159 research outputs found
Loss-resistant state teleportation and entanglement swapping using a quantum-dot spin in an optical microcavity
We present a scheme for efficient state teleportation and entanglement
swapping using a single quantum-dot spin in an optical microcavity based on
giant circular birefringence. State teleportation or entanglement swapping is
heralded by the sequential detection of two photons, and is finished after the
spin measurement. The spin-cavity unit works as a complete Bell-state analyzer
with a built-in spin memory allowing loss-resistant repeater operation. This
device can work in both the weak coupling and the strong coupling regime, but
high efficiencies and high fidelities are only achievable when the side leakage
and cavity loss is low. We assess the feasibility of this device, and show it
can be implemented with current technology. We also propose a spin manipulation
method using single photons, which could be used to preserve the spin coherence
via spin echo techniques.Comment: The manuscript is extended, including BSA fidelity, efficiency, and a
compatible scheme for spin manipulations and spin echoes to prolong the spin
coherenc
Adaptation Framework and Strategy Part 3: an adaptation strategy for agriculture in Ningxia, Northwest China
The Impacts of Climate Change on Chinese Agriculture - Phase II National Level Study final report
Experimental Quantum Teleportation with a 3-Bell-state Analyzer
We present a Bell-state analyzer for time-bin qubits allowing the detection
of three out of four Bell-states with linear optics, two detectors and no
auxiliary photons. The theoretical success rate of this scheme is 50%. A
teleportation experiment was performed to demonstrate its functionality. We
also present a teleportation experiment with a Fidelity larger than the cloning
limit of F=5/6.Comment: 11 pages, 14 figure
Conditional beam splitting attack on quantum key distribution
We present a novel attack on quantum key distribution based on the idea of
adaptive absorption [calsam01]. The conditional beam splitting attack is shown
to be much more efficient than the conventional beam spitting attack, achieving
a performance similar to the, powerful but currently unfeasible, photon number
splitting attack. The implementation of the conditional beam splitting attack,
based solely on linear optical elements, is well within reach of current
technology.Comment: Submitted to Phys. Rev.
Optical Bell-state analysis in the coincidence basis
Many quantum information protocols require a Bell-state measurement of
entangled systems. Most optical Bell-state measurements utilize two-photon
interference at a beam splitter. By creating polarization-entangled photons
with spontaneous parametric down-conversion using a first-order
Hermite-Gaussian pump beam, we invert the usual interference behavior and
perform an incomplete Bell-state measurement in the coincidence basis. We
discuss the possibility of a complete Bell-state measurement in the coincidence
basis using hyperentangled states [Phys. Rev. A, \textbf{58}, R2623 (1998)].Comment: 5 pages, 5 figure
The anomalous behavior of coefficient of normal restitution in the oblique impact
The coefficient of normal restitution in an oblique impact is theoretically
studied. Using a two-dimensional lattice models for an elastic disk and an
elastic wall, we demonstrate that the coefficient of normal restitution can
exceed one and has a peak against the incident angle in our simulation.
Finally, we explain these phenomena based upon the phenomenological theory of
elasticity.Comment: 4 pages, 4 figures, to be appeared in PR
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