We explore essential factors pertaining to the spatial directivity of quantum radiating source systems (QSSs), encompassing quantum antennas and quantum sensors. Our primary focus is on their capacity to control the emission of photons in specific spatial directions. We present a comprehensive definition of quantum directivity, drawing inspiration from Glauberâ\euro™s photon detection theory. This definition closely parallels the framework of analogous concepts in classical antenna theory. By conducting thorough conceptual and mathematical analysis, we address the challenge of characterizing the directive properties of a general QSS. Essentially, our approach presents a computational model that relies solely on the radiation field operatorâ\euro™s density as input.

Utilizing a crossdisciplinary approach, we explore Shannon information-theoretic characterizations of the information capacity limits of generic electromagnetic surfaces intended for possible use in wireless communication links. Our principal task is to first formulate at a general and rigorous level the electromagnetic theory of the information that can be extracted from the Maxwellian fields radiated by an arbitrarily-shaped continuous surface. This is then followed by a detailed derivation and illustration of practical physics-informed algorithms for computing approximations of the Shannon capacity of surfaces with any given geometry operating in Gaussian (AWGN) channels. Our formalism can address both near- and far-field information capacity scenarios, with a mathematical treatment that includes a complete characterization of the source-field polarization structure, mutual coupling, and interactions.

We describe a general framework for the modeling and analysis of Markovian quantum antenna systems viewed as a special problem in quantum stochastic dynamics. The quantum radiator, which can be used to spatially direct radiated quantum states in future quantum communication systems, is modeled as an open quantum system capable of controlling the composition of its radiation modes through external source manipulations while in continuous interaction with the surrounding thermal and random environment. Our analysis and computational method are based on deploying the Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) master equation to account for environment-induced jump processes such as quantum dissipation and decoherence. We construct a definition of the quantum antenna directivity inspired by the corresponding formulas in classical antenna theory and use the GKSL formalism to derive several versions of the quantum directivity formula. As a computational example, we study the flow of the density operator of a coupled two-level quantum dot (qubit) array, excited by classical external signals with variable amplitude and phase, which is evolved in time using the quantum Liouville-type equation (the master equation). It is shown that by manipulating the amplitude and phase excitations of individual quantum dots, one may significantly enhance the directive radiation properties of the Markovian quantum antenna system.

Achieving genuine (human-level) artificial general intelligence (AGI) is one of the major goals of computer science, engineering, psychology, and mathematics. In this article, we critically reexamine the relation between natural intelligence and artificial intelligence at a fairly general theoretical level. After identifying four major structural themes in natural intelligence, we move to the issue of AGI implementation through physical computing machines. Motivated by Penrose’s G¨ddelian argument refuting the thesis of AGI realizability via Turing machines, we formulate several theses on the noncomputable essence of AGI systems and suggest that infinitary noncomputability might constitute a viable path toward future AGI implementations, especially if coupled with nonlocality and a non-classical probabilistic structure such as the quantum case. A theoretical mathematical framework for non-Markovian stochastic dynamic systems is then presented and illustrated by describing multiagent AGI assemblages comprised of interconnected dynamic agents. We envision that such networked dynamical assemblages might be powered by noncomputable physics or arranged in an infinitary structure.

This study proposes a new approach to periodic multilayer mirrors (PMMs) characterizations based on measured X-ray reflectivity (XRR) data. Here, XRR data are used to reconstruct the internal structure of PMMs using grazing incidence X-ray reflectivity (GIXR). A mathematical model of electromagnetic wave reflection by PMMs is employed to implement forward prediction, which will then be used iteratively in a global optimization framework in order to reconstruct the PMM unknown structure parameters. A typical simulation of PMM often includes tens to thousands of unknown structure parameters, rendering standard curve fitting methods cumbersome and impractical. To make the PMM characterization method computationally feasible, this study combines implementation of the Levy flight particle swarm optimization (LFPSO) algorithm with a parallelized version of the electromagnetic solver X-Ray Calc in order to simplify the model parameter reconstruction process. Levy flight, a random walk wherein the Levy distribution is used to determine step size, is a more efficient search strategy for global optimization because of the long jumps made by the particles.  It is demonstrated that a PMM model with up to thousands of structure parameters can be reconstructed within several seconds on a regular workstation. The algorithm is tested with both measured and theoretical XRR data using in-house fabricated PMMs with known structures. Excellent agreement with the actual structures is observed, which is attained in short computation time. The new approach avoids manual curve fitting and simplified GIXR analysis and is observed to scale linearly with the size of the PMM structure, making it attractive for X-ray optics systems involving large-and-complex reflecting mirrors.

