3,346 research outputs found
Bounds on Decoherence and Error
When a confined system interacts with its walls (treated quantum
mechanically), there is an intertwining of degrees of freedom. We show that
this need not lead to entanglement, hence decoherence. It will generally lead
to error. The wave function optimization required to avoid decoherence is also
examined.Comment: 10 pages, plain TeX, no figure
Schulman Replies
This is a reply to a comment of Casati, Chirikov and Zhirov (PRL 85, 896
(2000)) on PRL 83, 5419 (1999).
The suitability of the particlar two-time boundary value problem used in the
earlier PRL is argued
Opposite Thermodynamic Arrows of Time
A model in which two weakly coupled systems maintain opposite running
thermodynamic arrows of time is exhibited. Each experiences its own retarded
electromagnetic interaction and can be seen by the other. The possibility of
opposite-arrow systems at stellar distances is explored and a relation to dark
matter suggested.Comment: To appear in Phys. Rev. Let
Ratcheting up energy by means of measurement
The destruction of quantum coherence can pump energy into a system. For our
examples this is paradoxical since the destroyed correlations are ordinarily
considered negligible. Mathematically the explanation is straightforward and
physically one can identify the degrees of freedom supplying this energy.
Nevertheless, the energy input can be calculated without specific reference to
those degrees of freedom.Comment: To appear in Phys. Rev. Let
Multiple phases in stochastic dynamics: geometry and probabilities
Stochastic dynamics is generated by a matrix of transition probabilities.
Certain eigenvectors of this matrix provide observables, and when these are
plotted in the appropriate multi-dimensional space the phases (in the sense of
phase transitions) of the underlying system become manifest as extremal points.
This geometrical construction, which we call an
\textit{observable-representation of state space}, can allow hierarchical
structure to be observed. It also provides a method for the calculation of the
probability that an initial points ends in one or another asymptotic state
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