1,891 research outputs found
Uncertainty-principle noise in vacuum-tunneling transducers
The fundamental sources of noise in a vacuum-tunneling probe used as an
electromechanical transducer to monitor the location of a test mass are
examined using a first-quantization formalism. We show that a tunneling
transducer enforces the Heisenberg uncertainty principle for the position and
momentum of a test mass monitored by the transducer through the presence of two
sources of noise: the shot noise of the tunneling current and the momentum
fluctuations transferred by the tunneling electrons to the test mass. We
analyze a number of cases including symmetric and asymmetric rectangular
potential barriers and a barrier in which there is a constant electric field.
Practical configurations for reaching the quantum limit in measurements of the
position of macroscopic bodies with such a class of transducers are studied
A scalable readout system for a superconducting adiabatic quantum optimization system
We have designed, fabricated and tested an XY-addressable readout system that
is specifically tailored for the reading of superconducting flux qubits in an
integrated circuit that could enable adiabatic quantum optimization. In such a
system, the flux qubits only need to be read at the end of an adiabatic
evolution when quantum mechanical tunneling has been suppressed, thus
simplifying many aspects of the readout process. The readout architecture for
an -qubit adiabatic quantum optimization system comprises hysteretic dc
SQUIDs and rf SQUID latches controlled by bias lines. The
latching elements are coupled to the qubits and the dc SQUIDs are then coupled
to the latching elements. This readout scheme provides two key advantages:
First, the latching elements provide exceptional flux sensitivity that
significantly exceeds what may be achieved by directly coupling the flux qubits
to the dc SQUIDs using a practical mutual inductance. Second, the states of the
latching elements are robust against the influence of ac currents generated by
the switching of the hysteretic dc SQUIDs, thus allowing one to interrogate the
latching elements repeatedly so as to mitigate the effects of stochastic
switching of the dc SQUIDs. We demonstrate that it is possible to achieve
single qubit read error rates of with this readout scheme. We have
characterized the system-level performance of a 128-qubit readout system and
have measured a readout error probability of in the presence
of optimal latching element bias conditions.Comment: Updated for clarity, final versio
A linear programming-based method for job shop scheduling
We present a decomposition heuristic for a large class of job shop scheduling problems. This heuristic utilizes information from the linear programming formulation of the associated optimal timing problem to solve subproblems, can be used for any objective function whose associated optimal timing problem can be expressed as a linear program (LP), and is particularly effective for objectives that include a component that is a function of individual operation
completion times. Using the proposed heuristic framework, we address job shop scheduling problems with a variety of objectives where intermediate holding costs need to be explicitly considered. In computational testing, we demonstrate the performance of our proposed solution approach
Misuse and Artifact in Factor Analytic Research
The theory of factor analysis has been developed for incorporating mathematical statistical theories such as the maximum likelihood method and asymptotic methods. However, there have been several instances of misuse while employing procedures for factor analysis studies. In several studies, factor analysis has been performed by deleting items exhibiting the ceiling effect or floor effect. The number of samples required for factor analysis is not well known. Kaiser-Guttman criterion cannot be applied for determining the number of factors. Furthermore, various studies have employed Scree Graphs and Parallel Analysis for the said purpose, but no definitive method exists for the same. Orthogonal rotation methods such as Varimax cannot be considered as a conclusive solution. However, Geomin has been considered as a better rotation method not only for simple structure but also for more complex factor configuration. Simple structure and bifactor structure are discussed in connection to factor rotation problem. Although there are various artifacts associated with the usage of factor analysis, this issue can be addressed by verifying factorial invariance through multi-group simultaneous analysis incorporated by SEM programs such as Mplus and R Package.因子分析の理論は、最尤法と漸近的方法のような数理統計学的理論を組み込んだ形で発展してきた。しかしながら、因子分析研究の手順にはまだ誤用がみられる。いくつかの研究において、天井効果や床効果を示す項目を削除して因子分析が行われている。因子分析に必要なサンプル数は明確ではない。因子の数を決定するためにKaiser-Guttman 基準は使うことはできない。そして、この目的でScree Graph とParallel Analysis を使用している研究は数多くあるが、そのための決定的な方法はない。Varimax のような直交回転は最終的な解と考えることはできない。しかしながら、Geomin は単純構造だけでなくより複雑な因子の布置に対しても優れた回転方法と考えられている。因子回転問題を考慮した単純構造とbifactor 構造について議論した。因子分析の使い方には多くのartifacts があるが、この問題は、Mplus やR Package などのSEMプログラムによって組み込まれた複数集団の同時分析によって因子的不変性を検証することによって対処することができる
Sign- and magnitude-tunable coupler for superconducting flux qubits
We experimentally confirm the functionality of a coupling element for
flux-based superconducting qubits, with a coupling strength whose sign and
magnitude can be tuned {\it in situ}. To measure the effective , the
groundstate of a coupled two-qubit system has been mapped as a function of the
local magnetic fields applied to each qubit. The state of the system is
determined by directly reading out the individual qubits while tunneling is
suppressed. These measurements demonstrate that can be tuned from
antiferromagnetic through zero to ferromagnetic.Comment: Updated text and figure
Challenging Perceptions of Disability through Performance Poetry Methods: The "Seen but Seldom Heard" Project.
This paper considers performance poetry as a method to explore lived experiences
of disability. We discuss how poetic inquiry used within a participatory arts-based
research framework can enable young people to collectively question society’s
attitudes and actions towards disability. Poetry will be considered as a means to
develop a more accessible and effective arena in which young people with direct
experience of disability can be empowered to develop new skills that enable them
to tell their own stories. Discussion of how this can challenge audiences to critically reflect upon their own perceptions of disability will also be developed
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