Microwave-induced excess quasiparticles in superconducting resonators measured through correlated conductivity fluctuations

We have measured the number of quasiparticles and their lifetime in aluminium superconducting microwave resonators. The number of excess quasiparticles below 160 mK decreases from 72 to 17 $\mu$m$^{-3}$ with a 6 dB decrease of the microwave power. The quasiparticle lifetime increases accordingly from 1.4 to 3.5 ms. These properties of the superconductor were measured through the spectrum of correlated fluctuations in the quasiparticle system and condensate of the superconductor, which show up in the resonator amplitude and phase respectively. Because uncorrelated noise sources vanish, fluctuations in the superconductor can be studied with a sensitivity close to the vacuum noise

Number fluctuations of sparse quasiparticles in a superconductor

We have directly measured quasiparticle number fluctuations in a thin film superconducting Al resonator in thermal equilibrium. The spectrum of these fluctuations provides a measure of both the density and the lifetime of the quasiparticles. We observe that the quasiparticle density decreases exponentially with decreasing temperature, as theoretically predicted, but saturates below 160 mK to 25-55 per cubic micron. We show that this saturation is consistent with the measured saturation in the quasiparticle lifetime, which also explains similar observations in qubit decoherence times

Evaluation of Mobility Modes on Lunar Exploration Traverses - Marius Hills, Copernicus Peaks, and Hadley Apennines Missions

Energy and time costs of lunar walking or riding traverses, and scientific tasks on J-type missions, and capabilities of A7L suits and life support system

Photon noise limited radiation detection with lens-antenna coupled Microwave Kinetic Inductance Detectors

Microwave Kinetic Inductance Detectors (MKIDs) have shown great potential for sub-mm instrumentation because of the high scalability of the technology. Here we demonstrate for the first time in the sub-mm band (0.1...2 mm) a photon noise limited performance of a small antenna coupled MKID detector array and we describe the relation between photon noise and MKID intrinsic generation-recombination noise. Additionally we use the observed photon noise to measure the optical efficiency of detectors to be 0.8+-0.2.Comment: The following article has been submitted to AP

Integrated Filterbank for DESHIMA: A Submillimeter Imaging Spectrograph Based on Superconducting Resonators

An integrated filterbank (IFB) in combination with microwave kinetic inductance detectors (MKIDs), both based on superconducting resonators, could be used to make broadband submillimeter imaging spectrographs that are compact and flexible. In order to investigate the possibility of adopting an IFB configuration for DESHIMA (Delft SRON High-redshift Mapper), we study the basic properties of a coplanar-waveguide-based IFB using electromagnetic simulation. We show that a coupling efficiency greater than 1/2 can be achieved if transmission losses are negligible. We arrive at a practical design for a 9 pixel x 920 color 3 dimensional imaging device that fits on a 4 inch wafer, which instantaneously covers multiple submillimeter telluric windows with a dispersion of f/df = 1000.Comment: 6 pages, 4 figures, submitted to LTD-14 / Journal of Low Temperature Physic

Interactive Effects of Inducible Defense and Resource Availability on Phlorotannins in the North Atlantic Brown Alga \u3ci\u3eFucus vesiculosus\u3c/i\u3e

Research seeking to explain the ecological role of polyphenolics (phlorotannins) in plants and brown algae has largely focused on 2 alternative concepts, the carbon/nutrient (C/N) balance and the inducible defense models. We tested the hierarchy of effects of both models on phlorotannin production in the brown alga Fucus vesiculosus (Fucales) by simultaneously manipulating the N environment and simulating herbivory for 2 oceanic (high and low intertidal) and estuarine populations. We measured phlorotannin levels in algae under control, grazed, N-enriched, and grazed + N-enriched treatments with time (0 to 14 d) throughout the year to determine onset and duration of the response. We found greater support for the inducible defense model; generally, both grazed and grazed + N- enriched fronds had significantly higher phlorotannin concentrations than control thalli. When we found an inducible response, it was rapid (within 3 d) and relatively long term (\u3e2 wk). However, the induced response was minimal for both oceanic populations during March, perhaps due to fixed-C limitation, and was absent for the estuarine and high intertidal populations during June, the period of peak phlorotannins at both sites. Although N enrichment resulted in depressed concentrations of phlorotannins only for the estuarine population, we did measure a significant negative correlation between tissue N and phenolics for the oceanic population, as predicted by the C/N balance model. Thus, while the inducible defense response takes preeminence over resource availability effects (C/N balance hypothesis), this study revealed that phlorotannin production is likely controlled by a complex interaction of environmental, developmental and defense-related factors, emphasizing the applicability of both models in marine systems

A First Principles Theory of Nuclear Magnetic Resonance J-Coupling in solid-state systems

A method to calculate NMR J-coupling constants from first principles in extended systems is presented. It is based on density functional theory and is formulated within a planewave-pseudopotential framework. The all-electron properties are recovered using the projector augmented wave approach. The method is validated by comparison with existing quantum chemical calculations of solution-state systems and with experimental data. The approach has been applied to verify measured J-coupling in a silicophosphate structure, Si5O(PO4)6Comment: 9 page