626 research outputs found
An exact master equation for the system-reservoir dynamics under the strong coupling regime and non-Markovian dynamics
In this paper we present a method to derive an exact master equation for a
bosonic system coupled to a set of other bosonic systems, which plays the role
of the reservoir, under the strong coupling regime, i.e., without resorting to
either the rotating-wave or secular approximations. Working with phase-space
distribution functions, we verify that the dynamics are separated in the
evolution of its center, which follows classical mechanics, and its shape,
which becomes distorted. This is the generalization of a result by Glauber, who
stated that coherent states remain coherent under certain circumstances,
specifically when the rotating-wave approximation and a zero-temperature
reservoir are used. We show that the counter-rotating terms generate
fluctuations that distort the vacuum state, much the same as thermal
fluctuations.Finally, we discuss conditions for non-Markovian dynamics
Morphology, biology and pesticide tolerance of Chelotogenes ornatus (Acai: Cheyletidae).
This paper reports on the morphology, biology and pesticide tolerance of Cheletogenes ornatus, the most common predator of Pinnaspis aspidistrae in the region of Juazeiro- Bahia- Brazil. Some differences between C. ornatus from Brazil and redescriptions in the literature are mentioned in this paper. At 28 +ou- 5oC the duration of the life cycle was 40.6 and 31 days for female gametes and male gametes respectively. Females had 2 nymphal stages while the only male obtained in the laboratory had a single nymphal stage. C. ornatus reproduced by thelytokous parthenogenesis, and male gametes were seldom produced. The peak was ca. 0.8 crawler of P. aspidistrae/gemale gamete/day. The least harmful chemicals to adult females of C. ornatus were methyl parathion, malathion, cyhexatin, zineb and sulfur. Those chemicals caused less than 10% mortality of female gametes at he recommended rates on citrus. COncurrently, the first 2 chemicals caused over 70% mortality of crawlers of P. aspidistrae in the laboratory at the recommended rates
From ergodicity to Stark many-body localization in spin chains with single-ion anisotropy
The principles of ergodicity and thermalization constitute the foundation of
statistical mechanics, positing that a many-body system progressively loses its
local information as it evolves. Nevertheless, these principles can be
disrupted when thermalization dynamics lead to the conservation of local
information, as observed in the phenomenon known as many-body localization.
Quantum spin chains provide a fundamental platform for exploring the dynamics
of closed interacting quantum many-body systems. This study explores the
dynamics of a spin chain with within the Majumdar-Ghosh model,
incorporating a non-uniform magnetic field and single-ion anisotropy. Through
the use of exact numerical diagonalization, we unveil that a nearly
constant-gradient magnetic field suppress thermalization, a phenomenon termed
Stark many-body localization (SMBL), previously observed in chains.
Furthermore, our findings reveal that the sole presence of single-ion
anisotropy is sufficient to prevent thermalization in the system.
Interestingly, when the magnitudes of the magnetic field and anisotropy are
comparable, they compete, favoring delocalization. Despite the potential
hindrance of SMBL by single-ion anisotropy in this scenario, it introduces an
alternative mechanism for localization. Our interpretation, considering local
energetic constraints and resonances between degenerate eigenstates, not only
provides insights into SMBL but also opens avenues for future experimental
investigations into the enriched phenomenology of disordered free localized
systems
Ornithological bibliography of the Azores
Only scientific publications up to 1980 are included in this bibliography. Other old narrations containing information on Azorean ornithology are being assembled for future publication. Certain unpublished works will also be dealt with. The part for consultation has been arranged in three sections. The first presents a numbered list of papers and books in chronological
order up to 1980. Last minute alterations obliged us to eliminate some items and to use «bis» for repeated numbers in some cases. The second section consists of the list of papers under their authors in alphabetical order. Finally, the third section consists of an index of the scientific names of the species cited.
The index contains three types of entries:
- The names of the genera, in capital letters, followed by the specific and subspecific names, which lead to their numbers in the chronological list. The latter are accompanied by the relevant page numbers, in brackets. - The names of the species, in small letters in bold-faced type,
lead to the names of the genera. - The names of the subspecies, in normal small letters, lead to the genera and species. Example: Fringilla coelebs moreletti entered under FRINGILLA, coelebs and moreletti, with the
bibliographical references only under the complete name. Papers of Nºs. 17, 41, 72, 74, 76 have not been consulted by us; all other works are available in our library
Persisting quantum effects in the anisotropic Rabi model at thermal equilibrium
Quantum correlations and nonclassical states are at the heart of emerging
quantum technologies. Efforts to produce long-lived states of such quantum
resources are a subject of tireless pursuit. Among several platforms useful for
quantum technology, the mature quantum system of light-matter interactions
offers unprecedented advantages due to current on-chip nanofabrication,
efficient quantum control of its constituents, and its wide range of
operational regimes. Recently, a continuous transition between the
Jaynes-Cummings model and the Rabi model has been proposed by exploiting
anisotropies in their light-matter interactions, known as the anisotropic
quantum Rabi model. In this work, we study the long-lived quantum correlations
and nonclassical states generated in the anisotropic Rabi model and how these
indeed persist even at thermal equilibrium. To achieve this, we thoroughly
analyze several quantumness quantifiers, where the long-lived quantum state is
obtained from a dressed master equation that is valid for all coupling regimes
and with the steady state ensured to be the canonical Gibbs state. Furthermore,
we demonstrate a stark distinction between virtual excitations produced beyond
the strong coupling regime and the quantumness quantifiers once the
light-matter interaction has been switched off. This raises the key question
about the nature of the equilibrium quantum features generated in the
anisotropic quantum Rabi model and paves the way for future experimental
investigations, without the need for challenging ground-state cooling
Explorations for natural enemies of the cassava green mite in Brazil.
The cassava green mite (Mononychellus tanajoa (Bondar)) is today one of the most important pests of cassava in Africa. Explorations for efficient natural enemies of that pest were initiated in Brazil in the beginning of 1988 through an agreement between Africa-wide Biological Control Programm/International Institute of Tropical Agriculture and the Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA). The work consists basically of two major components. The first refers to the identification of areas with consistently low infestations of the mite and determination of the natural enemies associated with it. The second refers to field estimations of the efficiency of the natural enemies found. Until now, the most widespread enemies detected were the predaceous Amblyseius idaeus (Denmark and Muma) and Amblyseius limonicus Garman and McGregor s.l., the former in drier and the latter in more humid places
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