1,154 research outputs found
Almost perfect state transfer in quantum spin chains
The natural notion of almost perfect state transfer (APST) is examined. It is
applied to the modelling of efficient quantum wires with the help of spin
chains. It is shown that APST occurs in mirror-symmetric systems, when the
1-excitation energies of the chains are linearly independent over rational
numbers. This result is obtained as a corollary of the Kronecker theorem in
Diophantine approximation. APST happens under much less restrictive conditions
than perfect state transfer (PST) and moreover accommodates the unavoidable
imperfections. Some examples are discussed.Comment: 11 page
Robustness of spin-chain state-transfer schemes
This is a shortened and slightly edited version of a chapter in the
collection "Quantum State Transfer and Network Engineering", edited by G.M.
Nikolopoulos and I. Jex, where we review our own research about the robustness
of spin-chain state-transfer schemes along with other approaches to the topic.
Since our own research is documented elsewhere to a large extent we here
restrict ourselves to a review of other approaches which might be useful to
other researchers in the field
The effective temperature
This review presents the effective temperature notion as defined from the
deviations from the equilibrium fluctuation-dissipation theorem in out of
equilibrium systems with slow dynamics. The thermodynamic meaning of this
quantity is discussed in detail. Analytic, numeric and experimental
measurements are surveyed. Open issues are mentioned.Comment: 58 page
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