Quantum dynamics of tight-binding networks coherently controlled by external fields |
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Authors: | Yang Shuo Song Zhi and Sun Chang-pu |
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Institution: | (1) Department of Physics, Nankai University, Tianjin, 300071, China;(2) Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100080, China |
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Abstract: | With some reviews on the investigations on the schemes for quantum state transfer based on spin systems, we discuss the quantum
dynamics of magnetically-controlled networks for Bloch electrons. The networks are constructed by connecting several tight-binding
chains with uniform nearest-neighbor hopping integrals. The external magnetic field and the connecting hopping integrals can
be used to control the intrinsic properties of the networks. For several typical networks, rigorous results are shown for
some specific values of external magnetic field and the connecting hopping integrals: a complicated network can be reduced
into a virtual network, which is a direct sum of some independent chains with uniform nearest-neighbor hopping integrals.
These reductions are due to the fermionic statistics and the Aharonov-Bohm effects. In application, we study the quantum dynamics
of wave packet motion of Bloch electrons in such networks. For various geometrical configurations, these networks can function
as some optical devices, such as beam splitters, switches and interferometers. When the Bloch electrons as Gaussian wave packets
input these devices, various quantum coherence phenomena can be observed, e.g., the perfect quantum state transfer without
reflection in a Y-shaped beam, the multi-mode entanglers of electron wave by star-shaped network, magnetically controlled
switches, and Bloch electron interferometer with the lattice Aharonov-Bohm effects. With these quantum coherent features,
the networks are expected to be used as quantum information processors for the fermion system based on the possible engineered
solid state systems, such as the array of quantum dots that can be implemented experimentally.
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Keywords: | quantum information quantum state transfer entanglement A-B effect |
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