936 research outputs found
The Role of Temperature in the occurrence of some Zeno Phenomena
Temperature can be responsible for strengthening effective couplings between
quantum states, determining a hierarchy of interactions, and making it possible
to establish such dynamical regimes known as Zeno dynamics, wherein a strong
coupling can hinder the effects of a weak one. The relevant physical mechanisms
which connect the structure of a thermal state with the appearance of special
dynamical regimes are analyzed in depth
The Destruction of UNESCO World Heritage Sites Aleppo and Palmyra in Syria Due to Civil War: Accessioning and Cataloging the Satellite and Drone Imagery into a Museum Collection
This Museum Studies capstone will discuss the civil war inside Syria, and the destruction of UNESCO World Heritage Sites Aleppo and Palmyra. This paper will examine the historical importance of these sites, and the drone and satellite imagery data used to confirm the destruction. This paper will argue that for full preservation of these cultural heritage sites that this imagery data should be accessioned into a museum collection with the use of professionally-trained registrars. This paper will explore this idea further by arguing that this imagery data collected by companies and governments should be handed over with full copyright to the museums operating at these two sites inside Syria
Perturbative Treatment of the Evolution Operator Associated with Raman Couplings
A novel perturbative treatment of the time evolution operator of a quantum system is applied to the model describing a Raman-driven trapped ion in order to obtain a suitable 'effective model'. It is shown that the associated effective Hamiltonian describes the system dynamics up to a certain transformation which may be interpreted as a 'dynamical dressing' of the effective model
Stimulated Raman adiabatic passage in an open quantum system: Master equation approach
A master equation approach to the study of environmental effects in the
adiabatic population transfer in three-state systems is presented. A systematic
comparison with the non-Hermitian Hamiltonian approach [N. V. Vitanov and S.
Stenholm, Phys. Rev. A {\bf 56}, 1463 (1997)] shows that in the weak coupling
limit the two treatments lead to essentially the same results. Instead, in the
strong damping limit the predictions are quite different: in particular the
counterintuitive sequences in the STIRAP scheme turn out to be much more
efficient than expected before. This point is explained in terms of quantum
Zeno dynamics.Comment: 11 pages, 4 figure
Population trapping due to cavity losses
In population trapping the occupation of a decaying quantum level keeps a
constant non-zero value. We show that an atom-cavity system interacting with an
environment characterized by a non-flat spectrum, in the non-Markovian limit,
exhibits such a behavior, effectively realizing the preservation of
nonclassical states against dissipation. Our results allow to understand the
role of cavity losses in hybrid solid state systems and pave the way to the
proper description of leakage in the recently developed cavity quantum
electrodynamic systems.Comment: 4 pages, 3 figures, version accepted for publication on Phys. Rev.
