Continuously observing a dynamically decoupled spin-1 quantum gas

We continuously observe dynamical decoupling in a spin-1 quantum gas using a weak optical measurement of spin precession. Continuous dynamical decoupling aims to dramatically modify the character and energy spectrum of spin states to render them insensitive to parasitic fluctuations. Continuous observation measures this new spectrum in a single-preparation of the quantum gas. The measured time-series contains seven tones, which spectrogram analysis parses as splittings, coherences, and coupling strengths between the decoupled states in real-time. With this we locate a regime where a transition between two states is decoupled from magnetic field instabilities up to fourth order, complementary to the parallel work at higher fields by Trypogeorgos et al. (arXiv:1706.07876). The decoupled microscale quantum gas offers magnetic sensitivity in a tunable band, persistent over many milliseconds: the length scales, frequencies, and durations relevant to many applications, including sensing biomagnetic phenomena such as neural spike trains.Comment: 5+ pages, 4 figures, 1 table; revised citation of Trypogeorgos et al. (2017

Abelian homotopy Dijkgraaf-Witten theory

We construct a version of Dijkgraaf-Witten theory based on a compact abelian Lie group within the formalism of Turaev's homotopy quantum field theory. As an application we show that the 2+1-dimensional theory based on U(1) classifies lens spaces up to homotopy type.Comment: 23 pages, 1 figur

Inlet spillage drag tests and numerical flow-field analysis at subsonic and transonic speeds of a 1/8-scale, two-dimensional, external-compression, variable-geometry, supersonic inlet configuration

Accurate spillage drag and pressure data are presented for a realistic supersonic inlet configuration. Results are compared with predictions from a finite-differencing, inviscid analysis computer procedure. The analytical technique shows good promise for the evaluation of inlet drag, but necessary refinements were identified. A detailed description of the analytical procedure is contained in the Appendix

A Possible Late Time Λ\LambdaCDM-like Background Cosmology in Relativistic MOND Theory

In the framework of Relativistic MOND theory (TeVeS), we show that a late time background $\Lambda$CDM cosmology can be attained by choosing a specific $F(\mu)$ that also meets the requirement for the existence of Newtonian and MOND limits. We investigate the dynamics of the scalar field $\phi$ under our chosen $F(\mu)$ and show that the "slow roll" regime of $\phi$ corresponds to a dynamical attractor, where the whole system reduces to $\Lambda$CDM cosmology.Comment: Major revisions made; Matching the version to be published in IJMP

Suspended liminality: Vacillating affects in cyberbullying/research

This paper develops a concept of liminal hotspots in the context of i) a secondary analysis of a cyberbullying case involving a group of school children from a Danish school, and ii) an altered auto-ethnography in which the authors ‘entangle’ their own experiences with the case analysis. These two sources are used to build an account of a liminal hotspot conceived as an occasion of troubled and suspended transformative transition in which a liminal phase is extended and remains unresolved. The altered auto-ethnography is used to explore the affectivity at play in liminal hotspots, and this liminal affectivity is characterised in terms of volatility, vacillation, suggestibility and paradox

High Rayleigh number convection with double diffusive fingers

An electrodeposition cell is used to sustain a destabilizing concentration difference of copper ions in aqueous solution between the top and bottom boundaries of the cell. The resulting convecting motion is analogous to Rayleigh-B\'enard convection at high Prandtl numbers. In addition, a stabilizing temperature gradient is imposed across the cell. Even for thermal buoyancy two orders of magnitude smaller than chemical buoyancy, the presence of the weak stabilizing gradient has a profound effect on the convection pattern. Double diffusive fingers appear in all cases. The size of these fingers and the flow velocities are independent of the height of the cell, but they depend on the ion concentration difference between top and bottom boundaries as well as on the imposed temperature gradient. The scaling of the mass transport is compatible with previous results on double diffusive convection

An extreme, blueshifted iron line profile in the Narrow Line Seyfert 1 PG 1402+261; an edge-on accretion disk or highly ionized absorption?

We report on a short XMM-Newton observation of the radio-quiet Narrow Line Seyfert 1 PG 1402+261. The EPIC X-ray spectrum of PG 1402+261 shows a strong excess of counts between 6-9 keV in the rest frame. This feature can be modeled by an unusually strong (equivalent width 2 keV) and very broad (FWHM velocity of 110000 km/s) iron K-shell emission line. The line centroid energy at 7.3 keV appears blue-shifted with respect to the iron Kalpha emission band between 6.4-6.97 keV, while the blue-wing of the line extends to 9 keV in the quasar rest frame. The line profile can be fitted by reflection from the inner accretion disk, but an inclination angle of >60 deg is required to model the extreme blue-wing of the line. Furthermore the extreme strength of the line requires a geometry whereby the hard X-ray emission from PG 1402+261 above 2 keV is dominated by the pure-reflection component from the disk, while little or none of the direct hard power-law is observed. Alternatively the spectrum above 2 keV may instead be explained by an ionized absorber, if the column density is sufficiently high (N_H > 3 x 10^23 cm^-2) and if the matter is ionized enough to produce a deep (tau~1) iron K-shell absorption edge at 9 keV. This absorber could originate in a large column density, high velocity outflow, perhaps similar to those which appear to be observed in several other high accretion rate AGN. Further observations, especially at higher spectral resolution, are required to distinguish between the accretion disk reflection or outflow scenarios.Comment: Accepted for publication in ApJ (18 pages, 5 figures, 1 table