ABSTRACT
We propose a mechanism of long-range coherent coupling between nuclear spin qubits in semiconductor-heterojunction quantum information processing devices. The coupling is via localized donor electrons which interact with the two-dimensional electron gas. An effective interaction Hamiltonian is derived and the coupling strength is evaluated. We also discuss mechanisms of decoherence and consider gate control of the interaction between qubits. The resulting quantum computing scheme retains all the control and measurement aspects of earlier approaches, but allows qubit spacing at distances of the order of 100 nm, attainable with the present-day semiconductor device technologies.
ABSTRACT
Most cases of sialolithiasis of the submandibular duct are resolved by an intraoral surgical approach. This case is unique in that by virtue of the sialolith's proximity to the hilum of the gland, it was more prudent to perform an excision of the entire gland through an extraoral approach.
Subject(s)
Salivary Gland Calculi/diagnosis , Submandibular Gland Diseases/diagnosis , Adult , Chronic Disease , Female , Fibrosis , Humans , Salivary Gland Calculi/surgery , Sialadenitis/diagnosis , Sialadenitis/surgery , Submandibular Gland/pathology , Submandibular Gland Diseases/surgeryABSTRACT
It has been experimentally established in numerous cases that precipitation of monodispersed colloids from homogeneous solutions is a complex process. Specifically, it was found that in many systems nuclei, produced rapidly in a supersaturated solution, grow to nanosize primary particles (singlets), which then coagulate to form much larger final colloids in a process dominated by irreversible capture of these singlets. This paper describes a kinetic model that explains the formation of dispersions of narrow size distribution in such systems. Numerical simulations of the kinetic equations, with experimental model parameter values, are reported. The model was tested for a system involving formation of uniform spherical gold particles by reduction of auric chloride in aqueous solutions. The calculated average size, the width of the particle size distribution, and the time scale of the process agreed reasonably well with the experimental values. Copyright 1999 Academic Press.
