Random Control over Quantum Open Systems

Parametric fluctuations or stochastic signals are introduced into the control pulse sequence to investigate the feasibility of random control over quantum open systems. In a large parameter error region, the out-of-order control pulses work as well as the regular pulses for dynamical decoupling and dissipation suppression. Calculations and analysis are based on a non-perturbative control approach allowed by an exact quantum-state-diffusion equation. When the average frequency and duration of the pulse sequence take proper values, the random control sequence is robust, fault- tolerant, and insensitive to pulse strength deviations and interpulse temporal separation in the quasi-periodic sequence. This relaxes the operational requirements placed on quantum control experiments to a great deal.Comment: 7 pages, 6 firgure

Young people’s experiences using electric powered indoor-outdoor wheelchairs (EPIOCs): Potential for enhancing users’ development?

Purpose: To examine the experiences of severely physically disabled young people using electric powered indoor/outdoor chairs (EPIOCs). Methods: A priori interview questions examined young people’s functioning with EPIOCs, pain and discomfort with EPIOC use and accidents or injuries resulting from EPIOC use. Eighteen young people (13 males and 5 females) aged 10 -18 (mean 15) years were interviewed by telephone using a qualitative framework approach. Participants were interviewed 10 -19 (mean 14.5) months after delivery of the chair. Diagnoses included muscular dystrophy (n = 10), cerebral palsy (n = 5), and ‘other’ (n =3). Results: Many children reported positive functioning following EPIOC use, including increased independence and social activities like wheelchair football. However, EPIOC use was also associated with pain and discomfort, as well as perceived lack of safety, and minor accidents. Most young people and their families were fairly satisfied with the service and provision of their wheelchairs. Conclusions: The findings suggest that disabled children’s development may benefit from the use of electric powered indoor/outdoor wheelchairs, although the advantages may come at certain costs to young people’s perceived and real safety. Recommendations to powered wheelchair providers include the demonstrated need for additional driving training as these young people mature

Synchronization of groups of coupled oscillators with sparse connections

Synchronization of groups of coupled oscillators with sparse connections are explored. It is found that different topologies of intergroup couplings may lead to different synchronizability. In the strong-coupling limit, an analytical treatment and criterion is proposed to judge the synchronization between communities of oscillators, and an optimal connection scheme for the group synchronization is given. By varying the intergroup and intragroup coupling strengths, different synchronous phases, i.e., the unsynchronized state, intragroup synchronization, intergroup synchronization, and global synchronization are revealed. The present discussions and results can be applied to study the pattern formation and synchronization of coupled spatiotemporal systems

Derivation of the transverse force on a moving vortex in a superfluid

We describe an exact derivation of the total nondissipative transverse force acting on a quantized vortex moving in a uniform background. The derivation is valid for neutral boson or fermion superfluids, provided the order parameter is a complex scalar quantity. The force is determined by the one-particle density matrix far away from the vortex core, and is found to be the Magnus force proportional to the superfluid density.Comment: Latex, 6 page

Structure of Stochastic Dynamics near Fixed Points

We analyze the structure of stochastic dynamics near either a stable or unstable fixed point, where force can be approximated by linearization. We find that a cost function that determines a Boltzmann-like stationary distribution can always be defined near it. Such a stationary distribution does not need to satisfy the usual detailed balance condition, but might have instead a divergence-free probability current. In the linear case the force can be split into two parts, one of which gives detailed balance with the diffusive motion, while the other induces cyclic motion on surfaces of constant cost function. Using the Jordan transformation for the force matrix, we find an explicit construction of the cost function. We discuss singularities of the transformation and their consequences for the stationary distribution. This Boltzmann-like distribution may be not unique, and nonlinear effects and boundary conditions may change the distribution and induce additional currents even in the neighborhood of a fixed point.Comment: 7 page

Tunneling of a Quantized Vortex: Roles of Pinning and Dissipation

We have performed a theoretical study of the effects of pinning potential and dissipation on vortex tunneling in superconductors. Analytical results are obtained in various limits relevant to experiment. In general we have found that pinning and dissipation tend to suppress the effect of the vortex velocity dependent part of the Magnus force on vortex tunneling.Comment: Latex, 12 page

Geometric phases in dressed state quantum computation

Geometric phases arise naturally in a variety of quantum systems with observable consequences. They also arise in quantum computations when dressed states are used in gating operations. Here we show how they arise in these gating operations and how one may take advantage of the dressed states producing them. Specifically, we show that that for a given, but arbitrary Hamiltonian, and at an arbitrary time {\tau}, there always exists a set of dressed states such that a given gate operation can be performed by the Hamiltonian up to a phase {\phi}. The phase is a sum of a dynamical phase and a geometric phase. We illustrate the new phase for several systems.Comment: 4 pages, 2 figure

Hydrographic Study of Peirce Island Wastewater Treatment Plant Effluent in the Piscataqua River of Portsmouth, New Hampshire: Report of Findings from the December 10 – 14, 2012 Study Period

In order to assist the New Hampshire Department of Environmental Services (NHDES) evaluate the impact of treated wastewater effluent from Peirce Island Wastewater Treatment Plant (WWTP) to the Lower Piscataqua River and Portsmouth Harbor a hydrographic dye study was conducted in December 2012 in Portsmouth, NH. Eight (8) shellfish cages with American oysters (Crassostrea virginica) and blue mussels (Mytilus edulis) were deployed both upstream and downstream of the Peirce Island WWTP in the Piscataqua River, Little Harbor, and the entrance of Little Bay. Eight (8) mini CTDs that monitor conductivity/salinity, temperature, and depth, and six (6) moored fluorometers, which measure dye tagged effluent from the Peirce Island WWTP were attached to the subsurface cages. A fifty (50) gallon mixture of Rhodamine WT dye and distilled water was injected into WWTP on December 11, 2012 for a half tidal cycle (approximately 12.4 hours). Additionally, boat tracking fluorometers connected with a mobile geographic information system (GIS) were used to measure dye levels on the surface in situ and in real time. Microbiological analyses of fecal coliform (FC), male-specific coliphage (MSC), Norovirus (NoV) genogroup I (GI) and genogroup II (GII), and Adenovirus (AdV) were conducted on WWTP influent and effluent composite samples collected with automated samplers to determine the WWTP efficiency in reducing indicator bacteria and viruses. Microbiological sampling and testing of oysters and mussels from the eight (8) sentinel cages was conducted to assess the impact of WWTP effluent on shellfish growing areas and growing area classifications. Prior to conducting the study, the assumption was that the FDA’s recommended minimum dilution of 1000:1was not applicable in this situation because the recommended dilution is based on a WWTP having at least secondary treatment. The microbiological findings in shellfish samples, wastewater samples from the Peirce Island WWTP, and the results of the dye study, confirm that a minimum of 1,000:1 dilution with respect to Peirce Island WWTP is currently not applicable for this WWTP. The FDA and NHDES recommend continued MSC testing of wastewater samples from the WWTP before and after the WWTP upgrade. The FDA and NHDES recommend a future field study after the WWTP upgrade in order to delineate the 1,000:1 dilution zone