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We consider a quantum bosonic channel that couples the input mode via a beam splitter or two-mode squeezer to an environmental mode that is prepared in an arbitrary state. We investigate the classical capacity of this channel, which we call a non-Gaussian attenuator or amplifier channel. If the environment state is thermal, we of course recover a Gaussian phase-covariant channel whose classical capacity is well known. Otherwise, we derive both a lower and an upper bound to the classical capacity of the channel, drawing inspiration from the classical treatment of the capacity of non-Gaussian additive-noise channels. We show that the lower bound to the capacity is always achievable and give examples where the non-Gaussianity of the channel can be exploited so that the communication rate beats the capacity of the Gaussian-equivalent channel (i.e. the channel where the environment state is replaced by a Gaussian state with the same covariance matrix). Finally, our upper bound leads us to formulate and investigate conjectures on the input state that minimizes the output entropy of non-Gaussian attenuator or amplifier channels. Solving these conjectures would be a main step toward accessing the capacity of a large class of non-Gaussian bosonic channels. [ABSTRACT FROM AUTHOR]

The paper is devoted to research the single-pass operating mode of active element on copper bromide vapors and time dependence of ratio «signal/ASE». The results show how the single-pass radiation power depends on the time delay between ASE pulse and the moment when the input signal enters to the active element. Light waveforms (ASE, input signal, output signal) are recorded at each time delay. The minimal time delay was 5.2 ns, the power radiation in this case was 3.47 W. The radiation power was reducing as the time delay was increased in increments of about 2 ns. The waveforms prove that the active element output signal contains two components: the first—ASE (amplified spontaneous emission), which is formed as result of the active substance atom excitation and their further spontaneous transitions; the second—single-pass radiation amplified by means of the inverse population of the active media. The waveforms allow to estimate the useful signal to noise ratio or other words «signal/ASE». The highest gain is provided with the lowest time delay due to the population inversion is maximum in this case. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Quantum physicists recognize that the very act of observing causes an inevitable "disturbance of the object observed. Topics include certiorari grant brewed much anticipation that the Court would, for the first time, shed light on § 230 of the Communications Decency Act of 19963 (CDA); and conspires with the person who committed such an act of international terrorism.

The effects on the electronic emission of the presence of nanoscale steps on a tungsten surface are investigated for the first time using three dimensional quantum mechanical models. The plane wave periodic version of the density functional theory is used to obtain the electronic wavefunctions and potentials for flat and corrugated structures. Local and averaged emitted current densities are obtained from them using time dependent perturbation theory. The orders of magnitude of the averaged current densities resulting from these calculations are similar for both flat and corrugated cases; however, strong enhancements are observed on the local current densities near the edges of the steps. These numerical results are compared with those of the analytical Fowler-Nordheim type models. The slopes of the Fowler-Nordheim plots are in good agreement for both numerical and analytical models, but the magnitudes of the emitted currents are significantly different. This is related to weaknesses in the description of the electronic structure of the metal in the analytical models. [ABSTRACT FROM AUTHOR]

The kinetic-energy dependences of the reactions M+ + CO where M+ = Re+, Os+, and Ir+ are studied using guided ion-beam tandem mass spectrometry. Formation of both MO+ and MC+ was observed in endothermic processes for all three metals. Modeling of the data provides thresholds that yield 0Kbond dissociation energies (BDEs, in eV) of 4.67 ± 0.09 (Re+-O), 4.82 ± 0.14 (Os+-O), 4.25 ± 0.11 (Ir+-O), 5.13 ± 0.12 (Re+-C), 6.14 ± 0.14 (Os+-C), and 6.58 ± 0.12 (Ir+-C). These BDEs agree well with literature values within experimental uncertainties demonstrating that ground state products are formed for all cases even though some of the reactions are formally spin forbidden. Quantum mechanical calculations at several levels of theory and using several basis sets were performed for MC+ and MO+ (with comparable results taken from the literature in some cases). B3LYP and CCSD(T) calculated ground state BDEs agree reasonably well with experimental values. The ground states in B3LYP and CCSD(T)/CBS calculations are 3Σ-(ReC+), 2▵ (OsC+), and 1Σ+ or 3▵ (IrC+) after including spin-orbit considerations. Relaxed potential energy surfaces (PESs) for the M+ + CO reactions show crossings between surfaces of different spin states such that products can be formed with no barriers in excess of the substantial endothermicities. Unlike results for these metal cations reacting with O2, the kinetic energy dependent cross sections for the formation of MO+ in the M+ + CO reactions exhibit only one feature. Reasons for this differential behavior are discussed in detail. [ABSTRACT FROM AUTHOR]

