455 research outputs found
Smart Cities and Cyber Security: Are We There Yet? A Comparative Study on the Role of Standards, Third Party Risk Management and Security Ownership
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Smart cities have brought a variety of benefits aiming to revolutionise people’s lives. Those include but are not limited to, increasing economic e ciency, reducing cost and decreasing environmental output. However, the smart city itself is still in its infancy. As it heavily relies on technologies, it opens up doors to cyber attackers and criminals, which can lead to significant losses. An outstanding problem concerns the social and organisational aspects of smart cities security resulting from competing interests of di event parties, high levels of interdependence, and social and political complexity. Our review shows that current standards and guidelines have not clearly defined roles and responsibilities of di erent parties. A common understanding of key security requirements is not shared between di erent parties. This research assessed the smart cities and their cyber security measures, with a particular focus on technical standards and the regulatory framework. It comprehensively reviewed 93 security standards and guidance. It then performed a comparative case study of Barcelona, Singapore and London smart cities on their governance models, security measures, technical standards and third party management. Based on the review and the case study, this research concluded on a recommended framework encompassing technical standards, governance input, regulatory framework and compliance assurance to ensure that security is observed at all layers of the
smart cities
Digital Flourishing: Conceptualizing and Assessing Positive Perceptions of Mediated Social Interactions
Recent research started to apply concepts of well-being to the context of computer mediated communication (e.g., social media, instant messaging). While much research investigates negative perceptions of mediated social interactions (e.g., “problematic” or “addictive” social media use), a multi-dimensional measure that taps into users? positive perceptions is sorely lacking. The present research therefore develops the first comprehensive measure of digital flourishing, defined as positive perceptions of mediated social interactions. Building on a qualitative pre-study that aided the construction of the Digital Flourishing Scale (DFS), Study 1 (N = 474) employed exploratory factor analysis to reveal five subdimensions of digital flourishing. The preregistered Study 2 (N = 438) confirmed these five dimensions, yielding five reliable items per subscale and initial construct validity with three psychological needs from self-determination theory (SDT; competence, autonomy, relatedness) which were used as an underlying well-being framework for the development of the DFS. The preregistered Study 3 generated further construct validity by directly relating DFS to well-being. The scale is relevant for researchers and practitioners alike to better understand how users perceive their mediated interactions to impact mental health and well-being
Universal homodyne tomography with a single local oscillator
We propose a general method for measuring an arbitrary observable of a
multimode electromagnetic field using homodyne detection with a single local
oscillator. In this method the local oscillator scans over all possible linear
combinations of the modes. The case of two modes is analyzed in detail and the
feasibility of the measurement is studied on the basis of Monte-Carlo
simulations. We also provide an application of this method in tomographic
testing of the GHZ state.Comment: 12 pages, 5 figures (8 eps files
Bichromatic atomic lens
We investigate the focusing of three-level atoms with a bichromatic standing wave laser field, using both classical and quantum treatments of the problem. We find that, for the appropriate ratio of detunings to Rabi frequencies, the atoms will experience a periodic potential which is close to harmonic across half an optical wavelength. The field thus becomes equivalent to a periodic array of microlenses, which could be utilized to deposit lines of atoms upon a substrate. We consider and compare two regimes, differentiated by the interaction time of the atoms in the optical field. The first case considered, the Raman-Nath regime, is analogous to the thin lens regime in classical optics. The second case treats the transverse atomic motion within the light field, and investigates the distribution of atoms upon a substrate placed within the field. We investigate the extent to which this case can be modeled classically
Talbot Oscillations and Periodic Focusing in a One-Dimensional Condensate
An exact theory for the density of a one-dimensional Bose-Einstein condensate
with hard core particle interactions is developed in second quantization and
applied to the scattering of the condensate by a spatially periodic impulse
potential. The boson problem is mapped onto a system of free fermions obeying
the Pauli exclusion principle to facilitate the calculation. The density
exhibits a spatial focusing of the probability density as well as a periodic
self-imaging in time, or Talbot effect. Furthermore, the transition from single
particle to many body effects can be measured by observing the decay of the
modulated condensate density pattern in time. The connection of these results
to classical and atom optical phase gratings is made explicit
Continuous optical loading of a Bose-Einstein Condensate
The continuous pumping of atoms into a Bose-Einstein condensate via
spontaneous emission from a thermal reservoir is analyzed. We consider the case
of atoms with a three-level scheme, in which one of the atomic
transitions has a very much shorter life-time than the other one. We found that
in such scenario the photon reabsorption in dense clouds can be considered
negligible. If in addition inelastic processes can be neglected, we find that
optical pumping can be used to continuously load and refill Bose-Einstein
condensates, i.e. provides a possible way to achieve a continuous atom laser.Comment: 12 pages, 8 figure
Least-squares inversion for density-matrix reconstruction
We propose a method for reconstruction of the density matrix from measurable
time-dependent (probability) distributions of physical quantities. The
applicability of the method based on least-squares inversion is - compared with
other methods - very universal. It can be used to reconstruct quantum states of
various systems, such as harmonic and and anharmonic oscillators including
molecular vibrations in vibronic transitions and damped motion. It also enables
one to take into account various specific features of experiments, such as
limited sets of data and data smearing owing to limited resolution. To
illustrate the method, we consider a Morse oscillator and give a comparison
with other state-reconstruction methods suggested recently.Comment: 16 pages, REVTeX, 6 PS figures include
High resolution amplitude and phase gratings in atom optics
An atom-field geometry is chosen in which an atomic beam traverses a field
interaction zone consisting of three fields, one having frequency propagating in the direction and the other two having
frequencies and propagating in the
- direction. For and , where and are positive integers and
is the pulse duration in the atomic rest frame, the atom-field interaction
results in the creation of atom amplitude and phase gratings having period . In this manner, one can use optical fields having
wavelength to produce atom gratings having periodicity much less
than .Comment: 11 pages, 14 figure
Self-homodyne tomography of a twin-beam state
A self-homodyne detection scheme is proposed to perform two-mode tomography
on a twin-beam state at the output of a nondegenerate optical parametric
amplifier. This scheme has been devised to improve the matching between the
local oscillator and the signal modes, which is the main limitation to the
overall quantum efficiency in conventional homodyning. The feasibility of the
measurement is analyzed on the basis of Monte-Carlo simulations, studying the
effect of non-unit quantum efficiency on detection of the correlation and the
total photon-number oscillations of the twin-beam state.Comment: 13 pages (two-column ReVTeX) including 21 postscript figures; to
appear on Phys. Rev.
Creating a low-dimensional quantum gas using dark states in an inelastic evanescent-wave mirror
We discuss an experimental scheme to create a low-dimensional gas of
ultracold atoms, based on inelastic bouncing on an evanescent-wave mirror.
Close to the turning point of the mirror, the atoms are transferred into an
optical dipole trap. This scheme can compress the phase-space density and can
ultimately yield an optically-driven atom laser. An important issue is the
suppression of photon scattering due to ``cross-talk'' between the mirror
potential and the trapping potential. We propose that for alkali atoms the
photon scattering rate can be suppressed by several orders of magnitude if the
atoms are decoupled from the evanescent-wave light. We discuss how such dark
states can be achieved by making use of circularly-polarized evanescent waves.Comment: 8 pages, 4 figure
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