Resolution in rotation measurements

The limiting resolution in optical interferometry is set by the number of photons used, with the functional dependence determined by the state of light that is prepared. We consider the problem of measuring the rotation of a beam of light about an optical axis and show how the limiting resolution depends on the total number of quanta of orbital angular momentum carried by the light beam.Comment: 14 page

Vacuum Friction

We know that in empty space there is no preferred state of rest. This is true both in special relativity but also in Newtonian mechanics with its associated Galilean relativity. It comes as something of a surprise, therefore, to discover the existence a friction force associated with spontaneous emission. he resolution of this paradox relies on a central idea from special relativity even though our derivation of it is non-relativistic. We examine the possibility that the physics underlying this effect might be explored in an ion trap, via the observation of a superposition of different mass states.Comment: 8 pages, 2 figures. Published in Journal of Modern Optics on 14 September 2017. Version 2 with a corrected typo on page

Rabi Oscillations in Systems with Small Anharmonicity

When a two-level quantum system is irradiated with a microwave signal, in resonance with the energy difference between the levels, it starts Rabi oscillation between those states. If there are other states close, in energy, to the first two, the Rabi signal will also induce transition to those. Here, we study the probability of transition to the third state, in a three-level system, while a Rabi oscillation between the first two states is performed. We investigate the effect of pulse shaping on the probability and suggest methods for optimizing pulse shapes to reduce transition probability.Comment: 7 pages, 7 figure

Clinical users' perspective on telemonitoring of patients with long term conditions: Understood through concepts of Giddens's structuration theory & consequence of modernity

This is the post-print version of the article - Copyright @ 2010 IOS.This study involves conducting focus group discussions with clinical users (nurses and technicians) prior to the launch of telehealth service in Nottingham, UK, to elicit their initial perceptions about the service. It describes the findings from preliminary phase of otherwise a larger longitudinal study. Using Giddens’s concepts from structuration theory and con-sequence of modernity, we were able to acknowledge trust and sense of security as two very salient aspects that govern adop-tion of new technological innovation. Unattended, these as-pects contribute to arousal of conflict and contradiction within a system. In order for successful telehealth implementa-tions in health care setting, providers of the service, need to focus on ways in which clinical users’ trust can be gained and sense of security can be promoted while using the telehealth service and technology.Funding was obained from MATCH (Multidisciplinary Assessment of Technologies Centre for Healthcare)

Satellite applications to electric-utility communications needs

Significant changes in the Nation's electric power systems are expected to result from the integration of new technology, possible during the next decade. Digital communications for monitor and control, exclusive of protective relaying, are expected to double or triple current traffic. A nationwide estimate of 13 Mb/s traffic is projected. Of this total, 8 Mb/s is attributed to the bulk-power system as it is now being operated (4 Mb/s). This traffic could be accommodated by current communications satellites using 3- to 4.5-m-diameter ground terminals costing $35,000 to$70,000 each. The remaining 5-Mb/s traffic is attributed to new technology concepts integrated into the distribution system. Such traffic is not compatible with current satellite technology because it requires small, low-cost ground terminals. Therefore, a high effective isotropic radiated power satellite, such as the one being planned by NASA for the Land Mobile Satellite Service, is required

Full characterization of the quantum spiral bandwidth of entangled biphotons

Spontaneous parametric down-conversion has been shown to be a reliable source of entangled photons. Among the wide range of properties shown to be entangled, it is the orbital angular momentum that is the focus of our study. We investigate, in particular, the bi-photon state generated using a Gaussian pump beam. We derive an expression for the simultaneous correlations in the orbital angular momentum, l, and radial momentum, p, of the down-converted Laguerre-Gaussian beams. Our result allows us, for example, to calculate the spiral bandwidth with no restriction on the geometry of the beams: l, p, and the beam widths are all free parameters. Moreover, we show that, with the usual paraxial and collinear approximations, a fully analytic expression for the correlations can be derived

Retrodiction as a tool for micromaser field measurements

We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground state, for atoms that are initially prepared in the excited state. This provides the POM elements, which describe such sequences of measurements.Comment: 20 pages, 4(8) figure

Furlable antenna

An improved furlable antenna particularly suited for use in a celestial space environment is described. The antenna is characterized by an actuator comprising an elastomeric member of an annular configuration, an annular array of uniformly spaced antenna ribs rigidly affixed at the base ends to an actuator which enables it to be supported for pivotal displacement from a deployed configuration. The ribs are radially extended from the actuator to a furled configuration. The ribs are extended parallel to the axis of the actuator with flexible reflecting web affixed to the ribs, with angularly spaced bearing blocks

Light emission as a solar cell analysis technique

In order to determine if a solar cell would indeed emit usable light as expected, a gallium arsenide solar cell was forward biased and examined with an infrared viewer. The light emitted from the solar cell was not uniform, ever though the I-V curve of the solar cell displayed no defects