A universal adiabatic quantum query algorithm

Quantum query complexity is known to be characterized by the so-called quantum adversary bound. While this result has been proved in the standard discrete-time model of quantum computation, it also holds for continuous-time (or Hamiltonian-based) quantum computation, due to a known equivalence between these two query complexity models. In this work, we revisit this result by providing a direct proof in the continuous-time model. One originality of our proof is that it draws new connections between the adversary bound, a modern technique of theoretical computer science, and early theorems of quantum mechanics. Indeed, the proof of the lower bound is based on Ehrenfest's theorem, while the upper bound relies on the adiabatic theorem, as it goes by constructing a universal adiabatic quantum query algorithm. Another originality is that we use for the first time in the context of quantum computation a version of the adiabatic theorem that does not require a spectral gap.Comment: 22 pages, compared to v1, includes a rigorous proof of the correctness of the algorithm based on a version of the adiabatic theorem that does not require a spectral ga

Creep of Bulk C--S--H: Insights from Molecular Dynamics Simulations

Understanding the physical origin of creep in calcium--silicate--hydrate (C--S--H) is of primary importance, both for fundamental and practical interest. Here, we present a new method, based on molecular dynamics simulation, allowing us to simulate the long-term visco-elastic deformations of C--S--H. Under a given shear stress, C--S--H features a gradually increasing shear strain, which follows a logarithmic law. The computed creep modulus is found to be independent of the shear stress applied and is in excellent agreement with nanoindentation measurements, as extrapolated to zero porosity

Large-eddy simulation of the flow in a lid-driven cubical cavity

Large-eddy simulations of the turbulent flow in a lid-driven cubical cavity have been carried out at a Reynolds number of 12000 using spectral element methods. Two distinct subgrid-scales models, namely a dynamic Smagorinsky model and a dynamic mixed model, have been both implemented and used to perform long-lasting simulations required by the relevant time scales of the flow. All filtering levels make use of explicit filters applied in the physical space (on an element-by-element approach) and spectral (modal) spaces. The two subgrid-scales models are validated and compared to available experimental and numerical reference results, showing very good agreement. Specific features of lid-driven cavity flow in the turbulent regime, such as inhomogeneity of turbulence, turbulence production near the downstream corner eddy, small-scales localization and helical properties are investigated and discussed in the large-eddy simulation framework. Time histories of quantities such as the total energy, total turbulent kinetic energy or helicity exhibit different evolutions but only after a relatively long transient period. However, the average values remain extremely close

Isothermal remanent magnetization and the spin dimensionality of spin glasses

The isothermal remanent magnetization is used to investigate dynamical magnetic properties of spatially three dimensional spin glasses with different spin dimensionality (Ising, XY, Heisenberg). The isothermal remanent magnetization is recorded vs. temperature after intermittent application of a weak magnetic field at a constant temperature $T_h$. We observe that in the case of the Heisenberg spin glasses, the equilibrated spin structure and the direction of the excess moment are recovered at $T_h$. The isothermal remanent magnetization thus reflects the directional character of the Dzyaloshinsky-Moriya interaction present in Heisenberg systems.Comment: tPHL2e style; 7 page, 3 figure

Quantum Communication Uplink to a 3U CubeSat: Feasibility & Design

Satellites are the efficient way to achieve global scale quantum communication (Q.Com) because unavoidable losses restrict fiber based Q.Com to a few hundred kilometers. We demonstrate the feasibility of establishing a Q.Com uplink with a tiny 3U CubeSat (measuring just 10X10X32 cm^3 ) using commercial off-the-shelf components, the majority of which have space heritage. We demonstrate how to leverage the latest advancements in nano-satellite body-pointing to show that our 4kg CubeSat can provide performance comparable to much larger 600kg satellite missions. A comprehensive link budget and simulation was performed to calculate the secure key rates. We discuss design choices and trade-offs to maximize the key rate while minimizing the cost and development needed. Our detailed design and feasibility study can be readily used as a template for global scale Q.Com.Comment: 24 pages, 9 figures, 2 tables. Fixed tables and figure

Usporedba ALADIN i IFS Modela brzine vjetra preko Jadrana

The wind output from atmospheric models is instrumental in forcing the oceanic models. Here we consider the wind output from the ALADIN and IFS models and compare it with the results of scatterometer and altimeter estimates of wind speed over the Adriatic Sea, as well as with the field data from 18 meteorological stations and a gas rig platform. A five-year period from 2008 to 2012 is considered in the comparison. Our principal conclusion is that, overall, both atmospheric models, when compared to the altimeter data, give very similar statistical results, with a scatter index of 0.33 and 0.35 for IFS and ALADIN respectively. More specifically, the ALADIN appears to be better in the Northern Adriatic whereas the IFS seems superior in the Southern Adriatic. A possible explanation of this difference could be that the higher spatial resolution of ALADIN is crucial in resolving the bora wind impact over the Northern Adriatic.Vjetar dobiven atmosferskim modelima je instrumentalan u prisiljavanju oceanskog modela. U ovom radu razmotrit će se vjetra dobiven Aladin i IFS modelima te će se usporediti s rezultatima skat -erometrijske i altimetrijske procjene brzine vjetra iznad Jadranskog mora, kao i s 18 meteoroloških postaja i plinske platforme u razdoblju 2008-2012. Glavni zaključak je da oba atmosferska modela, u usporedbi s podacima altimetrije, daju vrlo slične statističke rezultate, s indeksom raspršenja 0,33 za IFS i 0,35 za ALADIN. Čini se da ALADIN daje bolje rezultate za sjeverni Jadran, a IFS za južni Jadran. Moguće objašnjenje te razlike može biti veća prostorna rezolucija ALADIN-a koja je presudna u rješavanju utjecaja bure na sjevernom Jadranu

Control of small inhibitory RNA levels and RNA interference by doxycycline induced activation of a minimal RNA polymerase III promoter

RNA interference (RNAi) mediated by expression of short hairpin RNAs (shRNAs) is a powerful tool for efficiently suppressing target genes. The approach allows studies of the function of individual genes and may also be applied to human therapy. However, in many instances regulation of RNAi by administration of a small inducer molecule will be required. To date, the development of appropriate regulatory systems has been hampered by the few possibilities for modification within RNA polymerase III promoters capable of driving efficient expression of shRNAs. We have developed an inducible minimal RNA polymerase III promoter that is activated by a novel recombinant transactivator in the presence of doxycycline (Dox). The recombinant transactivator and the engineered promoter together form a system permitting regulation of RNAi by Dox-induced expression of shRNAs. Regulated RNAi was mediated by one single lentiviral vector, blocked the expression of green fluorescent protein (GFP) in a GFP-expressing HEK 293T derived cell line and suppressed endogenous p53 in wild-type HEK 293T, MCF-7 and A549 cells. RNA interference was induced in a dose- and time-dependent manner by administration of Dox, silenced the expression of both target genes by 90% and was in particular reversible after withdrawal of Dox