The effect of orientation of the NO(X) bond axis prior to rotationally inelastic collisions with Ar has been investigated experimentally and theoretically. A modification to conventional velocity-map imaging ion optics is described, which allows the orientation of hexapole state-selected NO(X) using a static electric field, followed by velocity map imaging of the resonantly ionized scattered products. Bond orientation resolved differential cross sections are measured experimentally for a series of spin-orbit conserving transitions and compared with quantum mechanical calculations. The agreement between experimental results and those from quantum mechanical calculations is generally good. Parity pairs, which have previously been observed in collisions of unpolarized NO with various rare gases, are not observed due to the coherent superposition of the two j = 1/2, Ω = 1/2 Λ-doublet levels in the orienting field. The normalized difference differential cross sections are found to depend predominantly on the final rotational state, and are not very sensitive to the final Λ-doublet level. The differential steric effect has also been investigated theoretically, by means of quantum mechanical and classical calculations. Classically, the differential steric effect can be understood by considering the steric requirement for different types of trajectories that contribute to different regions of the differential cross section. However, classical effects cannot account quantitatively for the differential steric asymmetry observed in NO(X) + Ar collisions, which reflects quantum interference from scattering at either end of the molecule. This quantum interference effect is dominated by the repulsive region of the potential. [ABSTRACT FROM AUTHOR]

Interference observed in a double-slit experiment most conclusively demonstrates the wave properties of particles. We construct a quantum mechanical double-slit interferometer by rovibrationally exciting molecular deuterium (D2) in a biaxial (v = 2, j = 2) state using Stark-induced adiabatic Raman passage, where v and j represent the vibrational and rotational quantum numbers, respectively. In D2 (v = 2, j = 2) → D2 (v = 2, j′ = 0) rotational relaxation via a cold collision with ground state helium, the two coherently coupled bond axis orientations in the biaxial state act as two slits that generate two indistinguishable quantum mechanical pathways connecting initial and final states of the colliding system. The interference disappears when we decouple the two orientations of the bond axis by separately constructing the uniaxial states of D2, unequivocally establishing the double-slit action of the biaxial state. This double slit opens new possibilities in the coherent control of molecular collisions. [ABSTRACT FROM AUTHOR]

We consider a linear quantum amplifier consisting of NA two-level atoms and study the problem of amplification of N-photon states. The N-photon states are associated with N-quantum states of the harmonic oscillator. We show that the process of interaction of the electromagnetic field with atoms can be associated with some transformation of the phase space and functions defined on this phase space. We consider the Husimi functions QN(q, p) of N-quantum states of the harmonic oscillator, which are defined on the phase space, investigate transformation of these functions, and find an explicit form of the density matrix of the amplified N-photon state. [ABSTRACT FROM AUTHOR]

Quantum information processing exploits all the features quantum mechanics offers. Among them there is the possibility to induce nonlinear maps on a quantum system by involving two or more identical copies of the given system in the same state. Such maps play a central role in distillation protocols used for quantum key distribution. We determine that such protocols may exhibit sensitive, quasi-chaotic evolution not only for pure initial states but also for mixed states, i.e., the complex dynamical behavior is not destroyed by small initial uncertainty. We show that the appearance of sensitive, complex dynamics associated with a fractal structure in the parameter space of the system has the character of a phase transition. The purity of the initial state plays the role of the control parameter, and the dimension of the fractal structure is independent of the purity value after passing the phase transition point. The critical purity coincides with the purity of a repelling fixed point of the dynamics, and we show that all the pre-images of states from the close neighborhood of pure chaotic initial states have purity larger than this. Initial states from this set can be considered as quasi-chaotic. [ABSTRACT FROM AUTHOR]

The integrated cascode DE power amplifier for RF calibration system toward measurement of bio‐sensor applications is presented in this paper. The proposed architecture includes cascode class‐D and class‐E amplifier stages that could provide better calibration accuracy in terms of wide bandwidth, power efficiency, high gain, minimum group delay, and lowest calibration system. The achieved high performance of proposed amplifier overcomes conventional measurement issues toward bio‐sensor application. The inductive π‐shape matching network drives RF input to class‐D stage and provides wide bandwidth of operation. While class‐E stage with T‐shape matching network maintains stable gain and high efficiency in desired band of operation. The performance of the CMOS proposed amplifier is executed in RF ADS simulator along with fabricated chip using commercial TSMC 65 nm manufacturing process. The simulated and measured data achieves Ku band (12 GHz to 18 GHz) with almost flat gain of 30 dB. The DE amplifier provides an output and saturated power of 17 dBm with highest power efficiency of 45%. The measured calibration factor at maximum resonant frequency of 13.5 GHz achieves best value of less than 2 dB within input power range of −50 dBm to 0 dBm. The lowest calibration factor provides best accuracy along with the other parameters and could be beneficial toward bio‐sensor measurement in the various applications. The calculated area of the fabricated chip is as 0.45*0.45mm2 where class‐E consuming area of 38% and class‐D of 44%. The fabricated chip consumes less power consumption of 3.2 mW under power supply of 1 V. [ABSTRACT FROM AUTHOR]

