Correlation Functions and Spin

The k-electron correlation function of a free chaotic electron beam is derived with the spin degree of freedom taken into account. It is shown that it can be expressed with the help of correlation functions for a polarized electron beam of all orders up to k and the degree of spin polarization. The form of the correlation function suggests that if the electron beam is not highly polarized, observing multi-particle correlations should be difficult. The result can be applied also to chaotic photon beams, the degree of spin polarization being replaced by the degree of polarization.Comment: 6 pages, 1 eps figure, accepted to Phys. Rev.

Inequalities for electron-field correlation functions

I show that there exists a class of inequalities between correlation functions of different orders of a chaotic electron field. These inequalities lead to the antibunching effect and are a consequence of the fact that electrons are fermions -- indistinguishable particles with antisymmetric states. The derivation of the inequalities is based on the known form of the correlation functions for the chaotic state and on the properties of matrices and determinants.Comment: 8 pages Latex2e, 2 eps figure

Absolute instruments and perfect imaging in geometrical optics

We investigate imaging by spherically symmetric absolute instruments that provide perfect imaging in the sense of geometrical optics. We derive a number of properties of such devices, present a general method for designing them and use this method to propose several new absolute instruments, in particular a lens providing a stigmatic image of an optically homogeneous region and having a moderate refractive index range.Comment: 20 pages, 9 image

Partial Transmutation of Singularities in Optical Instruments

Some interesting optical instruments such as the Eaton lens and the Invisible Sphere require singularities of the refractive index for their implementation. We show how to transmute those singularities into harmless topological defects in anisotropic media without the need for anomalous material properties

Active absorption of electromagnetic pulses in a cavity

7 pages, 4 figuresAuthor version of the article. The version of record is available from the publisher via: http://dx.doi.org/10.1088/1367-2630/17/5/053050 and is an open access article.© 2015 IOP Publishing Ltd and Deutsche Physikalische GesellschaftWe show that a pulse of electromagnetic radiation launched into a cavity can be completely absorbed into an infinitesimal region of space, provided one has a high degree of control over the current flowing through this region. We work out explicit examples of this effect in a cubic cavity and a cylindrical one, and experimentally demonstrate the effect in the microwave regime.Engineering and Physical Sciences Research Council (EPSRC)Czech Science Foundatio

Combinations of generalized lenses that satisfy the edge-imaging condition of transformation optics.

We recently introduced the edge-imaging condition, a necessary condition for all generalized lenses (glenses) [J. Opt. Soc. Am. A33, 962 (2016)JOAOD60740-323210.1364/JOSAA.33.000962] in a ray-optical transformation-optics (RTO) device that share a common edge [Opt. Express26, 17872 (2018)OPEXFF1094-408710.1364/OE.26.017872]. The edge-imaging condition states that, in combination, such glenses must image every point to itself. Here we begin the process of building up a library of combinations of glenses that satisfy the edge-imaging condition, starting with all relevant combinations of up to three glenses. As it grows, this library should become increasingly useful when constructing lens-based RTO devices

Optical triangulations of curved spaces

Not only do curved spaces fascinate scientists and non-scientists, but they are also at the heart of general relativity and modern theories of quantum gravity. Optical systems can provide models for the wave and quantum behavior of curved spaces. Here we show how to construct optical systems that simulate triangulations of 3D curved spaces, for example, the curved 3D surface of a 4D hypersphere. Our work offers a new approach to the optical simulation of curved spaces, and has the potential to lead to new ways of thinking about physics in curved spaces and simulating otherwise inaccessible phenomena in non-Euclidean geometries

Superantenna made of transformation media

We show how transformation media can make a superantenna that is either completely invisible or focuses incoming light into a needle-sharp beam. Our idea is based on representating three-dimensional space as a foliage of sheets and performing two-dimensional conformal maps on each shee

Continuous Variable Quantum State Sharing via Quantum Disentanglement

Quantum state sharing is a protocol where perfect reconstruction of quantum states is achieved with incomplete or partial information in a multi-partite quantum networks. Quantum state sharing allows for secure communication in a quantum network where partial information is lost or acquired by malicious parties. This protocol utilizes entanglement for the secret state distribution, and a class of "quantum disentangling" protocols for the state reconstruction. We demonstrate a quantum state sharing protocol in which a tripartite entangled state is used to encode and distribute a secret state to three players. Any two of these players can collaborate to reconstruct the secret state, whilst individual players obtain no information. We investigate a number of quantum disentangling processes and experimentally demonstrate quantum state reconstruction using two of these protocols. We experimentally measure a fidelity, averaged over all reconstruction permutations, of F = 0.73. A result achievable only by using quantum resources.Comment: Published, Phys. Rev. A 71, 033814 (2005) (7 figures, 11 pages