670 research outputs found
Quantum state redistribution based on a generalized decoupling
We develop a simple protocol for a one-shot version of quantum state
redistribution, which is the most general two-terminal source coding problem.
The protocol is simplified from a combination of protocols for the fully
quantum reverse Shannon and fully quantum Slepian-Wolf problems, with its
time-reversal symmetry being apparent. When the protocol is applied to the case
where the redistributed states have a tensor power structure, more natural
resource rates are obtained
Exploration of nonlocalities in ensembles consisting of bipartite quantum states
It is revealed that ensembles consisting of multipartite quantum states can
exhibit different kinds of nonlocalities. An operational measure is introduced
to quantify nonlocalities in ensembles consisting of bipartite quantum states.
Various upper and lower bounds for the measure are estimated and the exact
values for ensembles consisting of mutually orthogonal maximally entangled
bipartite states are evaluated.Comment: The title and some contents changed, 4 pages, no figure
Robust interface between flying and topological qubits
Hybrid architectures, consisting of conventional and topological qubits, have
recently attracted much attention due to their capability in consolidating the
robustness of topological qubits and the universality of conventional qubits.
However, these two kinds of qubits are normally constructed in significantly
different energy scales, and thus this energy mismatch is a major obstacle for
their coupling that supports the exchange of quantum information between them.
Here, we propose a microwave photonic quantum bus for a direct strong coupling
between the topological and conventional qubits, in which the energy mismatch
is compensated by the external driving field via the fractional ac Josephson
effect. In the framework of tight-binding simulation and perturbation theory,
we show that the energy splitting of the topological qubits in a finite length
nanowire is still robust against local perturbations, which is ensured not only
by topology, but also by the particle-hole symmetry. Therefore, the present
scheme realizes a robust interface between the flying and topological qubits.
Finally, we demonstrate that this quantum bus can also be used to generate
multipartitie entangled states with the topological qubits.Comment: Accepted for publication in Scientific Report
Exploring multipartite quantum correlations with the square of quantum discord
We explore the quantum correlation distribution in multipartite quantum
states based on the square of quantum discord (SQD). For tripartite quantum
systems, we derive the necessary and sufficient condition for the SQD to
satisfy the monogamy relation. Particularly, we prove that the SQD is
monogamous for three-qubit pure states, based on which a genuine tripartite
quantum correlation measure is introduced. In addition, we also address the
quantum correlation distributions in four-qubit pure states. As an example, we
investigate multipartite quantum correlations in the dynamical evolution of
multipartite cavity-reservoir systems.Comment: 8 pages, 5 figure
Entanglement in a class of multiqubit mixed states without multipartite tangles
Based on quantum complementary relations (QCRs) and a purification scenario,
we analyze a class of N-qubit mixed states that are entangled but do not have
two-, and genuine three-, four-, ..., N-qubit entanglements. It is shown that
entanglement (one-tangle or negativity) in these mixed states is closely
related to the QCR entanglement of their purified states. In particular, it is
elaborated that when the mixed state does not have multipartite tangles (two-
and higher tangles), its entanglement is actually a kind of genuine
multipartite QCR entanglement between the system and its environment.Comment: 5 pages, 3 figures, version
Strong quantum fluctuation of vortices in the new superconductor
By using transport and magnetic measurement, the upper critical field
and the irreversibility line has been determined. A
big separation between and has been found showing the
existence of a quantum vortex liquid state induced by quantum fluctuation of
vortices in the new superconductor . Further investigation on the
magnetic relaxation shows that both the quantum tunneling and the thermally
activated flux creep weakly depends on temperature. But when the melting field
is approached, a drastic rising of the relaxation rate is observed.
This may imply that the melting of the vortex matter at a finite temperature is
also induced by the quantum fluctuation of vortices.Comment: 4 pages, 4 figure
SiC Nanorods Grown on Electrospun Nanofibers Using Tb as Catalyst: Fabrication, Characterization, and Photoluminescence Properties
Well-crystallizedβ-SiC nanorods grown on electrospun nanofibers were synthesized by carbothermal reduction of Tb doped SiO2(SiO2:Tb) nanofibers at 1,250 °C. The as-synthesized SiC nanorods were 100–300 nm in diameter and 2–3 μm in length. Scanning electron microscopy (SEM) results suggested that the growth of the SiC nanorods should be governed by vapor-liquid-solid (VLS) mechanism with Tb metal as catalyst. Tb(NO3)3particles on the surface of the electrospun nanofibers were decomposed at 500 °C and later reduced to the formation of Tb nanoclusters at 1,200 °C, and finally the formation of a Si–C–Tb ally droplet will stimulate the VLS growth at 1,250 °C. Microstructure of the nanorod was further investigated by transmission electron microscopy (TEM). It was found that SiC <111> is the preferred initial growth direction. The liquid droplet was identified to be Si86Tb14, which acted as effective catalyst. Strong green emissions were observed from the SiC nanorod samples. Four characteristic photoluminescence (PL) peaks of Tb ions were also identified
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