6,946 research outputs found
Switchable ultrastrong coupling in circuit QED
Superconducting quantum circuits possess the ingredients for quantum
information processing and for developing on-chip microwave quantum optics.
From the initial manipulation of few-level superconducting systems (qubits)
to their strong coupling to microwave resonators, the time has come to consider
the generation and characterization of propagating quantum microwaves. In this
paper, we design a key ingredient that will prove essential in the general
frame: a swtichable coupling between qubit(s) and transmission line(s) that can
work in the ultrastrong coupling regime, where the coupling strength approaches
the qubit transition frequency. We propose several setups where two or more
loops of Josephson junctions are directly connected to a closed (cavity) or
open transmission line. We demonstrate that the circuit induces a coupling that
can be modulated in strength and type. Given recent studies showing the
accessibility to the ultrastrong regime, we expect our ideas to have an
immediate impact in ongoing experiments
Deep Strong Coupling Regime of the Jaynes-Cummings model
We study the quantum dynamics of a two-level system interacting with a
quantized harmonic oscillator in the deep strong coupling regime (DSC) of the
Jaynes-Cummings model, that is, when the coupling strength g is comparable or
larger than the oscillator frequency w (g/w > 1). In this case, the
rotating-wave approximation cannot be applied or treated perturbatively in
general. We propose an intuitive and predictive physical frame to describe the
DSC regime where photon number wavepackets bounce back and forth along parity
chains of the Hilbert space, while producing collapse and revivals of the
initial population. We exemplify our physical frame with numerical and
analytical considerations in the qubit population, photon statistics, and
Wigner phase space.Comment: Published version, note change of title: DSC regime of the JC mode
Quantum Estimation Methods for Quantum Illumination
Quantum illumination consists in shining quantum light on a target region
immersed in a bright thermal bath, with the aim of detecting the presence of a
possible low-reflective object. If the signal is entangled with the receiver,
then a suitable choice of the measurement offers a gain with respect to the
optimal classical protocol employing coherent states. Here, we tackle this
detection problem by using quantum estimation techniques to measure the
reflectivity parameter of the object, showing an enhancement in the
signal-to-noise ratio up to 3 dB with respect to the classical case when
implementing only local measurements. Our approach employs the quantum Fisher
information to provide an upper bound for the error probability, supplies the
concrete estimator saturating the bound, and extends the quantum illumination
protocol to non-Gaussian states. As an example, we show how Schrodinger's cat
states may be used for quantum illumination.Comment: Published versio
The INTEGRAL-OMC Scientific Archive
The Optical Monitoring Camera (OMC) on-board the INTEGRAL satellite has, as
one of its scientific goals, the observation of a large number of variable
sources previously selected. After almost 6 years of operations, OMC has
monitored more than 100 000 sources of scientific interest. In this
contribution we present the OMC Scientific Archive
(http://sdc.laeff.inta.es/omc/) which has been developed to provide the
astronomical community with a quick access to the light curves generated by
this instrument.We describe the main characteristics of this archive, as well
as important aspects for the users: object types, temporal sampling of light
curves and photometric accuracy.Comment: 4 pages, 5 figures. "Highlights of Spanish Astrophysics V"
Proceedings of the VIII Scientific Meeting of the Spanish Astronomical
Society (SEA) held in Santander, July 7-11, 200
AVOCADO: A Virtual Observatory Census to Address Dwarfs Origins
Dwarf galaxies are by far the most abundant of all galaxy types, yet their
properties are still poorly understood -especially due to the observational
challenge that their intrinsic faintness represents. AVOCADO aims at
establishing firm conclusions on their formation and evolution by constructing
a homogeneous, multiwavelength dataset for a statistically significant sample
of several thousand nearby dwarfs (-18 < Mi < -14). Using public data and
Virtual Observatory tools, we have built GALEX+SDSS+2MASS spectral energy
distributions that are fitted by a library of single stellar population models.
