1,721,742 research outputs found
Population dynamics based on ladder bosonic operators
Full text linkWe adopt an operatorial method, based on truncated bosons, to describe the dynamics of populations in a closed region with a non trivial topology. The main operator that includes the various mechanisms and interactions between the populations is the Hamiltonian, constructed with the density and transport operators. The whole evolution is derived from the Schrödinger equation, and the densities of the populations are retrieved from the normalized expected values of the density operators. We show that this approach is suitable for applications in very large domain, solving the computational issues that typically occur when using an Hamiltonian based on fermionic ladder operators
Morphobathymetric and structural analysis of the Ustica Island offshore (southern Tyrrhenian sea)
No full textBi-coherent states as generalized eigenstates of the position and the momentum operators
Full text linkIn this paper, we show that the position and the derivative operators, q^ and D^ , can be treated as ladder operators connecting various vectors of two biorthonormal families, Fφ and Fψ. In particular, the vectors in Fφ are essentially monomials in x, xk, while those in Fψ are weak derivatives of the Dirac delta distribution, δ(m)(x) , times some normalization factor. We also show how bi-coherent states can be constructed for these q^ and D^ , both as convergent series of elements of Fφ and Fψ, or using two different displacement-like operators acting on the two vacua of the framework. Our approach generalizes well- known results for ordinary coherent states
Dynamics for a quantum parliament
Full text linkIn this paper we propose a dynamical approach based on the
Gorini-Kossakowski-Sudarshan-Lindblad equation for a problem of decision
making. More specifically, we consider what was recently called a quantum
parliament, asked to approve or not a certain law, and we propose a model of
the connections between the various members of the parliament, proposing in
particular some special form of the interactions giving rise to a {\em
collaborative} or non collaborative behaviour
Extended coupled SUSY, pseudo-bosons and weak squeezed states
Full text linkIn this paper we consider squares of pseudo-bosonic ladder operators and we
use them to produce explicit examples of eigenstates of certain operators
satisfying a deformed Lie algebra. We show how these
eigenstates may, or may not, be square-integrable. In both cases, a notion of
biorthonormality can be introduced and analyzed. Some examples are discussed in
details. We also propose some preliminary results on bi-squeezed states arising
from our operators.Comment: arXiv admin note: text overlap with arXiv:2102.1173
DEFICIT DI CONOSCENZE RELATIVE ALLE MODALITÀ DI TRASMISSIONE DELLE EPATITI B – C. RUOLO DI EDUCATORE SANITARIO DELL’INFERMIERE
No full textA TWDM-PON with Advanced Modulation Techniques and a Multi-Pump Raman Amplifier for Cost-Effective Migration to Future UDWDM-PONs
No full textDense wavelength-division multiplexing passive optical networks and ultra-dense wavelength-division multiplexing passive optical networks are strong candidates to future nextgeneration passive optical network stage 3 access networks in order to satisfy increasing bandwidth demand, but their deployment is still a great challenge for telecommunication operators. Time and wavelength division multiplexed PON (TWDM-PON) has already been chosen by ITU-T as one of the best architectures in brownfield contexts to allow the reuse of the optical distribution network. Our proposal exploits the advantages of TWDM in order to reach a balance between coexistence with legacy systems and gradual and cost-effective migration towards pure wavelength division multiplexed PON (WDM-PON). In order to fulfill this aim, with reference to downstream traffic enhancement, two main novelties are presented: 1) the use of a multi-pump Raman amplifier (MRA) to satisfy the future necessity of large gain bandwidth; 2) the introduction of advanced modulation techniques to increase spectral efficiency and the future number of user channels (a less than 7 GHz-wide channel bandwidth providing 10 Gb/s bitrate has been demonstrated). A coherent system has been also proposed and its main impairments have been evaluated. The MRA has been accurately optimized to minimize power consumption without compromising performances. In the upstream direction, a semiconductor optical amplifier has been considered. The performances of the proposed TWDM-PON have been predicted through numerical simulations based on a system-level commercial CAD software
Coherent states of graphene layer with and without a PT-symmetric chemical potential
Full text linkIn this paper we construct different classes of coherent and bicoherent states for the graphene
tight-binding model in presence of a magnetic field, and for a deformed version where we
include a PT -symmetric chemical potential V . In particular, the problems caused by the absence
of a suitable ground state for the system is taken into account in the construction of these states,
for V = 0 and for V ≠ 0. We introduce ladder operators which work well in our context, and we
show, in particular, that there exists a choice of these operators which produce a factorization
of the Hamiltonian. The role of broken and unbroken PT -symmetry is discussed, in connection
with the strength of V
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