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The advent of novel nonlinear materials has stirred unprecedented interest in exploring the use of temporal inhomogeneities to achieve novel forms of wave control, amidst the greater vision of engineering metamaterials across both space and time. When the properties of an unbounded medium are abruptly switched in time, propagating waves are efficiently converted to different frequencies, and partially coupled to their back-propagating phase-conjugate partners, through a process called time-reversal. However, in realistic materials the switching time is necessarily finite, playing a central role in the resulting temporal scattering features. By identifying and leveraging the crucial role of electromagnetic momentum conservation in time-reversal processes, here we develop a general analytical formalism to quantify time-reversal due to temporal inhomogeneities of arbitrary profile. We deploy our theory to develop a formalism, dual to spatial tapering, that enables the tailoring of a desired time-reversal spectral response, demonstrating its use for the realization of broadband frequency converters and filters.

In quasiclassical trajectory simulations of bimolecular reactions of polyatomic molecules, the sets of initial coordinates and momenta of the colliding molecules generated by the widely used normal mode sampling (NMS) are generally nonstationary and evolve during the initial free flight of the reactants. For several isotopologues of the CH4 + H abstraction reaction, the calculated cross sections were found to oscillate as a function of the initial reactant separation. The arising ambiguity can be removed by averaging over an entire period of such oscillations (1PA). Adiabatic switching (AS) produces stationary ensembles of initial states, allowing one to generate unambiguous reaction probabilities and cross sections regardless of the choice of coordinate system used in the zeroth-order harmonic Hamiltonian. In this work the accuracy of the 1PA method was tested against AS-based reactivity parameters. Overall, 1PA provides a reasonably good correction to the non-stationarity of the initial states generated by NMS, but in extreme cases the cross sections are overestimated by up to 70%, thus the accuracy of 1PA varies currently unpredictably and is often sensitive to the choice of coordinates used for NMS. Therefore, it seems advisable to use adiabatic switching to prepare initial states in quasiclassical trajectory simulations. [ABSTRACT FROM AUTHOR]

We establish adiabatic theorems with and without spectral gap conditions for general — typically dissipative — linear operators A (t) : D (A (t)) ⊂ X → X with time-independent domains D (A (t)) = D in some Banach space X. Compared to the previously known adiabatic theorems — especially those without a spectral gap condition — we do not require the considered spectral values λ (t) of A (t) to be (weakly) semisimple. We also impose only fairly weak regularity conditions. Applications are given to slowly time-varying open quantum systems and to adiabatic switching processes. [ABSTRACT FROM AUTHOR]

The paper compares three adiabatic logic designs like Efficient Charge Recovery Logic (ECRL), Modified Energy Recovery Logic (MERL) and Positive Feedback Adiabatic Logic (PFAL). A 2:1 multiplexer is implemented using these design techniques and the results are compared in terms of rise time, fall time, transistor count, delay, slew rate, etc. The designed circuits are simulated using mentor graphics VLSI design software Pyxis_v10.5_5_201606075. From the results, it is found that the delay of PFAL-based circuits is better compared to ECRL and MERL. [ABSTRACT FROM AUTHOR]

In this paper, an analytical model is proposed to estimate the energy consumption of n-input adiabatic logic gate. The model is based on RC linearization of the adiabatic circuit network. To validate the model expressions, simulations are carried out at 90 nm technology node using the Cadence Spectre simulator. Model validates with simulation results at a maximum error equals to 9.94%. Model expressions are also applied in comparison of energy performance of adiabatic logic and conventional CMOS logic. Proposed research work suggests the operating conditions which makes the adiabatic logic more energy efficient than conventional CMOS logic. [ABSTRACT FROM AUTHOR]

We present a time-dependent method for determining several approximate excited-state energies and wave functions using a vectorial approach to multidimensional supersymmetric quantum mechanics. First, a vectorial approach is used to generate the tensor sector two Hamiltonian, which is isospectral with the original scalar sector one Hamiltonian above the ground state of the sector one Hamiltonian. We construct a time-dependent Hamiltonian interpolating between the scalar sector one Hamiltonian and the tensor sector two Hamiltonian. Then, we can adiabatically switch from the ground state of the sector one Hamiltonian to the ground state of the sector two Hamiltonian by solving the time-dependent Schrödinger equation. In addition, by employing an initial wave packet orthogonal to that leading to the ground state of sector two, we also obtain the first-excited state of sector two. Construction of the orthogonal sector one states is trivial due to the tensor nature of sector two. The ground and first-excited states of the sector two Hamiltonian can be used with the charge operator to obtain the first two excited state wave functions of the sector one Hamiltonian. Excellent computational results are obtained for two-dimensional nonseparable degenerate and nondegenerate systems. [ABSTRACT FROM AUTHOR]

A simple modification of the definition of the S-matrix is proposed. It is expected that the divergences related to nonzero self-energies are considerably milder with the modified definition than with the usual one. This conjecture is verified in a few examples using perturbation theory. The proposed formula is written in terms of the total Hamiltonian operator and a free Hamiltonian operator and is therefore applicable in any case when these Hamiltonian operators are known. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a detailed design analysis of sequential circuits for quantum-dot cellular automata (QCA). This analysis encompasses flip-flop (FF) devices as well as circuits. Initially, a novel RS-type FF amenable to a QCA implementation is proposed. This FF extends a previous threshold-based configuration to QCA by taking into account the timing issues associated with the adiabatic switching of this technology. The characterization of a D-type FF as a device consisting of an embedded wire is also presented. Unique timing constraints in QCA sequential logic design are identified and investigated. An algorithm for assigning appropriate clocking zones to a QCA sequential circuit is proposed. A technique referred to as stretching is used in the algorithm to ensure timing and delay matching. This algorithm relies on a topological sorting and enumeration step to consistently traversing only once the edges of the graph representation of the QCA sequential circuit. Examples of QCA sequential circuits are provided. [Copyright &y& Elsevier]

We present a new simulation technique that allows accurate and very efficient determination of free energies as a function of temperature using a single constant temperature molecular dynamics or Monte Carlo simulation. The method is based on the dynamical reversible scaling of the potential energy function of the system of interest and is implemented using the adiabatic switching method. Application to the calculation of the free energy of crystalline silicon using a semi-empirical interatomic potential demonstrates that the reversible-scaling method provides an accurate and very efficient tool for the calculation of free energies over a wide temperature interval. [ABSTRACT FROM AUTHOR]

The presence of thermal noise dictates that an energy barrier is needed to preserve a binary state. Therefore, all electronic devices contain at least one energy barrier to control electron flow. The barrier properties determine the operating characteristics of electronic devices. Furthermore, changes in the barrier shape require changes in charge density. Operation of all charge transport devices includes charging/discharging capacitances to change barrier height. We analyze energy dissipation for several schemes of charging capacitors. A basic assumption of Reversible Computing is that the computing system is completely isolated from the thermal bath. An isolated system is a mathematical abstraction never perfectly realized in practice. Errors due to thermal excitations are equivalent to information erasure, and thus computation dissipates energy. Another source of energy dissipation is due to the need of measurement and control. To analyze this side of the problem, the Maxwell's Demon is a useful abstraction. We hold that apparent "energy savings" in models of adiabatic circuits result from neglecting the total energy needed by other parts of the system to implement the circuit. [ABSTRACT FROM AUTHOR]