We study the impact of the imperfections and the finite-size effect on the continuous-variable quantum key distribution (CVQKD) protocol with the nondeterministic noiseless linear amplifier (NLA). The imperfections of the homodyne detector and the imperfect amplification process as well as the finite-size effect on parameter estimation procedure are considered. We can see that despite the imperfections of the homodyne detector, the maximum improved transmission distance can still reach the equivalence of 20log10g dB losses theoretically. Moreover, the analysis shows the imperfect amplification process of the NLA will slightly decrease the performance of the system. And we find the finite-size effect significantly influence the secret key rates of the NLA CVQKD protocol and the performance will approach the ideal asymptotic case with the increase of block size. [ABSTRACT FROM AUTHOR]

The dilemma of reconciling the contradictory evidence regarding the conformation of long solvated peptide chains is the so-called "reconciliation problem". Clues regarding the stability of certain conformations likely lie in the electronic structure at the peptide-solvent interface, but the peptide-solvent interaction is not fully understood. Here, we study the influence of aqueous solvent on peptide conformations by using classical molecular dynamics (MD) and quantum mechanical/molecular mechanical (QM/MM) energy calculations. The model systems include an 11-residue peptide, X2A7O2 (XAO), where X, A, and O denote diaminobutyric acid, alanine, and ornithine, respectively, and a 9-mer (Arg-Pro-Pro-Gly-Phe-Ser-Ala-Phe-Lys). Spectroscopic and MD data present conflicting evidence regarding the structure of XAO in water; some results indicate that XAO adopts a polyproline II (PII) conformation, whereas other findings suggest that XAO explores a range of conformations. To investigate this contradiction, we present here the results of MD simulations of XAO and the 9-mer in aqueous solution, combined with QM/MM energy calculations. [ABSTRACT FROM AUTHOR]

In this study, FT-IR and FT-Raman spectra of 3-methyl picolinic acid (MPA) are recorded in the ranges 4000-450 cm-1 and 4000-50 cm-1, respectively. The optimized geometry is obtained by scaled quantum mechanical calculations using density functional theory employing the B3LYP functional with the 6-311++G(d,p) basis set. Vibrational assignments are suggested for all the fundamental vibrations unambiguously, using the potential energy distribution obtained in the computations. The rms error between the observed and calculated frequencies is found to be 8.48 cm-1. The dipole moment, polarizability, and hyperpolarizability values are computed to study the NLO behavior of the molecule. The NBO analysis is made to study the stability of the molecule arising from hyperconjugative interactions and charge delocalization. [ABSTRACT FROM AUTHOR]

With the development of nuclear power, increasing attention is being paid to the treatment of nuclear waste gas, including 14 CH 4 . Therefore, it is desirable to develop high-capacity 14 CH 4 adsorption materials. Metal-organic frameworks (MOFs) are an appropriate choice due to their high capacity and tunable properties. MOF PCN-14 is among the best 14 CH 4 adsorption materials. Furthermore, uptake in PCN-14 can potentially be tuned by altering the 14 CH 4 -MOF interaction through metal substitution on open metal sites (OMS). Predicting the impact of metal substitution remains a challenge, however, because general interatomic potentials commonly used in calculating uptake do not properly describe interactions involving OMS. Here, a new interatomic potential that explicitly accounts for these interactions is derived from quantum-mechanical calculations. The potential reproduces both the measured 14 CH 4 isotherm for PCN-14 and the site preference for adsorption at OMS. Extension to 5 metal-substituted variants confirms that OMS composition can dramatically alter uptake, with Ni- and Ca-based compounds predicted to exceed the performance of Cu-PCN-14 largely. Trends in 14 CH 4 uptake correlate well with elementary MOF properties such as surface area, binding energy between metal site and 14 CH 4 molecule. [ABSTRACT FROM AUTHOR]

Quantum information-theoretic approach had been identified as a way to understand the foundations of quantum mechanics as early as 1950 due to Shannon. However, there hasn’t been enough advancement or rigorous development of the subject. In the following paper we try to find the relationship between a general quantum mechanical observable and von Neumann entropy. We find that the expectation values and the uncertainties of the observables have bounds which depend on the entropy. The results also show that von Neumann entropy is not just the uncertainty of the state but also encompasses the information about expectation values and uncertainties of any observable which depend on the observers choice for a particular measurement. Also a reverse uncertainty relation is derived for n quantum mechanical observables. [ABSTRACT FROM AUTHOR]

