68,269 research outputs found
Optimal Controlled Teleportation
We give the analytic expressions of maximal probabilities of successfully
controlled teleportating an unknown qubit via every kind of tripartite states.
Besides, another kind of localizable entanglement is also determined.
Furthermore, we give the sufficient and necessary condition that a three-qubit
state can be collapsed to an EPR pair by a measurement on one qubit, and
characterize the three-qubit states that can be used as quantum channel for
controlled teleporting a qubit of unknown information with unit probability and
with unit fidelity.Comment: 4 page
Probabilistic teleportation of unknown two-particle state via POVM
We propose a scheme for probabilistic teleportation of unknown two-particle
state with partly entangled four-particle state via POVM. In this scheme the
teleportation of unknown two-particle state can be realized with certain
probability by performing two Bell state measurements, a proper POVM and a
unitary transformation.Comment: 5 pages, no figur
Controlled quantum teleportation and secure direct communication
We present a controlled quantum teleportation protocol. In the protocol,
quantum information of an unknown state of a 2-level particle is faithfully
transmitted from a sender (Alice) to a remote receiver (Bob) via an initially
shared triplet of entangled particles under the control of the supervisor
Charlie. The distributed entangled particles shared by Alice, Bob and Charlie
function as a quantum information channel for faithful transmission. We also
propose a controlled and secure direct communication scheme by means of this
teleportation. After insuring the security of the quantum channel, Alice
encodes the secret message directly on a sequence of particle states and
transmits them to Bob supervised by Charlie using this controlled quantum
teleportation. Bob can read out the encoded message directly by the measurement
on his qubit. In this scheme, the controlled quantum teleportation transmits
Alice's message without revealing any information to a potential eavesdropper.
Because there is not a transmission of the qubit carrying the secret message
between Alice and Bob in the public channel, it is completely secure for
controlled and direct secret communication if perfect quantum channel is used.
The feature of this scheme is that the communication between two sides depends
on the agreement of the third side.Comment: 4 page
Cost-effectiveness of osimertinib versus standard EGFR-TKI as first-line treatment for locally advanced or metastatic EGFR mutation-positive non-small cell lung cancer in Australia.
Objectives: To assess the cost-effectiveness of osimertinib versus standard epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), gefitinib or erlotinib, as first-line treatment for patients with locally advanced or metastatic EGFR mutation-positive non-small cell lung cancer in Australia from a healthcare system perspective. Methods: A partitioned survival model comprising three mutually exclusive health states with a five-year time horizon was developed. Model inputs were sourced from the pivotal trial (FLAURA) and published literature. Incremental cost-effectiveness ratios (ICERs), in terms of cost per quality-adjusted life-year (QALY) gained and cost per life-year (LY) gained, were calculated. Uncertainty of the results was assessed using deterministic and probabilistic sensitivity analyses. Results: Compared with standard EGFR-TKIs, osimertinib was associated with a higher incremental cost of A432,197/QALY gained and A50,000/QALY, first-line osimertinib is not cost-effective compared with standard EGFR-TKIs in Australia based on the current published price. To achieve acceptable cost-effectiveness, the cost of first-line osimertinib needs to be reduced by at least 68.4%
Modeling the Optical Afterglow of GRB 030329
The best-sampled afterglow light curves are available for GRB 030329. A
distinguishing feature of this event is the obvious rebrightening at around 1.6
days after the burst. Proposed explanations for the rebrightening mainly
include the two-component jet model and the refreshed shock model, although a
sudden density-jump in the circumburst environment is also a potential choice.
Here we re-examine the optical afterglow of GRB 030329 numerically in light of
the three models. In the density-jump model, no obvious rebrightening can be
produced at the jump moment. Additionally, after the density jump, the
predicted flux density decreases rapidly to a level that is significantly below
observations. A simple density-jump model thus can be excluded. In the
two-component jet model, although the observed late afterglow (after 1.6 days)
can potentially be explained as emission from the wide-component, the emergence
of this emission actually is too slow and it does not manifest as a
rebrightening as previously expected. The energy-injection model seems to be
the most preferred choice. By engaging a sequence of energy-injection events,
it provides an acceptable fit to the rebrightening at d, as well as
the whole observed light curve that extends to d. Further studies on
these multiple energy-injection processes may provide a valuable insight into
the nature of the central engines of gamma-ray bursts.Comment: 18 pages, 3 figures; a few references added and minor word changes;
now accepted for publication in Ap
Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas
The Luther-Emery liquid is a state of matter that is predicted to occur in
one-dimensional systems of interacting fermions and is characterized by a
gapless charge spectrum and a gapped spin spectrum. In this Letter we discuss a
realization of the Luther-Emery phase in a trapped cold-atom gas. We study by
means of the density-matrix renormalization-group technique a two-component
atomic Fermi gas with attractive interactions subject to parabolic trapping
inside an optical lattice. We demonstrate how this system exhibits compound
phases characterized by the coexistence of spin pairing and atomic-density
waves. A smooth crossover occurs with increasing magnitude of the atom-atom
attraction to a state in which tightly bound spin-singlet dimers occupy the
center of the trap. The existence of atomic-density waves could be detected in
the elastic contribution to the light-scattering diffraction pattern.Comment: 10 pages, 3 figures, 1 Table, submitted to Phys. Rev. on July 25th
200
Quantum-defect theory of resonant charge exchange
We apply the quantum-defect theory for potential to study the
resonant charge exchange process. We show that by taking advantage of the
partial-wave-insensitive nature of the formulation, resonant charge exchange of
the type of S+S can be accurately described over a wide range of
energies using only three parameters, such as the \textit{gerade} and the
\textit{ungerade} wave scattering lengths, and the atomic polarizability,
even at energies where many partial waves contribute to the cross sections. The
parameters can be determined experimentally, without having to rely on accurate
potential energy surfaces, of which few exist for ion-atom systems. The theory
further relates ultracold interactions to interactions at much higher
temperatures.Comment: 8 pages, 7 figure
Interacting Fermi Gases in Disordered One-Dimensional Lattices
Interacting two-component Fermi gases loaded in a one-dimensional (1D)
lattice and subject to harmonic trapping exhibit intriguing compound phases in
which fluid regions coexist with local Mott-insulator and/or band-insulator
regions. Motivated by experiments on cold atoms inside disordered optical
lattices, we present a theoretical study of the effects of a random potential
on these ground-state phases. Within a density-functional scheme we show that
disorder has two main effects: (i) it destroys the local insulating regions if
it is sufficiently strong compared with the on-site atom-atom repulsion, and
(ii) it induces an anomaly in the compressibility at low density from quenching
of percolation.Comment: 7 pages, 4 figures, submitte
- …