Linear Imperfections

This lecture gives an overview of the impacts on linear machine optics of machine imperfections due to incorrect field settings and misalignments. The effects of imperfections in dipole, quadrupole, and sextupole magnets are presented, along with beam observables and correction techniques that may be used to restore the nominal machine parameters. The main concepts of orbit correction are discussed in detail, because the principles underlying those techniques can be used for other corrections.Comment: 30 pages, contribution to the CAS - CERN Accelerator School: Beam Instrumentation, 2-15 June 2018, Tuusula, Finlan

Quantum pathology of static internal imperfections in flawed quantum computers

Even in the absence of external influences the operability of a quantum computer (QC) is not guaranteed because of the effects of residual one- and two-body imperfections. Here we investigate how these internal flaws affect the performance of a quantum controlled-NOT (CNOT) gate in an isolated flawed QC. First we find that the performance of the CNOT gate is considerably better when the two-body imperfections are strong. Secondly, we find that the largest source of error is due to a coherent shift rather than decoherence or dissipation. Our results suggest that the problem of internal imperfections should be given much more attention in designing scalable QC architectures

Dynamics of entanglement in quantum computers with imperfections

The dynamics of the pairwise entanglement in a qubit lattice in the presence of static imperfections exhibits different regimes. We show that there is a transition from a perturbative region, where the entanglement is stable against imperfections, to the ergodic regime, in which a pair of qubits becomes entangled with the rest of the lattice and the pairwise entanglement drops to zero. The transition is almost independent of the size of the quantum computer. We consider both the case of an initial maximally entangled and separable state. In this last case there is a broad crossover region in which the computer imperfections can be used to create a significant amount of pairwise entanglement.Comment: 4 pages, 4 figure

Flexual buckling of structural glass columns. Initial geometrical imperfection as a base for Monte Carlo simulation

In this paper Monte Carlo simulations of structural glass columns are presented. The simulation was performed according to the analytical second order theory of compressed elastic rods. A previous research on shape and size of initial geometrical imperfections is briefly summarized. An experimental analysis of glass columns that were performed for evaluation of equivalent geometrical imperfections is mentioned too

Metallographic evaluation of the weldability of high strength aluminium alloys using friction spot welding

Friction spot welding is a recent solid-state welding technique well suited for spot-joining lightweight materials in overlap condition. Aerospace and transport industries show great interest in this technique to join high-strength aluminium alloys, but published research is still limited. In this project, the link between process parameters and weld quality is investigated for EN AW-7075-T6 material. Techniques used are metallographic qualification, measurement of hardness reduction and lap shear strength. This paper focusses on the metallographic investigation of the weld region and its imperfections. Increasing joining time and heat input creates an easier material flow resulting in fewer imperfections. Limited plunge depths lead to typical interface imperfections. Variation in the rotational speed shows distinctive stir zone shapes as a consequence of severe stirring and frictional heat

CREDIT MARKET IMPERFECTIONS AND THE DISTRIBUTION OF POLICY RENTS: THE COMMON AGRICULTURAL POLICY IN THE NEW EU MEMBER STATES

This article analyses how credit market imperfections affect the impacts of subsidies by analyzing the effects of agricultural subsidies in the new Eastern Member States of the European Union with a partial equilibrium model which integrates credit and land market imperfections. We show that credit constraints have important implications for the distribution of policy rents. Credit market imperfections may induce very different effects of direct payments and lump-sum transfers.agricultural policy, imperfect credit markets, land market, policy rents, Agricultural and Food Policy, Agricultural Finance, Land Economics/Use,

Statistical properties of eigenvalues for an operating quantum computer with static imperfections

We investigate the transition to quantum chaos, induced by static imperfections, for an operating quantum computer that simulates efficiently a dynamical quantum system, the sawtooth map. For the different dynamical regimes of the map, we discuss the quantum chaos border induced by static imperfections by analyzing the statistical properties of the quantum computer eigenvalues. For small imperfection strengths the level spacing statistics is close to the case of quasi-integrable systems while above the border it is described by the random matrix theory. We have found that the border drops exponentially with the number of qubits, both in the ergodic and quasi-integrable dynamical regimes of the map characterized by a complex phase space structure. On the contrary, the regime with integrable map dynamics remains more stable against static imperfections since in this case the border drops only algebraically with the number of qubits.Comment: 9 pages, 10 figure

Deconvolving the information from an imperfect spherical gravitational wave antenna

We have studied the effects of imperfections in spherical gravitational wave antenna on our ability to properly interpret the data it will produce. The results of a numerical simulation are reported that quantitatively describe the systematic errors resulting from imperfections in various components of the antenna. In addition, the results of measurements on a room-temperature prototype are presented that verify it is possible to accurately deconvolve the data in practice.Comment: 5 pages, 2 figures, to be published in Europhysics Letter

Polarization Imperfections of Light in Interferometry

Disertační práce pojednává o polarizačních nedokonalostech optických komponentů, které jsou využívány ke kontrole a k transformaci polarizačního stavu světla. Získané teoretické výsledky jsou pak využity ve vybraných aplikacích, jež ke své činnosti využívají právě polarizace světla. Konkrétně se jedná o zařízení měřící vibrace oscilujících objektů, dále o interferenční měření dvojlomu v transparentních materiálech a konečně, o vybraná témata z optické kvantové komunikace.The emphasis of the dissertation is put on the investigating of polarization imperfections of optical components which are used to control and transform polarization of light. The theoretical results of this investigation are then applied to different applications which exploit light polarization, namely to the arrangements for high-resolution measurement of vibrating targets, to interferometric measurements for the determination of stress-induced birefringence in transparent materials and to the selected topics in quantum optical communication.