1,854 research outputs found
Ultra-Strong Optomechanics Incorporating the Dynamical Casimir Effect
We propose a superconducting circuit comprising a dc-SQUID with mechanically
compliant arm embedded in a coplanar microwave cavity that realizes an
optomechanical system with a degenerate or non-degenerate parametric
interaction generated via the dynamical Casimir effect. For experimentally
feasible parameters, this setup is capable of reaching the single-photon,
ultra-strong coupling regime, while simultaneously possessing a parametric
coupling strength approaching the renormalized cavity frequency. This opens up
the possibility of observing the interplay between these two fundamental
nonlinearities at the single-photon level.Comment: 7 pages, 1 figure, 1 tabl
How Vocabulary is Learned
Vocabulary learning requires two basic conditions – repetition (quantity of meetings with words) and good quality mental processing of the meetings. Other factors also affect vocabulary learning. For example, learners may differ greatly in their motivation to engage in learning, and words may differ greatly in their learning burden. However, without quantity and quality of processing, learning cannot occur. The greater the number of repetitions, the more likely learning is to occur. The deeper and more thoughtful the quality of processing, the more likely learning is to occur. This paper explains quantity and quality, and shows how teachers and learners can increase the quantity and quality of their processing of vocabulary, thus increasing their vocabulary size
Iterative solutions to the steady state density matrix for optomechanical systems
We present a sparse matrix permutation from graph theory that gives stable
incomplete Lower-Upper (LU) preconditioners necessary for iterative solutions
to the steady state density matrix for quantum optomechanical systems. This
reordering is efficient, adding little overhead to the computation, and results
in a marked reduction in both memory and runtime requirements compared to other
solution methods, with performance gains increasing with system size. Either of
these benchmarks can be tuned via the preconditioner accuracy and solution
tolerance. This reordering optimizes the condition number of the approximate
inverse, and is the only method found to be stable at large Hilbert space
dimensions. This allows for steady state solutions to otherwise intractable
quantum optomechanical systems.Comment: 10 pages, 5 figure
Pragmatic Divestment of KC-135 Navigators in the Special Operations Air Refueling Mission
In the late 1990s, the Air Force eliminated over 200 KC-135 navigators, leaving 50 remaining for the aircraft\u27s most complex Special Operations Air Refueling (SOAR) mission. As the Air Force unveils the KC-46 Pegasus, this mission will continue but without a position for the navigator. Instead, navigators will undergo divestment as the SOAR mission transfers to the KC-46. Current plans indicate navigators will not only remain as the KC-46 arrives, but inbound navigators will continue arriving until 2018. This thesis applies the Delphi method, a process eliciting analysis anonymously from a panel of experts, in order to examine the elements affecting KC-135 navigator divestment and offer a more effective, comprehensive solution. Ultimately, the panel of experts arrived at conclusions supporting the hypothesis that navigator divestment and SOAR transition should occur sooner, rather than later, in order to secure a future for current navigators, ensure responsible development of Air Force officers, and enable the complex SOAR mission to endure. In order to best achieve these results, the experts recommended halting all inbound navigator assignments, reassigning navigators at a conservative rate over the next several years, and beginning a SOAR transition program to replace the tanker navigator with a third pilot concept
Quantum analysis of a nonlinear microwave cavity-embedded dc SQUID displacement detector
We carry out a quantum analysis of a dc SQUID mechanical displacement
detector, comprising a SQUID with mechanically compliant loop segment, which is
embedded in a microwave transmission line resonator. The SQUID is approximated
as a nonlinear, current dependent inductance, inducing an external flux
tunable, nonlinear Duffing self-interaction term in the microwave resonator
mode equation. Motion of the compliant SQUID loop segment is transduced
inductively through changes in the external flux threading SQUID loop, giving a
ponderomotive, radiation pressure type coupling between the microwave and
mechanical resonator modes. Expressions are derived for the detector signal
response and noise, and it is found that a soft-spring Duffing self-interaction
enables a closer approach to the displacement detection standard quantum limit,
as well as cooling closer to the ground state
Quantum Analysis of a Nonlinear Microwave Cavity-Embedded dc SQUID Displacement Detector
We carry out a quantum analysis of a dc superconducting quantum interference device (SQUID) mechanical displacement detector, comprising a SQUID with mechanically compliant loop segment, which is embedded in a microwave transmission line resonator. The SQUID is approximated as a nonlinear current-dependent inductance, inducing an external flux tunable nonlinear Duffing self-interaction term in the microwave resonator mode equation. Motion of the compliant SQUID loop segment is transduced inductively through changes in the external flux threading SQUID loop, giving a ponderomotive radiation pressure-type coupling between the microwave and mechanical resonator modes. Expressions are derived for the detector signal response and noise, and it is found that a soft-spring Duffing self-interaction enables a closer approach to the displacement detection standard quantum limit, as well as cooling closer to the ground state
Non-equilibrium Landauer Transport Model for Hawking radiation from a Black Hole
We propose that the Hawking radiation energy and entropy flow rates from a
black hole can be viewed as a one-dimensional (1D), non-equilibrium Landauer
transport process. Support for this viewpoint comes from previous calculations
invoking conformal symmetry in the near-horizon region, which give radiation
rates that are identical to those of a single 1D quantum channel connected to a
thermal reservoir at the Hawking temperature. The Landauer approach shows in a
direct way the particle statistics independence of the energy and entropy
fluxes of a black hole radiating into vacuum, as well as one near thermal
equilibrium with its environment. As an application of the Landauer approach,
we show that Hawking radiation gives a net entropy production that is 50%
larger than that obtained assuming standard three-dimensional emission into
vacuum.Comment: 14 pages, 2 figures, published versio
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