Preparing projected entangled pair states on a quantum computer

We present a quantum algorithm to prepare injective PEPS on a quantum computer, a class of open tensor networks representing quantum states. The run-time of our algorithm scales polynomially with the inverse of the minimum condition number of the PEPS projectors and, essentially, with the inverse of the spectral gap of the PEPS' parent Hamiltonian.Comment: 5 pages, 1 figure. To be published in Physical Review Letters. Removed heuristics, refined run-time boun

NFAT5 genes are part of the osmotic regulatory system in Atlantic salmon (Salmo salar)

Acknowledgements This study was supported by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC, BB/H008063/1), UK to DGH and SAM. Funding also came from Research Council Norway for project number 241016 for DGH and EJ. This work was carried out as part of a PhD thesis funded by the Marine Alliance of Science and Technology Scotland (MASTS).Peer reviewedPublisher PD

The emission line near 1319 A in solar and stellar spectra

An emission line near 1319 A is one of the strongest unidentified lines in the ultraviolet spectra of cool dwarf stars. In most line lists it is identified as a transition in N I, although its intensity would then be anomalous and the observed wavelength does not fit precisely that expected for N I. The line is also observed in cool giant stars. The measured wavelength of the line in stellar spectra is 1318.94 (+,- 0.01) A. Observations of giant stars provide further evidence that this line is not due to N I. It is proposed that this line is a decay from a previously unknown level in S I, which lies above the first ionization limit. This is identified with the 3d singlet D (odd parity) term. The previous tentative assignment of this term to the S I line at 1309.3 A then needs to be revised. The 1309.3 A line has been identified here for the first time in an astrophysical source. The singlet D (odd parity) level could, in principle, be populated by collisions from nearby autoionizing levels that have large number-densities, through population by di-electronic capture. Spin-orbit interaction with the autoionizing triplet D (odd parity) term might also lead to di-electronic capture into the singlet D (odd parity) level. A line at 1309.87 A observed in cool giant stars is identified as a transition in P II, pumped by the O I resonance lines.Comment: 9 pages, 3 figures, to be published in Monthly Notices of the Royal Astronomical Societ

Ionic N-Phenylpyridinium Tetracatenar Mesogens : N -phenylpyridinium tetracatenar mesogens: Competing driving forces in mesophase formation and unprecedented difference in phase stabilisation within a homologous series

Ionic, tetracatenar liquid crystals containing an N-phenylpyridinum core are described; many of these compounds display a SmA phase, something extremely rare in tetracatenar materials. The competing forces driving mesophase formation lead to an unprecedented difference in phase stabilities for SmA and Colh phases

Spectral aerosol extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300– 700 nm wavelength range, the spectral aerosol extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs) agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including nonabsorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx measurements are expected to help identify the presence of ambient brown carbon due to its 300 nm lower wavelength limit compared to measurements limited to longer UV and visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström exponents). Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation

Electric dipole moments and disalignment of interstellar dust grains

The degree to which interstellar grains align with respect to the interstellar magnetic field depends on disaligning as well as aligning mechanisms. For decades, it was assumed that disalignment was due primarily to the random angular impulses a grain receives when colliding with gas-phase atoms. Recently, a new disalignment mechanism has been considered, which may be very potent for a grain that has a time-varying electric dipole moment and drifts across the magnetic field. We provide quantitative estimates of the disalignment times for silicate grains with size > approximately 0.1 micron. These appear to be shorter than the time-scale for alignment by radiative torques, unless the grains contain superparamagnetic inclusions.Comment: 12 pages, 9 figures, submitted to MNRA