Search

Since the advent of bipolar transistor at Bell AT&T laboratories, the constant development of electronics industry over the past six decades have pushed the size of active semiconductor devices to its boundaries. The Moore's law which dictated doubling speed and halving physical dimensions every 18 months is now facing its end pretty soon. Current commercial technology is now being limited to the atomic spacing on one hand, and power density on the other hand. Solar power as well as quantum computing are also another relevant areas which would need certain physical implementations and materials. In short, the moving force and economic power behind this industry is enormous, however, technological bottlenecks are real and showing themselves very clearly now. Directions which may ultimately alleviate these restrictions are not too many, including two-dimensional nano-electronics, memristive networks, spintronics, compound semiconductor devices, optoelectronics interconnects, just to mention a few. This talk will address two important paradigms in this area 1) What are the real challenges in this technology? 2) What are the roots of retardation in our country and what can be done to merge into the international efforts? I will try to plant seeds to resolve some of the most basic misunderstandings in our academia and redirect the technology investments into a much more fruitful direction, with hopes that the next generation of our experts will have a much wider and relaxed atmosphere to excel and prosper.

Quantum Technology: Graphene Capacitor Enhances Nonlinear Circuitry at Low Temperatures Graphene capacitors, known to be strongly nonlinear at very low temperatures, now find novel applications in superconducting quantum circuits. A research carried out at Sharif University of Technology, Iran, and École Polytechnique Fédéral de Lausanne, Switzerland, reveals a whole new range of applications for quantum graphene capacitors. This is a three-layer device, made of two graphene layers separated by a two-dimensional dielectric. At reasonably small area, the capacitor exhibits strong nonlinearity leading to unprecedented applications in quantum technology. It could serve as the missing element in the toolbox of low temperature circuits, where nonlinear inductors and Josephson junctions mostly dominate. It also would enable a new and diverse range of quantum circuits, while easily providing access to ultrastrong coupling.

In this letter, it is proposed that cryogenic quantum bits can operate based on the nonlinearity due to the quantum capacitance of two-dimensional Dirac materials, and in particular graphene. The anharmonicity of a typical superconducting quantum bit is calculated, and the sensitivity of quantum bit frequency and anharmonicity with respect to temperature are found. Reasonable estimates reveal that a careful fabrication process can reveal expected properties, putting the context of quantum computing hardware into new perspectives.

We report a new analytical method for finding the exact solution of homogeneous linear ordinary differential equations with arbitrary order and variable coefficients. The method is based on the definition of jump transfer matrices and their extension into limiting differential form. The approach reduces the $n$th-order differential equation to a system of $n$ linear differential equations with unity order. The full analytical solution is then found by the perturbation technique. The important feature of the presented method is that it deals with the evolution of independent solutions, rather than its derivatives. We prove the validity of method by direct substitution of the solution in the original differential equation. We discuss the general properties of differential transfer matrices and present several analytical examples, showing the applicability of the method.

A method is described to solve the nonlinear Langevin equations arising from quadratic interactions in quantum mechanics. While the zeroth order linearization approximation to the operators is normally used, here, first and second order truncation perturbation schemes are proposed. These schemes employ higher-order system operators, and then approximate number operators with their corresponding mean boson numbers only where needed. Spectral densities of higher-order operators are derived, and an expression for the second-order correlation function at zero time-delay has been found, which reveals that the cavity photon occupation of an ideal laser at threshold reaches 6 − 2 , in good agreement with extensive numerical calculations. As further applications, analysis of the quantum anharmonic oscillator, calculation of Q-functions, analysis of quantum limited amplifiers, and nondemoliton measurements are provided.

In this paper, we present a detailed analysis of a two-dimensional lossless and non-dispersive structured conducting interface, which is approximated by a two-dimensional ideal one-component plasma-like conducting sheet enclosed by two isotropic dielectrics. We present a Green's function formalism to analyze the propagation of surface plasmons and find new expressions. We also present analytical extensions of the approach to include loss, and discuss the results and applications of the theory. We study the symmetry properties of eigenmodes and show that the symmetries of the eigenmodes at high-symmetry points of the Brillouin zone are similar to those of the E-polarization eigenmodes of a two-dimensional square-lattice photonic crystal. [ABSTRACT FROM AUTHOR]