We investigate the problem of electromagnetic radiation in massive electromagnetism with focus on the directive radiation characteristics of Proca antennas (sources embedded into Proca metamaterial domains.) It is theoretically demonstrated that the recently proposed nonlocal Proca metamaterial implies the existence of point nonlocal sources possessing a perfectly isotropic radiation pattern. Based on this rigorous analysis, we derive exact expressions for the directive radiation patterns of arbitrary discrete distributions of Proca sources, i.e., radiating arrays emitting massive photons. Examples of linear discrete Proca arrays are given and comparison with massless photon radiation sources is provided.

The fusion of electromagnetic (EM) waves and information theory in wireless and waveguide communication technology has enjoyed a remarkable revival during the last few years. In particular, unlike traditional transceiver systems, the recently proposed information metasurface system directly links the controllable binary 2-D array sources with reradiated waves generated through electromagnetic scattering mechanisms, making the combination of electromagnetic and information theories highly desirable and natural. In this paper, EM in-formation characteristics of a direct digital modulation (DDM) system enabled by programmable information metasurface are analyzed. The information metasurface is used as a modulator of the illuminating field, while the scattered far-field complex amplitudes are measured, effectively treated as the received quantities. The posterior probability for a specific source coding pattern, conditioned over a given measured scattering fields, is obtained through Bayesian analysis technique, from which the average mutual information (AMI) is obtained in order to estimate the metasurface observation capability along any particular direction. The averaged receiver mutual information (ARMI) is then introduced to characterize generated field correlation structures along different observation directions. Based on ARMI, the joint observation capability is also analyzed. Furthermore, the channel capacity of such a system is derived, and the influencing factors are analyzed from four different perspectives, including the observation direction, the size of the information metasurface, potential joint observations in multiple directions, and the noise level. The proposed method, together with the various related performance measure metrics introduced therein, are expected to provide the research community with easy-to- implement quick tools for analyzing and designing current and future information metasurface-based communication systems, which can also be extended to other aspects in the now growing field of the electromagnetic theory of information.

We revisit the problem of realizing perfectly isotropic antennas based on recent developments in nonlocal antenna theory. The key obstacle against the existence of exactly isotropic antennas is traced back to the hairy ball theorem in algebraic and differential topology. A path blocking the applicability of this no-go theorem is to allow for complementary longitudinal modes to coexist with matching transverse modes in the antenna exterior region. Nonlocal antennas (radiators embedded into nonlocal metamaterial exterior domains) are possible future antenna technologies capable of dealing with both transverse and longitudinal modes. It is rigorously demonstrated that the recently proposed nonlocal Proca metamaterial (massive electromagnetism) leads to small nonlocal dipole antennas with perfectly isotropic radiation pattern. A tentative proposal for a possible experimental realization of perfectly isotropic radiators in the future is briefly outlined.

A new computational approach to quantum antennas based on first principle open stochastic quantum dynamics. We develop a general computational approach for the analysis and design of quantum antenna systems comprised of coupled quantum dot arrays interacting with external fields and producing quantum radiation. The method is based on using the GKSL master equation to model quantum dissipation and decoherence. The density operator of a coupled two-level quantum dot (qbit) array, excited by classical external signals with variable amplitude and phase, is evolved in time using a quantum Liouville-like equation (the master equation). We illustrate the method in a numerical example where it is shown that manipulating the phase excitations of individual quantum dots may significantly enhance the directive radiation properties of the quantum dot antenna system

We develop foundations for the emerging field of quantum antennas using relativistic quantum field theory. We show that the concept of “antenna” goes beyond electromagnetic waves. Any quantum radiation can be treated within quantum antenna theory, not only electromagnetic or acoustic radiation that dominated the field so far.

A fairly general and unified approach to nonlocality in material continua is introduced here. This work aims at proposing new mathematical and conceptual foundations for the emerging topic of nonlocal metamaterials suitable for physicists, engineers, mathematicians, and materials scientists. The text develops an original rigorous theory, a detailed example involving nonlocal semiconductor metamaterials, and extensive literature review and discussion of possible applications of nonlocal metamaterials.

An alternative to conventional spacetime is rigoursly formulated for nonlocal electromagnetism using the general concept of fiber bundle superspace.