Jorge Aliaga

Jorge Aliaga
Universidad de Buenos Aires | UBA · Department of Physics (FCEN)

PhD

About

42
Publications
2,750
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
558
Citations
Introduction

Publications

Publications (42)
Article
Full-text available
We describe a low cost design of an electronic neuron, which is designed to represent the dynamical properties of the membrane potential of biological neurons by modeling the states of the membrane channels. This electronic neuron can be used to study the nonlinear properties of the membrane voltage dynamics and to develop and analyze small neurona...
Article
Full-text available
We present a biologically inspired electronic neuron based on a conductance model. The channels are constructed using linearly voltage controlled field effect transistors. A two channel and a three channel circuit is developed. The dynamical behavior of this system is studied, showing for the two channel circuit either class-I or class-II excitabil...
Article
Full-text available
In this work we present an electronic syrinx: an analogical integrator of the equations describing a model for sound production by oscine birds. The model depends on time varying parameters with clear biological interpretation: the air sac pressure and the tension of ventral syringeal muscles. We test the hypothesis that these physiological paramet...
Article
Full-text available
Recently, it was proposed that semiconductor lasers with optical feedback present a complex behavior that can be described as noise driven excitable. In this work we investigate in which region of parameter space this description is adequate. We conclude that the region of the parameter space in which the system displays noise driven excitable beha...
Article
In this paper we define, in the context of dynamical algebras, a set of operators that are suitable for studying any relevant quantity related to the two-level Jaynes–Cummings model (JCM). We study the usual JCM with and without the rotating wave approximation (RWA), and then we add the presence of an external field. In this last case we find that...
Article
Full-text available
We show that the uncertainty determined by the minimum division of a measuring instrument can be diminished by using dithering. We present a numerical example to introduce the technique and two experiments that show how the precision is enhanced.
Article
We report the construction of an electronic device that models and replaces a neuron in a midbody ganglion of the leech Hirudo medicinalis. In order to test the behavior of our device, we used a well-characterized synaptic interaction between the mechanosensory, sensitive to pressure, (P) cell and the anteropagoda (because of the action potential s...
Article
In this article we propose a very simple scheme for detecting the state and the degree of entanglement of two modes of radiation using a beam splitter. We find that using this device we can tell whether the state coming out of a certain apparatus is maximally entangled, by measuring the intensity of the radiation of one of the modes. This result is...
Article
Full-text available
In this Letter we extend the concept of stochastic resonance. We show that in forced excitable systems noise can be responsible for the appearance of recurrences presenting a robust topological organization inequivalent to the periodic orbits of the deterministic system. As in stochastic resonance, these new structures are most pronounced at an opt...
Article
Full-text available
Recently it was proposed that semiconductor lasers with optical feedback present a regime where they behave as noise driven excitable units. In this work we report on an experimental study in which we periodically force one of these lasers and we compare the results with the solutions of a simple model. The comparison is based on a topological anal...
Article
Full-text available
In this paper we study a two-photon time-dependent Jaynes-Cummings model interacting with a Kerr-like medium. We assumed that the electromagnetic field is in different states such as coherent, squeezed vacuum and pair coherent, and that the atom is initially in the excited state. We studied the temporal evolution of the population of the excited le...
Article
Full-text available
We generate an observable which relates the interspike time statistics in a noise driven excitable system with its phase space global properties. Experimental results from a semiconductor laser with optical feedback are analyzed within this framework.
Article
Full-text available
We show that the Stark and Kerr Hamiltonians are deeply connected in the framework of dynamical algebras. We found that the algebras for both Hamiltonians are the same when physically relevant magnitudes, such as the population inversion and the nth order coherence function are considered as elements of a Lie algebra under commutation with the Hami...
Article
Full-text available
We study a quantum-mechanical system, prepared, at t0, in a model state, that subsequently decays into a sea of other states whose energy levels form a discrete spectrum with given statistical properties. An important quantity is the survival probability P(t), defined as the probability, at time t, to find the system in the original model state. Ou...
Article
Full-text available
We demonstrate that the dynamics of the Ξ and Λ non-degenerate two-photon time-dependent Jaynes-Cummings models are characterized by the bidimensional Fibonacci-like connection between quantal correlations of different orders. The time-independent cases are solved and infinite sets of invariants of motion are obtained. The close dynamical relations...
Article
Full-text available
We show that the dissipative dynamics observed in a small quantum system coupled to a large one (the bath) is a consequence of increasing the size of the bath. We exemplify this effect with a quantum harmonic oscillator coupled to N harmonic oscillators. We find that revivals in the level population exist and give an estimate of their period. For l...
Article
Full-text available
The dynamics and thermodynamics of a quantum time-dependent field coupled to a two-level system, well known as the Jaynes-Cummings Hamiltonian, is studied, using the maximum entropy principle. In the framework of this approach we found three different infinite sets of relevant operators that describe the dynamics of the system for any temporal depe...
Article
Full-text available
The addition of a nonlinear term to the Jaynes-Cummings Hamiltonian induced a nontrivial discrete dynamics for the number of possible transitions of a given order, represented by a Fibonacci series. We describe the physics of the problem in terms of relevant operators which close a semi-Lie algebra under commutation with the Hamiltonian and therefo...
Article
A wave-function approach to the interaction Hamiltonian for the degenerate parametric amplifier has been recently presented [C. G. Bollini and L. E. Oxman, Phys. Rev. A 47, 2339 (1993)]. We want to show here that a maximum entropy principle density matrix approach can be used to reobtain all the results shown in this reference, and also to avoid th...
