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This paper reports progress on the NIST effort to develop a new calculable capacitor, focusing on improvement of the guard electrode motion control as well as issues associated with the overall electrode alignment. Design of a multi-wavelength Fabry-Perot interferometer which may facilitate testing the calculable capacitor in air is also discussed.
A new Fabry-Perot interferometer for state-of-the-art displacement measurements is demonstrated. Two different methods for measuring the change in the length of an optical cavity are employed and compared. The “radio frequency” method employs no optical reference and allows us to measure the length of a prototype Fabry-Perot cavity to an rms statistical uncertainty of 560 pm, corresponding to a fractional...
We describe a Fabry-Perot interferometer system designed to measure the variable spacing between two electrodes in the new NIST calculable capacitor. Using narrow-linewidth telecom lasers, we span a frequency interval of 18 GHz, and achieve a fractional uncertainty of δv/Δ ~1.7 × 10-8 without an optical frequency standard. In the near future we will introduce a rubidium optical standard and frequency...
A new calculable capacitor with an operating range of 0.1 pF is being developed at NIST. Reduced uncertainty for displacement measurements, enabled by employing tunable laser based Fabry-Perot interferometers, will allow a considerably more compact design, minimizing errors from mechanical sources. Using 3-D electric field simulations, we have also estimated errors resulting from mechanical imperfections.
We demonstrate sensitive optical readout of the motion of a wavelength-scale mechanical resonator via its scattering within a high-finesse optical cavity. Static calibration, dynamic monitoring and feedback cooling are presented.
We show that polarization-entangled photon pairs can be obtained deterministically from a semiconductor quantum dot by optically tuning the fine-structure split exciton states into degeneracy.
A scanning Fabry-Perot cavity is used to measure the photoluminescence of InAs/GaAs self-assembled quantum dots with linewidths as low as 1 GHz. This cavity is subsequently locked to the dot emission using PI control.
A new calculable capacitor with an operating range of 0.1 pF is being developed at NIST. Incorporation of Fabry-Perot displacement metrology employing a tunable laser will allow a continuous set of electrode displacements, as opposed to the discrete set in the current implementation. In addition, the reduced uncertainty in the displacement measurement will allow a considerably more compact apparatus,...
In this paper, we present a domain-specific interface definition language (IDL) and its compiler, dedicated to the development of pervasive computing applications. Our IDL provides declarative support for concisely characterizing a pervasive computing environment. This description is (1) to be used by programmers as a high-level reference to develop applications that coordinate entities of the target...
We analyze the performance of CPU-bound network servers and demonstrate experimentally that the degradation in the performance of these servers under high-concurrency workloads is largely due to inefficient use of the hardware caches. We then describe an approach to speeding up event-driven network servers by optimizing their use of the L2 CPU cache in the context of the TUX Web server, known for...
Software architectures must frequently evolve to cope with changing requirements, and this evolution often implies integrating new concerns. Unfortunately, existing architecture description languages provide little or no support for this kind of evolution. The software architect must modify the architecture manually, which risks introducing inconsistencies. In previous work, we have proposed the TranSATframework,...
Software architecture is a key concept in the design of a complex system. An architecture models the structure and behavior of the system, including the software elements and the relationships between them. While architectures were originally specified informally, recent years have seen the creation of a number of Architecture Description Languages (ADLs) [4]. ADLs are designed around the dimensions...
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