34 research outputs found
Energy consumption for ion transport in a segmented Paul trap
There is recent interest in determining energy costs of shortcuts to
adiabaticity (STA), but different definitions of "cost" have been used. We
demonstrate the importance of taking into account the Control System (CS) for a
fair assessment of energy flows and consumptions. We model the energy
consumption and power to transport an ion by a STA protocol in a multisegmented
Paul trap. The ion is driven by an externally controlled, moving harmonic
oscillator. Even if no net ion- energy is gained at destination, setting the
time-dependent control parameters is a macroscopic operation that costs energy
and results in energy dissipation for the short time scales implied by the
intrinsically fast STA processes. The potential minimum is displaced by
modulating the voltages on control (dc) electrodes. A secondary effect of the
modulation, usually ignored as it does not affect the ion dynamics, is the
time- dependent energy shift of the potential minimum. The non trivial part of
the energy consumption is due to the electromotive forces to set the electrode
voltages through the low-pass filters required to preserve the electronic noise
from decohering the ion's motion. The results for the macroscopic CS (the Paul
trap) are compared to the microscopic power and energy of the ion alone.
Similarities are found -and may be used quantitatively to minimize costs- only
when the CS-dependent energy shift of the harmonic oscillator is included in
the ion energy
High-Resolution NMR Spectroscopy at Large Fields with Nitrogen Vacancy Centers
Ensembles of nitrogen-vacancy (NV) centers are used as sensors to detect NMR
signals from micron-sized samples at room temperature. In this scenario, the
regime of large magnetic fields is especially interesting as it leads to a
large nuclear thermal polarisation -- thus, to a strong sensor response even in
low concentration samples -- while chemical shifts and J-couplings become more
accessible. Nevertheless, this regime remains largely unexplored owing to the
difficulties to couple NV-based sensors with high-frequency nuclear signals. In
this work, we circumvent this problem with a method that maps the relevant
energy shifts in the amplitude of an induced nuclear spin signal that is
subsequently transferred to the sensor. This stage is interspersed with
free-precession periods of the sample nuclear spins where the sensor does not
participate. Thus, our method leads to high spectral resolutions ultimately
limited by the coherence of the nuclear spin signal.Comment: 6 pages, 3 figure
Time-dependent harmonic potentials for momentum or position scaling
Cooling methods and particle slowers as well as accelerators are basic tools
for fundamental research and applications in different fields and systems. We
put forward a generic mechanism to scale the momentum of a particle, regardless
of its initial position and momentum, by means of a transient harmonic
potential. The design of the time-dependent frequency makes use of a linear
invariant and inverse techniques drawn from ''shortcuts to adiabaticity''. The
timing of the process may be decided beforehand and its influence on the system
evolution and final features is analyzed. We address quantum systems but the
protocols found are also valid for classical particles. Similar processes are
possible as well for position scaling
Tailored Ion Beam for Precise Color Center Creation
We present a unitary quantum control scheme that produces a highly
monochromatic ion beam from a Paul trap. Our protocol is implementable by
supplying the segmented electrodes with voltages of the order of Volts, which
mitigates the impact of fluctuating voltages in previous designs and leads to a
low-dispersion beam of ions. Moreover, our proposal does not rely on
sympathetically cooling the ions, which bypasses the need of loading different
species in the trap -- namely, the propelled ion and, e.g., a Ca
atom able to exert sympathetic cooling -- incrementing the repetition rate of
the launching procedure. Our scheme is based on an invariant operator linear in
position and momentum, which enables us to control the average extraction
energy and the outgoing momentum spread. In addition, we propose a sequential
operation to tailor the transversal properties of the beam before the ejection
to minimize the impact spot and to increase the lateral resolution of the
implantation
El litoral como espacio productivo. El caso de Cartagena
El litoral ha constituido a lo largo de la historia una importante fuente de recursos económicos además de un área estratégica para la defensa del territorio. Durante el siglo XIX, en paralelo al proceso de industrialización y sin perder su valor defensivo, el litoral resurge como fuente de recursos económicos y productivos con un alto grado de accesibilidad vinculado al transporte marítimo, y como elemento de ocio y disfrute personal (baños de mar y deportes náuticos). Estas transformaciones económicas y sociales van a provocar un cambio significativo en la relación entre el hombre y la costa respaldado por la transformación del marco normativo: el valor estratégico de la costa dará lugar desde el origen del derecho civil moderno, a la recuperación del concepto de Dominio Público Marítimo Terrestre, así como a la regulación de usos y limitaciones a la propiedad litoral. Desde la triple perspectiva del litoral como sistema físico natural, económico cultural y administrativo y legal, el principal objetivo de la presente comunicación será señalar las pautas en el proceso de transformación del litoral consecuencia de la evolución en la forma de producción del espacio, de área defensiva a recurso productivo, y desde mediados del siglo XIX hasta el día de hoy en la costa de Cartagena. Además de la antigüedad en el origen del desarrollo de algunas de las principales actividades económicas vinculadas al litoral (industria pesquera y del salazón, extracción minera y actividad comercial y defensiva con base en el Puerto de Cartagena), destacan algunos hechos significativos que ponen de manifiesto el interés de este tramo de costa como laboratorio de operaciones en el diseño de modelos de explotación del litoral: Bahía de Portmán, Valle de las Escombreras, CITN de la Manga del Mar Menor y San Ginés, Campo de Cartagena, etc
Fréquentations des grottes durant l’époque romaine: le cas de la Navarre
El estudio de la ocupación de las cuevas ha copado el interés de los
investigadores desde el siglo XIX. Sin embargo, han sido los niveles prehistóricos
los que han gozado de un mayor protagonismo, dejando en un segundo
plano los vestigios postpaleolíticos. Si bien en los últimos años se está aumentando
el número de publicaciones sobre la frecuentación de las cuevas en época
romana y medieval, en Navarra es un tema muy poco estudiado. Es por ello
que el siguiente artículo pretende cubrir, al menos en parte, ese vacío historiográfico.
Así, en este texto, presentamos una primera aproximación al estudio de
la frecuentación de las cuevas en época romana en Navarra.The study of the caves occupation has cornered the interest of the researchers since the 19th century. Nevertheless, their prehistoric levels are which have been the biggest interest, leaving in a background the post‐Paleolithic vestiges. Although, the last years, the number of publications about the frequentness of the caves in roman and medieval epoch has increased. However, in Navarre it is a topic very slightly studied. The following article tries to cover this emptiness of the research. This text is our first approximation to the study about the frequentness of the caves in roman epoch in Navarre.
Vanishing efficiency of a speeded-up ion-in-Paul-trap Otto engine
We assess the energy cost of shortcuts to adiabatic expansions or compressions of a harmonic oscillator, the power strokes of a quantum Otto engine. Difficulties to identify the cost stem from the interplay between different parts of the total system (the primary system —the particle— and the control system) and definitions of work (exclusive and inclusive). While attention is usually paid to the inclusive work of the microscopic primary system, we identify the energy cost as the exclusive work of the total system, which, for a clear-cut scale disparity between a microscopic primary system and a macroscopic control system, coincides with the exclusive work for the control system alone. We redefine the “engine efficiency” taking into account this cost. Our working horse model is an engine based on an ion in a Paul trap with power strokes designed via shortcuts to adiabaticity. Opposite to the paradigm of slow-cycle reversible engines with vanishing power and maximal efficiency, this fast-cycle engine increases the microscopic power at the price of a vanishing efficiency. The Paul trap fixes the gauge for the primary system, resulting in a counterintuitive evolution of its inclusive power and internal energy. Conditions for which inclusive power of the primary system and exclusive power control system are proportional are found