Article
Full-text available
A maximum entropy principle density matrix method, valid for systems with temperature different from zero, is presented making it possible to find two-mode squeezed states in two-level systems with relevant operators and Hamiltonian connected with O(3,2). A method which allows one to relate the appearance of squeezing to the relevant operators, inc...
Article
Full-text available
A time-dependent generalization of the Jaynes-Cummings Hamiltonian is studied using the maximum entropy formalism. The approach, related to a semi-Lie algebra, allows one to find three differentsets of physically relevant operators which describes the dynamics of the system for any temporal dependence. It is shown how the initial conditions of the...
Article
Coherent and squeezed states for the time-dependent-frequency harmonic oscillator are analyzed using maximum entropy principle techniques. The information-theoretic procedure leads to results equivalent to that of the Wigner-function formalism, although the former gives a physical interpretation of the involved parameters and allows for a nonzero-t...
Chapter
Full-text available
The Maximum Entropy Principle (MEP) formalism is applied in order to solve time-dependent N-level systems. The formalism, related to a cuasi-Lie algebra, allows us to find not only the dynamical equations of the relevant operators for any temporal dependence of the interaction between levels, but also to diagonalize the associated off-equilibrium (...
Chapter
The electronic properties in a metallic system close to the metal-insulator transition play a crucial role in high Tc superconductor theory. Among others, the Hubbard model has been extensively studied using different methods [1–8]. In particular, the one-dimensional Hubbard Hamiltonian (H-H) is considered as the most simplified model able to treat...
Chapter
The description of the well-known degenerate parametric amplifier is given in terms of the density matrix approach (1-3) to the interaction picture. This description allows for a thermodynamical analysis of the dynamical evolutions of the system for different initial conditions. The appearance of squeezed and coherent states is studied. (4-5)
Article
A reformulation of the well-known maximum-entropy principle in the interaction picture is shown. The advantage of this approach for the case in which the relevant operators in the interaction picture do not depend explicitly on time is stated. As an example, we study the dynamical evolution of the dispersions of the so-called slowly varying quadrat...
Article
Full-text available
The maximum entropy principle formalism is applied in order to solve time-dependent N-level systems. The formalism, related to a quasi-Lie algebra, allows us to find not only the dynamical equations of the relevant operators for any temporal dependence of the interaction between levels, but also to diagonalize the associated off-equilibrium (temper...
Article
Recently, De Brito and Baseia [Phys. Rev. A 40, 4097 (1989)] have studied the appearance of squeezed states for the Bateman Hamiltonian. Although the final results obtained in that report are correct, it is our intention to use an alternative point of view, based on a density matrix defined according to the maximum entropy principle, which allows u...
Chapter
The discovery of superconductivity in heavy-fermion systems and in copper oxides has stimulated not only the experimental but also the theoretical work on the mechanism which induces the phenomena. The Anderson1 and Hubbard2 models are two of the most broadly used. In particular, the interplay of the Coulomb interaction and disorder is analyzed usi...
Chapter
We present a density matrix method, based on information-theory, which makes it possible to find non-zero temperature coherent and squeezed states for the harmonic oscillator (HO) with time-dependent frequency, the Kanai-Caldirola (KC) Hamiltonian, and isomorphic ones. We establish a connection between the appearance of squeezed states and the rele...
Article
Using the maximum-entropy approach, we analyze the appearance of coherent and squeezed states for the Kanai-Caldirola Hamiltonian, making it possible to extend the analysis easily to the so-called generalized harmonic oscillator and a sort of two-photon Hamiltonian, for both the zero and nonzero temperature cases. A connection between the possibili...
Article
We present a density-matrix method, based on information theory, which makes it possible to find nonzero-temperature coherent and squeezed states for the harmonic oscillator with time-dependent frequency. We establish a connection between the appearance of squeezed states and the relevant operators included in the density matrix, compare our result...
Chapter
The application of Information-Theory techniques to problems of Hamiltonian dynamics have provided one with interesting new insights.
Article
A density matrix method, valid for systems with temperature different from zero, is presented making it possible to find squeezing in systems with relevant operators and Hamiltonian connected with SU (1,1) and isomorphics. A method which allows one ro relate the appearance of squeezing to the relevant operators included in order to define the densi...
Article
A simplified Hamiltonian model of pair tunneling between two weakly coupled superconductors is used to obtain the ac Josephson current. A closed operator algebra is defined through commutation with the Hamiltonian. With the use of information theory, we find a subalgebra (quasi-angular-momentum operators) that allows us to obtain naturally the depe...
Article
An information-theoretic approach is used to give a straightforward procedure that allows one to determine whether dissipative behavior can be attained for a given Hamiltonian. This technique stresses the importance of an adequate set of initial conditions in order to obtain dissipative evolution. It is shown that, although dissipative solutions ma...
Article
On the basis of the maximum-entropy principle, the usual definition of temperature is extended to quantal systems. Entropy, specific heats, and state equations are evaluated for bounded (i.e., spinorial systems) and unbounded operators (i.e., electromagnetic field systems).
Article
A method to construct relevant Hilbert subspaces for unbounded operators is developed. The thermodynamical properties of systems described by density matrices built up out of such operators are studied. Edge effects that arise as a consequence of projections onto finite Hilbert subspaces are also carefully analyzed.
Article
Dynamical aspects of the entropy are discussed within the information-theory context. General invariants of the motion are formulated and related both to the entropy and to the number of accessible states. Examples on finite systems (Schottky anomaly, echo spins) are presented. The entropy evolution through nonequilibrium states is also discussed.
Article
A simple method to separate the K X-ray emitted from fragments in flight or trapped in the backing of the source is developed, for those cases in which a transmission source is not available.

Network

Cited By