6,821 research outputs found
Transport of Entanglement Through a Heisenberg-XY Spin Chain
The entanglement dynamics of spin chains is investigated using Heisenberg-XY
spin Hamiltonian dynamics. The various measures of two-qubit entanglement are
calculated analytically in the time-evolved state starting from initial states
with no entanglement and exactly one pair of maximally-entangled qubits. The
localizable entanglement between a pair of qubits at the end of chain captures
the essential features of entanglement transport across the chain, and it
displays the difference between an initial state with no entanglement and an
initial state with one pair of maximally-entangled qubits.Comment: 5 Pages. 3 Figure
Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime
A method to reduce the transit time of majority of carriers in photomixers
and photo detectors to ps is proposed. Enhanced optical fields associated
with surface plasmon polaritons, coupled with velocity overshoot phenomenon
results in net decrease of transit time of carriers. As an example, model
calculations demonstrating (or 2800 and 31.8 W at 1
and 5 THz respectively) improvement in THz power generation efficiency of a
photomixer based on Low Temperature grown GaAs are presented. Due to minimal
dependence on the carrier recombination time, it is anticipated that the
proposed method paves the way for enhancing the speed and efficiency of
photomixers and detectors covering UV to far infrared communications
wavelengths (300 to 1600 nm).Comment: 5 pages, 4 figure
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