Influence of dissipation on the extraction of quantum states via repeated measurements
A quantum system put in interaction with another one that is repeatedly
measured is subject to a non-unitary dynamics, through which it is possible to
extract subspaces. This key idea has been exploited to propose schemes aimed at
the generation of pure quantum states (purification). All such schemes have so
far been considered in the ideal situations of isolated systems. In this paper,
we analyze the influence of non-negligible interactions with environment during
the extraction process, with the scope of investigating the possibility of
purifying the state of a system in spite of the sources of dissipation. A
general framework is presented and a paradigmatic example consisting of two
interacting spins immersed in a bosonic bath is studied. The effectiveness of
the purification scheme is discussed in terms of purity for different values of
the relevant parameters and in connection with the bath temperature.Comment: 10 pages, 3 figure
Fluctuation characteristics of the TCV snowflake divertor measured with high speed visible imaging
Tangentially viewing fast camera footage of the low-field side snowflake
minus divertor in TCV is analysed across a four point scan in which the
proximity of the two X-points is varied systematically. The motion of
structures observed in the post- processed movie shows two distinct regions of
the camera frame exhibiting differing patterns. One type of motion in the outer
scrape-off layer remains present throughout the scan whilst the other, apparent
in the inner scrape-off layer between the two nulls, becomes increasingly
significant as the X-points contract towards one another. The spatial structure
of the fluctuations in both regions is shown to conform to the equilibrium
magnetic field. When the X-point gap is wide the fluctuations measured in the
region between the X-points show a similar structure to the fluctuations
observed above the null region, remaining coherent for multiple toroidal turns
of the magnetic field and indicating a physical connectivity of the
fluctuations between the upstream and downstream regions. When the X-point gap
is small the fluctuations in the inner scrape-off layer between the nulls are
decorrelated from fluctuations upstream, indicating local production of
filamentary structures. The motion of filaments in the inter-null region
differs, with filaments showing a dominantly poloidal motion along magnetic
flux surfaces when the X-point gap is large, compared to a dominantly radial
motion across flux-surfaces when the gap is small. This demonstrates an
enhancement to cross-field tranport between the nulls of the TCV low-field-side
snowflake minus when the gap between the nulls is small.Comment: Accepted for publication in Plasma Physics and Controlled Fusio
Tripartite thermal correlations in an inhomogeneous spin-star system
We exploit the tripartite negativity to study the thermal correlations in a
tripartite system, that is the three outer spins interacting with the central
one in a spin-star system. We analyze the dependence of such correlations on
the homogeneity of the interactions, starting from the case where central-outer
spin interactions are identical and then focusing on the case where the three
coupling constants are different. We single out some important differences
between the negativity and the concurrence.Comment: 8 pages, 9 figure
INTEGRATED 3D SURVEY FOR THE DOCUMENTATION AND VISUALIZATION OF A ROCK-CUT UNDERGROUND BUILT HERITAGE
Abstract. The research presented here is part of an on-going research focused on the 3D documentation of rock-cut Underground Built Heritage with a complex morphology and characterised by narrow spaces, the Hypogeum of Calaforno (province of Ragusa, Sicily). It is one of the most interesting prehistoric monuments in Sicily in terms of size and unique rock-cut architecture. Various digital techniques have been tested over the years on the site, to represent its spatiality, such as Laser Scanner and Structure from Motion. The proposed methodological approach for the knowledge and the documentation of this archaeological site is based on an interdisciplinary approach involving archaeological and engineering disciplines. This paper focuses on the use of expeditious techniques such as iMMS (indoor Mobile Mapping Systems) based on SLAM (Simultaneous Localization and Mapping) and on the comparison of different surveying equipment in order to verify data quality and accuracy, as well as the inherent advantages of using one technology over another in relation to the characteristics of the site. Through the global verification of TLS and SLAM model reliability, we maintain that such research can contribute to enriching the protocols surrounding the archaeological investigation of sites characterized by complex morphology, irregular surfaces, narrow spaces, specific chromatic features, scarce or total lack of lighting, and physical obstacles
LOW COST TECHNIQUES FOR THE DIGITAL SURVEY OF A MINOAN ARCHITECTURE IN THE ARCHEOLOGICAL SITE OF PHAISTOS (CRETE)
Abstract. The paper shows the results of an experimentation on the use of low cost tools such as action cameras for the photogrammetric surveying of relevant archaeological sites characterized by the presence of narrow and complex rooms. The archaeological site chosen for this experimentation is the South-Western Quarter, also known as Quartiere Levi, of the Minoan Palace of Phaistos (Crete), one of only two cases of buildings surviving up to the third floor in the Aegean world. The research foresaw the setting up of a pipeline aimed at obtaining a complete scaled, photorealistic and navigable 3D model, with a considerable economy in terms of work time and number of photographs. For this purpose, many efforts have been paid on solving all the issues related to the complexity of the site and on comparing the performances of traditional (Canon EOS 70D) and action (GoPro Black Hero 6) cameras as well as of two of the current most used software in the field
- …