86 research outputs found
Classical simulation of Quantum Entanglement using Optical Transverse Modes in Multimode Waveguides
We discuss mode-entangled states based on the optical transverse modes of the
optical field propagating in multi-mode waveguides, which are classical analogs
of the quantum entangled states. The analogs are discussed in detail, including
the violation of the Bell inequality and the correlation properties of optical
pulses' group delays. The research on these analogs may be important, for it
not only provides useful insights into fundamental features of quantum
entanglement, but also yields new insights into quantum computation and quantum
communication.Comment: RevTeX v4, 17 pages and 4 figure
Properties of finite Gaussians and the discrete-continuous transition
Weyl's formulation of quantum mechanics opened the possibility of studying
the dynamics of quantum systems both in infinite-dimensional and
finite-dimensional systems. Based on Weyl's approach, generalized by Schwinger,
a self-consistent theoretical framework describing physical systems
characterised by a finite-dimensional space of states has been created. The
used mathematical formalism is further developed by adding finite-dimensional
versions of some notions and results from the continuous case. Discrete
versions of the continuous Gaussian functions have been defined by using the
Jacobi theta functions. We continue the investigation of the properties of
these finite Gaussians by following the analogy with the continuous case. We
study the uncertainty relation of finite Gaussian states, the form of the
associated Wigner quasi-distribution and the evolution under free-particle and
quantum harmonic oscillator Hamiltonians. In all cases, a particular emphasis
is put on the recovery of the known continuous-limit results when the dimension
of the system increases.Comment: 21 pages, 4 figure
Wigner phase space distribution as a wave function
We demonstrate that the Wigner function of a pure quantum state is a wave
function in a specially tuned Dirac bra-ket formalism and argue that the Wigner
function is in fact a probability amplitude for the quantum particle to be at a
certain point of the classical phase space. Additionally, we establish that in
the classical limit, the Wigner function transforms into a classical
Koopman-von Neumann wave function rather than into a classical probability
distribution. Since probability amplitude need not be positive, our findings
provide an alternative outlook on the Wigner function's negativity.Comment: 6 pages and 2 figure
Chiral tunneling and the Klein paradox in graphene
The so-called Klein paradox - unimpeded penetration of relativistic particles
through high and wide potential barriers - is one of the most exotic and
counterintuitive consequences of quantum electrodynamics (QED). The phenomenon
is discussed in many contexts in particle, nuclear and astro- physics but
direct tests of the Klein paradox using elementary particles have so far proved
impossible. Here we show that the effect can be tested in a conceptually simple
condensed-matter experiment by using electrostatic barriers in single- and
bi-layer graphene. Due to the chiral nature of their quasiparticles, quantum
tunneling in these materials becomes highly anisotropic, qualitatively
different from the case of normal, nonrelativistic electrons. Massless Dirac
fermions in graphene allow a close realization of Klein's gedanken experiment
whereas massive chiral fermions in bilayer graphene offer an interesting
complementary system that elucidates the basic physics involved.Comment: 15 pages, 4 figure
Phosphorene: Fabrication, Properties and Applications
Phosphorene, the single- or few-layer form of black phosphorus, was recently
rediscovered as a twodimensional layered material holding great promise for
applications in electronics and optoelectronics. Research into its fundamental
properties and device applications has since seen exponential growth. In this
Perspective, we review recent progress in phosphorene research, touching upon
topics on fabrication, properties, and applications; we also discuss challenges
and future research directions. We highlight the intrinsically anisotropic
electronic, transport, optoelectronic, thermoelectric, and mechanical
properties of phosphorene resulting from its puckered structure in contrast to
those of graphene and transition-metal dichalcogenides. The facile fabrication
and novel properties of phosphorene have inspired design and demonstration of
new nanodevices; however, further progress hinges on resolutions to technical
obstructions like surface degradation effects and non-scalable fabrication
techniques. We also briefly describe the latest developments of more
sophisticated design concepts and implementation schemes that address some of
the challenges in phosphorene research. It is expected that this fascinating
material will continue to offer tremendous opportunities for research and
development for the foreseeable future.Comment: invited perspective for JPC
Classical Simulation of Relativistic Quantum Mechanics in Periodic Optical Structures
Spatial and/or temporal propagation of light waves in periodic optical
structures offers a rather unique possibility to realize in a purely classical
setting the optical analogues of a wide variety of quantum phenomena rooted in
relativistic wave equations. In this work a brief overview of a few optical
analogues of relativistic quantum phenomena, based on either spatial light
transport in engineered photonic lattices or on temporal pulse propagation in
Bragg grating structures, is presented. Examples include spatial and temporal
photonic analogues of the Zitterbewegung of a relativistic electron, Klein
tunneling, vacuum decay and pair-production, the Dirac oscillator, the
relativistic Kronig-Penney model, and optical realizations of non-Hermitian
extensions of relativistic wave equations.Comment: review article (invited), 14 pages, 7 figures, 105 reference
Put It in Your Shoe It Will Make You Limp: British Menâs Online Responses to a Male Pill
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.This article analyzes online interactions between British men and other online readersâ comments in response to two news articles focused on a male contraceptive pill. The aim of the study was to explore how British menâs online accounts construct a male pill as a potential contraceptive option for family planning. The two online articles reported the scientific innovations, as well as the production and marketing, of a nonhormonal, plant-based pill for men. Discourse analysis was used to analyze the online comments, from which two discourses emerged: (a) âMen as responsible health consumersâ and (b) ââKilling spermâ and other side effects on semen.â When provided with the opportunity to take future responsibility for family planning, male readers were found to be unlikely to use a contraceptive pill. The men expressed the need for new options of contraception but, overall, felt a male pill was not the solution
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