3,521 research outputs found
Quantum Markov fields on graphs
We introduce generalized quantum Markov states and generalized d-Markov
chains which extend the notion quantum Markov chains on spin systems to that on
-algebras defined by general graphs. As examples of generalized d-Markov
chains, we construct the entangled Markov fields on tree graphs. The concrete
examples of generalized d-Markov chains on Cayley trees are also investigated.Comment: 23 pages, 1 figure. accepted to "Infinite Dimensional Anal. Quantum
Probability & Related Topics
Quantum dynamics of the avian compass
The ability of migratory birds to orient relative to the Earth's magnetic
field is believed to involve a coherent superposition of two spin states of a
radical electron pair. However, the mechanism by which this coherence can be
maintained in the face of strong interactions with the cellular environment has
remained unclear. This Letter addresses the problem of decoherence between two
electron spins due to hyperfine interaction with a bath of spin 1/2 nuclei.
Dynamics of the radical pair density matrix are derived and shown to yield a
simple mechanism for sensing magnetic field orientation. Rates of dephasing and
decoherence are calculated ab initio and found to yield millisecond coherence
times, consistent with behavioral experiments
Spin Readout Techniques of the Nitrogen-Vacancy Center in Diamond
The diamond nitrogen-vacancy (NV) center is a leading platform for quantum
information science due to its optical addressability and room-temperature spin
coherence. However, measurements of the NV center's spin state typically
require averaging over many cycles to overcome noise. Here, we review several
approaches to improve the readout performance and highlight future avenues of
research that could enable single-shot electron-spin readout at room
temperature.Comment: 21 pages, 7 figure
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