference frames
mixed transformations
thermal states

Journal

I
International Journal of Geometric Methods in Modern Physics
IF:
2.2
Papers:
258
Citations:
0

Organization

U
University of Naples Federico II
Scholars:
4.7W
Papers: 3.6W
Citations: 51
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