1,416 research outputs found
Tunable ohmic environment using Josephson junction chains
We propose a scheme to implement a tunable, wide frequency-band dissipative
environment using a double chain of Josephson junctions. The two parallel
chains consist of identical SQUIDs, with magnetic-flux tunable inductance,
coupled to each other at each node via a capacitance much larger than the
junction capacitance. Thanks to this capacitive coupling, the system sustains
electromagnetic modes with a wide frequency dispersion. The internal quality
factor of the modes is maintained as high as possible, and the damping is
introduced by a uniform coupling of the modes to a transmission line, itself
connected to an amplification and readout circuit. For sufficiently long
chains, containing several thousands of junctions, the resulting admittance is
a smooth function versus frequency in the microwave domain, and its effective
dissipation can be continuously monitored by recording the emitted radiation in
the transmission line. We show that by varying in-situ the SQUIDs' inductance,
the double chain can operate as tunable ohmic resistor in a frequency band
spanning up to one GHz, with a resistance that can be swept through values
comparable to the resistance quantum R_q = (h/4e^2) ~ 6.5 k{\Omega}. We argue
that the circuit complexity is within reach using current Josephson junction
technology.Comment: 11 pages, 9 figure
Learning more effectively from experience
Developing the capacity for individuals to learn effectively from their experiences is an important part of building the knowledge and skills in organizations to do good adaptive management. This paper reviews some of the research from cognitive psychology and phenomenography to present a way of thinking about learning to assist individuals to make better use of their personal experiences to develop understanding of environmental systems. We suggest that adaptive expertise (an individual’s ability to deal flexibly with new situations) is particularly relevant for environmental researchers and practitioners. To develop adaptive expertise, individuals need to: (1) vary and reflect on their experiences and become adept at seeking out and taking different perspectives; and (2) become proficient at making balanced judgements about how or if an experience will change their current perspective or working representation of a social, economic, and biophysical system by applying principles of “good thinking.” Such principles include those that assist individuals to be open to the possibility of changing their current way of thinking (e.g., the disposition to be adventurous) and those that reduce the likelihood of making erroneous interpretations (e.g., the disposition to be intellectually careful). An example of applying some of the principles to assist individuals develop their understanding of a dynamically complex wetland system (the Macquarie Marshes in Australia) is provided. The broader implications of individual learning are also discussed in relation to organizational learning, the role of experiential knowledge for conservation, and for achieving greater awareness of the need for ecologically sustainable activity
Inductively shunted transmon qubit with tunable transverse and longitudinal coupling
We present the design of an inductively shunted transmon qubit with
flux-tunable coupling to an embedded harmonic mode. This circuit construction
offers the possibility to flux-choose between pure transverse and pure
longitudinal coupling, that is coupling to the or degree
of freedom of the qubit. While transverse coupling is the coupling type that is
most commonly used for superconducting qubits, the inherently different
longitudinal coupling has some remarkable advantages both for readout and for
the scalability of a circuit. Being able to choose between both kinds of
coupling in the same circuit provides the flexibility to use one for coupling
to the next qubit and one for readout, or vice versa. We provide a detailed
analysis of the system's behavior using realistic parameters, along with a
proposal for the physical implementation of a prototype device.Comment: 14 pages, 14 figure
Holographic optical trapping Raman micro-spectroscopy for non-invasive measurement and manipulation of live cells
We present a new approach for combining holographic optical tweezers with confocal Raman spectroscopy. Multiple laser foci, generated using a liquid-crystal spatial light modulator, are individually used for both optical trapping and excitation of spontaneous Raman spectroscopy from trapped objects. Raman scattering from each laser focus is spatially filtered using reflective apertures on a digital micro-mirror device, which can be reconfigured with flexible patterns at video rate. We discuss operation of the instrument, and performance and viability considerations for biological measurements. We then demonstrate the capability of the instrument for fast, flexible, and interactive manipulation with molecular measurement of interacting live cell systems
Implementation of low-loss superinductances for quantum circuits
The simultaneous suppression of charge fluctuations and offsets is crucial
for preserving quantum coherence in devices exploiting large quantum
fluctuations of the superconducting phase. This requires an environment with
both extremely low DC and high RF impedance. Such an environment is provided by
a superinductance, defined as a zero DC resistance inductance whose impedance
exceeds the resistance quantum at
frequencies of interest (1 - 10 GHz). In addition, the superinductance must
have as little dissipation as possible, and possess a self-resonant frequency
well above frequencies of interest. The kinetic inductance of an array of
Josephson junctions is an ideal candidate to implement the superinductance
provided its phase slip rate is sufficiently low. We successfully implemented
such an array using large Josephson junctions (), and measured
internal losses less than 20 ppm, self-resonant frequencies greater than 10
GHz, and phase slip rates less than 1 mHz
International Conference of Territorial Intelligence, Alba Iulia 2006. Vol.2, Proceedings of caENTI - Coordination Action of the European Network of Territorial Intelligence (deliverable 12 of caENTI, project funded under FP6 research program of the European Union), Aeternitas, Alba Iulia, 2007
GIRARDOT J.-J., PASCARU M., ILEANA I., 2007A'.International audienceThese acts gather the communications of the International Conference of Territorial Intelligence that took place in ALBA IULIA in Romania, from September, the 20th to September, the 22nd 2006. This conference was the fourth conference of territorial intelligence, but the conference of ALBA IULIA is the first one that took place in the CAENTI, Coordination Action of the European Network of Territorial Intelligence, framework. Consequently, it has a particular organization. A part is devoted to the presentation of the CAENTI research activities and of their prospects. The CAENTI specific communications are published in another volume
- …