3,566 research outputs found
Symbiotic stars as possible progenitors of SNe Ia: binary parameters and overall outlook
Symbiotic stars are interacting binaries in which the first-formed white
dwarf accretes and burns material from a red giant companion. This paper aims
at presenting physical characteristics of these objects and discussing their
possible link with progenitors of type Ia supernovae.Comment: 4 pages. Invited rewiev at "Binary Paths to Type Ia Supernovae", IAU
Symposium No. 281, R. Di Stefano & M. Orio, eds., Cambridge University Pres
A non-Markovian optical signature for detecting entanglement in coupled excitonic qubits
We identify an optical signature for detecting entanglement in experimental
nanostructure systems comprising coupled excitonic qubits. This signature owes
its strength to non-Markovian dynamical effects in the second-order temporal
coherence function of the emitted radiation. We calculate autocorrelation and
cross-correlation functions for both selective and collective light excitation,
and prove that the coherence properties of the emitted light do indeed carry
information about the entanglement of the initial multi-qubit state.
We also show that this signature can survive in the presence of a noisy
environment.Comment: 4 pages, 4 color figures. Minor changes. Accepted version to be
published in Europhysics Letter
Ultrafast optical signature of quantum superpositions in a nanostructure
We propose an unambiguous signature for detecting quantum superposition
states in a nanostructure, based on current ultrafast spectroscopy techniques.
The reliable generation of such superposition states via Hadamard-like quantum
gates is crucial for implementing solid-state based quantum information
schemes. The signature originates from a remarkably strong photon antibunching
effect which is enhanced by non-Markovian dynamics.Comment: 4 pages, 2 figures. Published in Phys. Rev. B (Rapid Communications
Direct equivalence between quantum phase transition phenomena in radiation-matter and magnetic systems: scaling of entanglement
We show that the quantum phase transition arising in a standard
radiation-matter model (Dicke model) belongs to the same universality class as
the infinitely-coordinated, transverse field XY model. The effective
qubit-qubit exchange interaction is shown to be proportional to the square of
the qubit-radiation coupling. A universal finite-size scaling is derived for
the corresponding two-qubit entanglement (concurrence) and a size-consistent
effective Hamiltonian is proposed for the qubit subsystem.Comment: 4 pages, 3 figures. Minor changes. Published versio
Testing collinear factorization and nuclear parton distributions with pA collisions at the LHC
Global perturbative QCD analyses, based on large data sets from
electron-proton and hadron collider experiments, provide tight constraints on
the parton distribution function (PDF) in the proton. The extension of these
analyses to nuclear parton distributions (nPDF) has attracted much interest in
recent years. nPDFs are needed as benchmarks for the characterization of hot
QCD matter in nucleus-nucleus collisions, and attract further interest since
they may show novel signatures of non- linear density-dependent QCD evolution.
However, it is not known from first principles whether the factorization of
long-range phenomena into process-independent parton distribution, which
underlies global PDF extractions for the proton, extends to nuclear effects. As
a consequence, assessing the reliability of nPDFs for benchmark calculations
goes beyond testing the numerical accuracy of their extraction and requires
phenomenological tests of the factorization assumption. Here we argue that a
proton-nucleus collision program at the LHC would provide a set of measurements
allowing for unprecedented tests of the factorization assumption underlying
global nPDF fits.Comment: 4 pages, 5 figure
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