Search results for "Quantum"

Code Interoperability and Standard Data Formats in Quantum Chemistry and Quantum Dynamics: The Q5/Q5cost Data Model

2014

Code interoperability and the search for domain-specific standard data formats represent critical issues in many areas of computational science. The advent of novel computing infrastructures such as computational grids and clouds make these issues even more urgent. The design and implementation of a common data format for quantum chemistry (QC) and quantum dynamics (QD) computer programs is discussed with reference to the research performed in the course of two Collaboration in Science and Technology Actions. The specific data models adopted, Q5Cost and D5Cost, are shown to work for a number of interoperating codes, regardless of the type and amount of information (small or large datasets) …

Approximate supervised learning of quantum gates via ancillary qubits

2018

We present strategies for the training of a qubit network aimed at the ancilla-assisted synthesis of multi-qubit gates based on a set of restricted resources. By assuming the availability of only time-independent single and two-qubit interactions, we introduce and describe a supervised learning strategy implemented through momentum-stochastic gradient descent with automatic differentiation methods. We demonstrate the effectiveness of the scheme by discussing the implementation of non-trivial three qubit operations, including a Quantum Fourier Transform (QFT) and a half-adder gate.

Electronic properties of graphene: A learning path for undergraduate students

2016

The purpose of this work is to present a learning path aimed at deepening student understanding of the fundamental concepts underlying the electronic properties of new materials, graphene in particular. To achieve this task, we propose a five-week long workshop where students may be introduced to fundamental concepts of advanced physics, rarely used in learning paths, such as the symmetry properties of the crystal lattice, the group theory , the features of the free electron wave functions and energy levels, the relativistic Dirac equation. Particular emphasis is given to the manner of introducing these concepts, since an essential knowledge of solid state physics, quantum physics and relat…

Surface plasmon interference fringes in back-reflection

2010

We report the experimental observation of surface plasmon polariton (SPP) interference fringes with near-unity visibility and half-wavelength periodicity obtained in back reflection on a Bragg mirror. The presented method based on leakage radiation microscopy (LRM) represents an alternative solution to optical near-field analysis and opens new ways for the quantitative analysis of SPP fringes. With LRM we investigate various SPP interference patterns and analyze the high reflectivity of Bragg mirror in comparison with theoretical models.

Quantum Field Theory

2018

Quantum field theory (QFT) shares many of its philosophical problems with quantum mechanics. This applies in particular to the quantum measurement process and the connected interpretive problems, to which QFT contributes hardly any new aspects, let alone solutions. The question as to how the objects described by the theory are spatially embedded was already also discussed for quantum mechanics. However, the new mathematical structure of QFT promises new answers, which renders the spatiotemporal interpretation of QFT the pivotal question. In this chapter, we sketch the mathematical characteristics of QFT and show that a particle as well as a field interpretation breaks down.

The su(2|1) Model of Electroweak Interactions and Its Connection to NC Geometry

2002

I review the su(2|1) model of electroweak interactions which is essentially based on the super Lie algebra su(2|1), thus incorporating both usual gauge fields and Higgs fields in one generalized Yang-Mills field. Special emphasis is put on the natural appearance of spontaneous symmetry breaking and other appealing features of the model like generation mixing. Also the connection of the model to noncommutative geometry is briefly discussed.

A Mechanistic Reading of Quantum Laser Theory

2015

Quantum laser theory proceeds in a way that seems at variance with the mechanistic model of explanation. First, as is typical for a complex systems theory, the detailed behavior of the component parts plays a surprisingly subordinate role. In particular, the so-called “enslaving principle” seems to defy a mechanistic reading. Moreover, being quantum objects, the “parts” of a laser are neither located in space nor describable as separate entities. I want to show that, despite these apparent obstacles, quantum laser theory constitutes a good example of a mechanistic explanation in a quantum physical setting, provided that one broadens the notion of mechanism. One may feel that such adjustment…

Parametrizations of density matrices

2011

This article gives a brief overview of some recent progress in the characterization and parametrization of density matrices of finite dimensional systems. We discuss in some detail the Bloch-vector and Jarlskog parametrizations and mention briefly the coset parametrization. As applications of the Bloch parametrization we discuss the trace invariants for the case of time dependent Hamiltonians and in some detail the dynamics of three-level systems. Furthermore, the Bloch vector of two-qubit systems as well as the use of the polarization operator basis is indicated. As the main application of the Jarlskog parametrization we construct density matrices for composite systems. In addition, some r…

Why a Quantum Tool in Classical Contexts?

2012

Reflections on the Nature of the Periodic Table of the Elements: Implications in Chemical Education

2014

The periodic table of the elements (PTE) results essential to understand our nature and place in the whole of beings. The same happens with our food, drugs, materials, etc. A series of questions were asked to introduce PTE and provide answers. The ideas in PTE should be valued by the number of questions that they generate. The PTE was related to electron configurations. The emergence of elements (nucleosynthesis) in physics was explained. The PTE results essential to understand our nature and place in the whole of beings. The same happens with our food, drugs, materials, etc. Schwarz and Rich asked a series of questions (Qs) to introduce PTE and provided answers. The ideas on PTE should be …