Star formation rates, stellar masses, ages and metallicities are further
complemented with structural parameters that can be used to classify them
morphologically. This unique dataset, coupled with a detailed characterization
of each dwar's environment, allows for a fully comprehensive investigation of
their origins and to track the (potential) evolutionary paths between the
different dwarf types.Comment: 4 pages, 1 figure. To appear in the proceedings of IAU Symposium 277,
"Tracing the Ancestry of Galaxies on the Land of our Ancestors", Carignan,
Freeman, and Combes, ed
Fisheries wastewater as a sustainable media for the production of algae-based products
Colombian intensive fish production is concentrated mainly in the departments of the Andean Region, Amazon, and Orinoquía. These systems were characterized for being exploited mainly by family farming nuclei, which are dedicated exclusively to breeding and others with mixed systems. Currently, the sustainable development of this economic line depends on two factors: global warming and the consumption of resources (energy, fresh water, and protein). The rapid growth of this socio-economic line has led to the development of 3 critical restrictions: the demand for food for fish production, the high volume of fresh water needed and the high concentration of wastewater which must be disposed of safely. Sewage from closed fish farming systems has high levels of nitrogen and inorganic phosphorus dissolved in the systems. The primary responsibility for these high contents is the feed which contributes to the sustained increase in the concentration of organic waste and toxic compounds in aquatic systems. To make use of this wastewater, the use of these as a culture medium for microalgal production has been studied in order to generate metabolites of industrial interest from a low-cost culture medium. In this work, the necessary culture conditions for the biomass production of Scenedesmus obliquus, Chlorella vulgaris, Spirulina maxima, and Oscillatoria sp. in fish farming wastewater to produce pigments and total biomass are evaluated. The wastewater was obtained from an intensive fish farming company in El Zulia (Norte de Santander, Colombia). The medium was UV-sterilized (4 Lamps of 15W, 5 minutes). In order to optimize the production of biomass and pigments, the wastewater was adjusted with the addition of nitrogen, phosphorus, and carbon (K2HPO4 + NaNO3 + NaHCO3) According to the results, the residual water enriched with K2HPO4, NaNO3 and NaHCO3 presented the best culture conditions for obtaining carotenoids (in C. vulgaris and S. obliquus with values of 2.6 and 1.7% p/p respectively) and Phycobiliproteins in Spirulina maxima and Oscillatoria sp (10.9 and 11% p/p respectively). These results allow concluding that the residual water of fish systems is outlined as a suitable culture medium that can be used to produce metabolites of interest. Also, this culture medium must be enriched in order to increase the productivity of the system
Міхал Бобжинський: суспільно-політична діяльність
Розглянута суспільно-політична діяльність визначного представника краківської
історичної школи М. Бобжинського. Акцентовано увагу на зв’язку наукових поглядів
історика з його політичною практикою. Охарактеризовано дискусії, які досьогодні
точаться серед науковців щодо оцінки результатів його діяльності.Рассмотрена общественно-политическая деятельность выдающегося представителя краковской исторической школы М. Бобжинского. Акцентировано внимание на связи научных взглядов историка с его политической практикой. Охарактеризованы дискуссии, которые досегодня ведутся среди ученых относительно оценки результатов его деятельности.The socio-political activities of M. Bobzhynski – a prominent representative of the Krakow
historical school – are reviewed. Attention is given to the connection of the historian scholarly
views with his political practice. The discussions that until now are going on among scholars
in evaluating the results of his work are characterised
Tunable and Switchable Coupling Between Two Superconducting Resonators
We realize a device allowing for tunable and switchable coupling between two
superconducting resonators mediated by an artificial atom. For the latter, we
utilize a persistent current flux qubit. We characterize the tunable and
switchable coupling in frequency and time domain and find that the coupling
between the relevant modes can be varied in a controlled way. Specifically, the
coupling can be tuned by adjusting the flux through the qubit loop or by
saturating the qubit. Our time domain measurements allow us to find parameter
regimes for optimal switch performance with respect to qubit drive power and
the dynamic range of the resonator input power
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