Semifluxons in Superconductivity and Cold Atomic Gases

Josephson junctions and junction arrays are well studied devices in superconductivity. With external magnetic fields one can modulate the phase in a long junction and create traveling, solitonic waves of magnetic flux, called fluxons. Today, it is also possible to device two different types of junctions: depending on the sign of the critical current density, they are called 0- or pi-junction. In turn, a 0-pi junction is formed by joining two of such junctions. As a result, one obtains a pinned Josephson vortex of fractional magnetic flux, at the 0-pi boundary. Here, we analyze this arrangement of superconducting junctions in the context of an atomic bosonic quantum gas, where two-state atoms in a double well trap are coupled in an analogous fashion. There, an all-optical 0-pi Josephson junction is created by the phase of a complex valued Rabi-frequency and we a derive a discrete four-mode model for this situation, which qualitatively resembles a semifluxon.Comment: 15 pages (Latex), 6 color figures (eps

La alianza terapéutica en la terapia de aceptación y compromiso

Acceptance and Commitment Therapy (ACT) is a process-based intervention that promotes psychological flexibility by implementing six core processes. These include acceptance and awareness as well values and behavior change processes. Still, the primary vehicle for implementing these processes is the therapeutic relationship. Underscoring the importance of the relationship is paramount – it is the context in which the interventions emerge, allowing the therapist to shape psychological flexibility directly. We argue that the therapeutic alliance (TA) is co-created and is a critical factor contributing to the effectiveness of ACT. This paper focuses on the TA as a vital part of ACT treatment. We discuss the therapeutic alliance from an ACT perspective, explore different roles in implementing ACT, and conclude with a clinical case illustration. We more specifically focus on how the TA alliance and the therapeutic relationship can be a vehicle of change in ACT.La Terapia de Aceptación y Compromiso (ACT) es una intervención basada en procesos que promueve la flexibilidad psicológica implementando seis procesos centrales. Estos incluyen aceptación y conciencia como también procesos de valores y cambio conductuales. Sin embargo, el vehículo primario para implementar estas intervenciones es la relación terapéutica. En este trabajo discutimos que la Alianza Terapéutica (TA) es co-creada y es un factor crítico que contribuye a la efectividad de la implementación de ACT.  Este artículo se enfoca en la TA como una parte vital del tratamiento ACT. Desarrollamos la alianza terapéutica desde la perspectiva de ACT, exploramos los diferentes roles que ocupa en la implementación de ACT y concluimos con un ejemplo clínico. Mas específicamente mostramos cómo la alianza terapéutica y la relación terapéutica pueden ser un vehículo de cambio en ACT

Formation of Pairing Fields in Resonantly Coupled Atomic and Molecular Bose-Einstein Condensates

In this paper, we show that pair-correlations may play an important role in the quantum statistical properties of a Bose-Einstein condensed gas composed of an atomic field resonantly coupled with a corresponding field of molecular dimers. Specifically, pair-correlations in this system can dramatically modify the coherent and incoherent transfer between the atomic and molecular fields.Comment: 4 pages, 4 figure

Laser-noise-induced correlations and anti-correlations in Electromagnetically Induced Transparency

High degrees of intensity correlation between two independent lasers were observed after propagation through a rubidium vapor cell in which they generate Electromagnetically Induced Transparency (EIT). As the optical field intensities are increased, the correlation changes sign (becoming anti-correlation). The experiment was performed in a room temperature rubidium cell, using two diode lasers tuned to the $^{85}$Rb $D_2$ line ($\lambda = 780$nm). The cross-correlation spectral function for the pump and probe fields is numerically obtained by modeling the temporal dynamics of both field phases as diffusing processes. We explored the dependence of the atomic response on the atom-field Rabi frequencies, optical detuning and Doppler width. The results show that resonant phase-noise to amplitude-noise conversion is at the origin of the observed signal and the change in sign for the correlation coefficient can be explained as a consequence of the competition between EIT and Raman resonance processes.Comment: Accepted for publication in EPJ

Elements of leadership in education : a reflective essay

As I grew up, my interest in various academic subject areas and my enjoyment of school caused me to become interested in education as a career. I felt that I could make a contribution to the lives of my students. My specific interest in mathematics and my personality lent themselves to classroom instruction. Although I have experienced some discouraging days, I still remain confident concerning a career in education

Evolution of a spinor condensate: coherent dynamics, dephasing and revivals

We present measurements and a theoretical model for the interplay of spin dependent interactions and external magnetic fields in atomic spinor condensates. We highlight general features like quadratic Zeeman dephasing and its influence on coherent spin mixing processes by focusing on a specific coherent superposition state in a F=1 $^{87}$Rb Bose-Einstein condensate. In particular, we observe the transition from coherent spinor oscillations to thermal equilibration

Submillimeter wavelength survey of the galactic plane from l = -5 deg to l = +62 deg: Structure and energetics of the inner disk

Results from a large scale survey of the first quadrant of the Milky Way galactic plane at wavelengths of 150, 250, and 300 microns with a 10x10 arcmin beam are presented. The emission detected in the survey arises from compact sources, most of which are identified with known peaks of 5 GHz and/or CO emission, and from an underlying diffuse background with a typical angular width of approximately 0.9 deg (FWHM) which accounts for most of the emission. A total of 80 prominent discrete sources were identified and characterized, of which about half were not previously reported at far infrared wavelengths. The total infrared luminosity within the solar circle is approximately 1 to 2x10 to the 10th power L sub 0, and is probably emitted by dust that resides in molecular clouds

Quantum tunneling of semifluxons

We consider a system of two semifluxons of opposite polarity in a 0-pi-0 long Josephson junction, which classically can be in one of two degenerate states: up-down or down-up. When the distance $a$ between the 0-pi boundaries (semifluxon's centers) is a bit larger than the crossover distance $a_c$, the system can switch from one state to the other due to thermal fluctuations or quantum tunneling. We map this problem to the dynamics of a single particle in a double well potential and estimate parameters for which quantum effects emerge. We also determine the classical-to-quantum crossover temperature as well as the tunneling rate (energy level splitting) between the states up-down and down-up.Comment: submitted to PRB, comments/questions are welcom