Letter from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro

Letter from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro. Letter has handwritten notes and includes a Library of Congress translation.https://ir.lawnet.fordham.edu/vice_presidential_campaign_correspondence_1984_international/1344/thumbnail.jp

Simple factorization of unitary transformations

We demonstrate a method for general linear optical networks that allows one to factorize any SU($n$) matrix in terms of two SU($n-1)$ blocks coupled by an SU(2) entangling beam splitter. The process can be recursively continued in an efficient way, ending in a tidy arrangement of SU(2) transformations. The method hinges only on a linear relationship between input and output states, and can thus be applied to a variety of scenarios, such as microwaves, acoustics, and quantum fields.Comment: 5 pages, 4 figures. Comments welcome

Inequivalent classes of closed three-level systems

We show here that the $\Lambda$ and V configurations of three-level atomic systems, while they have recently been shown to be equivalent for many important physical quantities when driven with classical fields [M. B. Plenio, Phys. Rev. A \textbf{62}, 015802 (2000)], are no longer equivalent when coupled via a quantum field. We analyze the physical origin of such behavior and show how the equivalence between these two configurations emerges in the semiclassical limit.Comment: 4 pages, 1 figure. To appear as Brief Report in Physical Review

Voltage balance and control in a multi-level unified power flow controller

Published versio

Extremal states for photon number and quadratures as gauges for nonclassicality

Rotated quadratures carry the phase-dependent information of the electromagnetic field, so they are somehow conjugate to the photon number. We analyze this noncanonical pair, finding an exact uncertatinty relation, as well as a couple of weaker inequalities obtained by relaxing some restrictions of the problem. We also find the intelligent states saturating that relation and complete their characterization by considering extra constraints on the second-order moments of the variables involved. Using these moments, we construct performance measures tailored to diagnose photon-added and Schr\"odinger catlike states, among others.Comment: 6 pages, 4 color figures. Comments welcome

Unpolarized states and hidden polarization

We capitalize on a multipolar expansion of the polarisation density matrix, in which multipoles appear as successive moments of the Stokes variables. When all the multipoles up to a given order $K$ vanish, we can properly say that the state is $K$th-order unpolarized, as it lacks of polarization information to that order. First-order unpolarized states coincide with the corresponding classical ones, whereas unpolarized to any order tally with the quantum notion of fully invariant states. In between these two extreme cases, there is a rich variety of situations that are explored here. The existence of \textit{hidden} polarisation emerges in a natural way in this context.Comment: 7 pages, 3 eps-color figures. Submitted to PRA. Comments welcome

Telegram from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro

Telegram from Matilde M. de Soto and Maria Lydia Sanchez de Roman, Deputies of the Costa Rican Legislative Assembly, to Geraldine Ferraro. Telegram includes Library of Congress translation.https://ir.lawnet.fordham.edu/vice_presidential_campaign_correspondence_1984_international/1345/thumbnail.jp

Orbital angular momentum from marginals of quadrature distributions

We set forth a method to analyze the orbital angular momentum of a light field. Instead of using the canonical formalism for the conjugate pair angle-angular momentum, we model this latter variable by the superposition of two independent harmonic oscillators along two orthogonal axes. By describing each oscillator by a standard Wigner function, we derive, via a consistent change of variables, a comprehensive picture of the orbital angular momentum. We compare with previous approaches and show how this method works in some relevant examples.Comment: 7 pages, 2 color figure

Lost and found: the radial quantum number of Laguerre-Gauss modes

We introduce an operator linked with the radial index in the Laguerre-Gauss modes of a two-dimensional harmonic oscillator in cylindrical coordinates. We discuss ladder operators for this variable, and confirm that they obey the commutation relations of the su(1,1) algebra. Using this fact, we examine how basic quantum optical concepts can be recast in terms of radial modes.Comment: Some minor typos fixed