Scaling behaviour in random non-commutative geometries

Random non-commutative geometries are a novel approach to taking a non-perturbative path integral over geometries. They were introduced in arxiv.org/abs/1510.01377, where a first examination was performed. During this examination we found that some geometries show indications of a phase transition. In this article we explore this phase transition further for geometries of type $(1,1)$, $(2,0)$, and $(1,3)$. We determine the pseudo critical points of these geometries and explore how some of the observables scale with the system size. We also undertake first steps towards understanding the critical behaviour through correlations and in determining critical exponents of the system.Comment: 16 pages, 16 figures (v2: updated after review

Results and Perspectives of the Auger Engineering Radio Array

The Auger Engineering Radio Array (AERA) is an extension of the Pierre Auger Cosmic-Ray Observatory. It is used to detect radio emission from extensive air showers with energies beyond $10^{17}~$eV in the $30 - 80~$MHz frequency band. After three phases of deployment, AERA now consists of more than 150 autonomous radio stations with different spacings, covering an area of about $17~$km$^2$. It is located at the same site as other Auger low-energy detector extensions enabling combinations with various other measurement techniques. The radio array allows different technical schemes to be explored as well as cross-calibration of our measurements with the established baseline detectors of the Auger Observatory. We report on the most recent technological developments and give an overview of the experimental results obtained with AERA. In particular, we will present the measurement of the radiation energy, i.e., the amount of energy that is emitted by the air shower in the form of radio emission, and its dependence on the cosmic-ray energy by comparing with the measurement of the the well-calibrated Auger surface detector. Furthermore, we outline the relevance of this result for the absolute calibration of the energy scale of cosmic-ray observatories.Comment: To be published in the Proceedings of the ARENA2016 conference, Groningen, The Netherland

Semantic Squirrels

We argue that data should be acquired now. Every day that goes by data is lost. We propose Semantic Squirrels, a community-enabled low technology solution to data acquisition to achieve this data acquisition, while other more difficult problems wait to be resolved

Observing observatories: web observatories should use linked data

Web Observatories are a major international scientific collaboration concerned with data sources of a heterogeneous nature, and often quite large. Of course, they are not the first such collaboration; the Web itself was born as a response to a similar scientific endeavor. It is therefore appropriate to look at other col-laborative activities, and try to learn and use the lessons they have learnt.We argue that Web Observatories should build in interoperability using current best practices right from the start. We also argue that Linked Data is a best practice, and can provide the basis for a research environment that will deliver the vision of a large group of cooperating Observatories, sharing data and re-search results to the benefit of all. In addition, we argue that the activity should not start with a major standardization process, but should grow around appro-priate standards as required

ARIANNA: Measurement of cosmic rays with a radio neutrino detector in Antarctica

The ARIANNA detector aims to detect neutrinos with energies above \SI{e16}{eV} by instrumenting 0.5 Teratons of ice with a surface array of a thousand independent radio detector stations in Antarctica. The Antarctic ice is transparent to the radio signals caused by the Askaryan effect which allows for a cost-effective instrumentation of large volumes. Several pilot stations are currently operating successfully at the Moore's Bay site (Ross Ice Shelf) and at the South Pole. As the ARIANNA detector stations are positioned at the surface, the more abundant cosmic-ray air showers are also measured and serve as a direct way to prove the capabilities of the detector. We will present measured cosmic rays and will show how the incoming direction, polarization and electric field of the cosmic-ray pulse can be reconstructed from single detector stations comprising 4 upward and 4 downward facing LPDA antennas.Comment: Proceedings of the 8th International Conference on Acoustic and Radio EeV Neutrino Detection Activities, ARENA 201

Boundary of Quantum Evolution under Decoherence

Relaxation effects impose fundamental limitations on our ability to coherently control quantum mechanical phenomena. In this letter, we establish physical limits on how closely can a quantum mechanical system be steered to a desired target state in the presence of relaxation. In particular, we explicitly compute the maximum coherence or polarization that can be transferred between coupled nuclear spins in the presence of very general decoherence mechanisms that include cross-correlated relaxation. We give analytical expressions for the control laws (pulse sequences) which achieve these physical limits and provide supporting experimental evidence. Exploitation of cross-correlation effects has recently led to the development of powerful methods in NMR spectroscopy to study very large biomolecules in solution. We demonstrate with experiments that the optimal pulse sequences provide significant gains over these state of the art methods, opening new avenues for spectroscopy of much larger proteins. Surprisingly, in spite of very large relaxation rates, optimal control can transfer coherence without any loss when cross-correlated relaxation rates are tuned to auto-correlated relaxation rates