29,461 research outputs found
Three-body interactions on a triangular lattice
We analyze the hard-core Bose-Hubbard model with both the three-body and
nearest neighbor repulsions on the triangular lattice. The phase diagram is
achieved by means of the semi-classical approximation and the quantum Monte
Carlo simulation. For a system with only the three-body interactions, both the
supersolid phase and one third solid disappear while the two thirds solid
stably exists. As the thermal behavior of the bosons with nearest neighbor
repulsion, the solid and the superfluid undergo the 3-state Potts and the
Kosterlitz-Thouless type phase transitions, respectively. In a system with both
the frustrated nearest neighbor two-body and three-body interactions, the
supersolid and one third solid revive. By tuning the strength of the three-body
interactions, the phase diagram is distorted, because the one-third solid and
the supersolid are suppressed.Comment: 6 pages, 11 figure
Effect of weak measurement on entanglement distribution over noisy channels
Being able to implement effective entanglement distribution in noisy
environments is a key step towards practical quantum communication, and
long-term efforts have been made on the development of it. Recently, it has
been found that the null-result weak measurement (NRWM) can be used to enhance
probabilistically the entanglement of a single copy of amplitude-damped
entangled state. This paper investigates remote distributions of bipartite and
multipartite entangled states in the amplitudedamping environment by combining
NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has
no positive effect on the distribution of bipartite maximally entangled states
and multipartite Greenberger-Horne-Zeilinger states, although it is able to
increase the amount of entanglement of each source state (noisy entangled
state) of EDPs with a certain probability. However, we find that the NRWM would
contribute to remote distributions of multipartite W states. We demonstrate
that the NRWM can not only reduce the fidelity thresholds for distillability of
decohered W states, but also raise the distillation efficiencies of W states.
Our results suggest a new idea for quantifying the ability of a local filtering
operation in protecting entanglement from decoherence.Comment: 15 pages, 9 figures. Minor revision has been mad
The Realization and Dectection of Weyl Semimetals and Chiral Anomaly in Cold Atomic Systems
In this work, we describe a method to realize 3D Weyl semimetal by coupling
multilayers of honeycomb optical lattice in the presence of a pair of Raman
lasers. The Raman lasers render each isolated honeycomb layer a Chern
insulator. With finite interlayer coupling, the bulk gap of the system closes
at certain out-of-plane momenta due to Raman assisted tunnelling and result in
the Weyl semimetal phase. Using experimentally relevant parameters, we show
that both one and two pairs of Weyl points can be realized by tuning the
interlayer coupling strength. We suggest that Landau-Zener tunnelling can be
used to detect Weyl points and show that the transition probability increases
dramatically when Weyl point emerges. The realization of chiral anomaly by
using a magnetic field gradient is also discussed.Comment: 6 pages, 5 figures. Comments are welcom
A new potential radiosensitizer: ammonium persulfate modified WCNTs
Radiotherapy plays a very important role in cancer treatment. Radiosensitizers have been widely used to enhance the radiosensitivity of cancer cells at given radiations. Here we fabricate multi-walled carbon nanotubes with ammonium persulfate, and get very short samples with 30-50 nanometer length. Cell viability assay show that f-WCNTs induce cell death significantly. We hypothesize that free radicals originated from hydroxyl and carbonyl groups on the surface of f-WCNTs lead cell damage
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