5,746 research outputs found
Interference in Bohmian Mechanics with Complex Action
In recent years, intensive effort has gone into developing numerical tools
for exact quantum mechanical calculations that are based on Bohmian mechanics.
As part of this effort we have recently developed as alternative formulation of
Bohmian mechanics in which the quantum action, S, is taken to be complex [JCP
{125}, 231103 (2006)]. In the alternative formulation there is a significant
reduction in the magnitude of the quantum force as compared with the
conventional Bohmian formulation, at the price of propagating complex
trajectories. In this paper we show that Bohmian mechanics with complex action
is able to overcome the main computational limitation of conventional Bohmian
methods -- the propagation of wavefunctions once nodes set in. In the vicinity
of nodes, the quantum force in conventional Bohmian formulations exhibits rapid
oscillations that pose severe difficulties for existing numerical schemes. We
show that within complex Bohmian mechanics, multiple complex initial conditions
can lead to the same real final position, allowing for the description of nodes
as a sum of the contribution from two or more crossing trajectories. The idea
is illustrated on the reflection amplitude from a one-dimensional Eckart
barrier. We believe that trajectory crossing, although in contradiction to the
conventional Bohmian trajectory interpretation, provides an important new tool
for dealing with the nodal problem in Bohmian methods
Fat/water separation imaging shows fatty deposition in areas of chronic left ventricular myocardial infarction
Feasibility study of an Integrated Program for Aerospace vehicle Design (IPAD). Volume 4: IPAD system design
The computing system design of IPAD is described and the requirements which form the basis for the system design are discussed. The system is presented in terms of a functional design description and technical design specifications. The functional design specifications give the detailed description of the system design using top-down structured programming methodology. Human behavioral characteristics, which specify the system design at the user interface, security considerations, and standards for system design, implementation, and maintenance are also part of the technical design specifications. Detailed specifications of the two most common computing system types in use by the major aerospace companies which could support the IPAD system design are presented. The report of a study to investigate migration of IPAD software between the two candidate 3rd generation host computing systems and from these systems to a 4th generation system is included
A scalable optical detection scheme for matter wave interferometry
Imaging of surface adsorbed molecules is investigated as a novel detection
method for matter wave interferometry with fluorescent particles. Mechanically
magnified fluorescence imaging turns out to be an excellent tool for recording
quantum interference patterns. It has a good sensitivity and yields patterns of
high visibility. The spatial resolution of this technique is only determined by
the Talbot gratings and can exceed the optical resolution limit by an order of
magnitude. A unique advantage of this approach is its scalability: for certain
classes of nano-sized objects, the detection sensitivity will even increase
significantly with increasing size of the particle.Comment: 10 pages, 4 figure
AI Insurance: How Liability Insurance Can Drive the Responsible Adoption of Artificial Intelligence in Health Care
Despite enthusiasm about the potential to apply artificial intelligence (AI) to medicine and health care delivery, adoption remains tepid, even for the most compelling technologies. In this article, the authors focus on one set of challenges to AI adoption: those related to liability. Well-designed AI liability insurance can mitigate predictable liability risks and uncertainties in a way that is aligned with the interests of health care’s main stakeholders, including patients, physicians, and health care organization leadership. A market for AI insurance will encourage the use of high-quality AI, because insurers will be most keen to underwrite those products that are demonstrably safe and effective. As such, well-designed AI insurance products are likely to reduce the uncertainty associated with liability risk for both manufacturers — including developers of software as a medical device — and clinician users and thereby increase innovation, competition, adoption, and trust in beneficial technological advances
Observation of slow light in the noise spectrum of a vertical external cavity surface emitting laser
The role of coherent population oscillations is evidenced in the noise
spectrum of an ultra-low noise lasers. This effect is isolated in the intensity
noise spectrum of an optimized single-frequency vertical external cavity
surface emitting laser. The coherent population oscillations induced by the
lasing mode manifest themselves through their associated dispersion that leads
to slow light effects probed by the spontaneous emission present in the
non-lasing side modes.Comment: accepted for publication in Phys. Rev. Let
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