A series of structurally and electronically varied 2,6-di(1H-imidazol-2-yl)phenols that are ESIPT-capable (1–12) as well as the ESIPT-incapable 4,5-diphenyl-2-(3-(4,5-diphenyl-1H-imidazol-2-yl)phenyl)-1H-imidazole (13) were designed and comparatively studied for their molecular effects on their sensitivity and selectivity characteristics as fluorescent chemosensors of Cr3+, Zn2+, and Cd2+. Their single-crystal structures revealed a desired chain of intramolecular hydrogen bonding (ligand 12) as well as possible coordination modes. Probes 1–4 demonstrated very high turn-on sensitivity and selectivity as double fluorescent sensors for Cr3+ and Zn2+ at their different emission wavelengths (blue-shifted in the case of Zn2+). A remarkable 106-fold emission turn-on by Cr3+ was recorded for molecule 2, which, to the best of our knowledge, is an unheard of magnitude for Cr3+ sensitivity. The results suggested that a Cd2+ sensor could be developed by further derivatization of these probes. The possession of symmetrical substitution on both imidazole rings, multiple active protons involved in hydrogen intramolecular bonding relays, and the consequent ESIPT capability of the studied molecules were found to be very beneficial to their successful outcomes as high fluorescent turn-on chemosensors. Modification of the sensor properties, such as sensitivity and selectivity, was achieved through substituent manipulations at certain peripheral positions. Thus, deliberate molecular derivatization was found to be a tool for manipulating the interference and selectivity profiles. The Job plot, single-crystal results, and sustained large Stoke's shift in the presence of Cr3+ suggest a one-pocket N^O coordination in a 1 : 1 stoichiometry rather than a binuclear N^O^N two-pocket coordination. Quantum mechanical calculations on the model structures suggested that the successful turn-on results may be associated with the coplanarity settings of the imidazole and phenol rings. [ABSTRACT FROM AUTHOR]

In this paper, we explore THz range optical intersubband transition energies in a donor doped quantum well of a GaAs/AlGaAs system as a function of the insertion position of an AlAs monolayer in the GaAs quantum well. In simulated models, the optical transition energies between electron subband levels 1 and 2 were higher in the doped structure than in the undoped structure. This may be because the envelope wave function of the second electron subband strongly overlapped the envelope wave function of the first electron subband and influenced the optical intersubband transition between the two levels in the THz range. At different levels of bias voltage at the Schottky barrier on the donor doped structure, the electric field in the growth direction of the structure linearly increased the further away the AlAs monolayer was placed from the reference position. We also simulated the optical transition energies between acceptor energy levels of the acceptor doped structure as a function of the insertion position of the AlAs monolayer. The acceptor doped structure induced THz range emission whereas the undoped structure induced mid-IR emission. [ABSTRACT FROM AUTHOR]

Theoretical α-decay half-lives of some nuclei from ground state to ground state are calculated using different nuclear potential model including Coulomb proximity potential (CPPM), Royer proximity potential and Broglia and Winther 1991. The calculated values comparing with experimental data, it is observed that the CPPM model is in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

We show that the propositional system of a many-box model is always a set-representable effect algebra. In particular cases of 2-box and 1-box models, it is an orthomodular poset and an orthomodular lattice, respectively. We discuss the relation of the obtained results with the so-called Local Orthogonality principle. We argue that non-classical properties of box models are the result of a dual enrichment of the set of states caused by the impoverishment of the set of propositions. On the other hand, quantum mechanical models always have more propositions as well as more states than the classical ones. Consequently, we show that the box models cannot be considered as generalizations of quantum mechanical models and seeking additional principles that could allow us to “recover quantum correlations” in box models are, at least from the fundamental point of view, pointless. [ABSTRACT FROM AUTHOR]

Radiative lifetimes of the ro-vibrational bound states of HeLi + ( b 3 ∑ + ) are calculated quantum-mechanically when both bound-bound and bound-free processes are taken into account. The calculations are restricted to the initial states with low rotational quantum numbers. For the rotationless molecular ion, the shortest lifetime is 1.30 × 10 - 6 s of the ground vibrational state. With increasing vibration excitations the radiative lifetimes slightly increase, but keep below 10 - 5 s for the next 17 vibrational states, then they start to increase more rapidly up to 2.41 × 10 - 2 s for the highest vibrational state. The radiative lifetimes also tend to slightly prolong with increasing rotational excitations but stay on the same magnitude for the low rotational quantum numbers. [ABSTRACT FROM AUTHOR]

We present the elastic scattering analysis of the 12C+24Mg system by using the WKB approximation method within the framework of the barrier-internal wave decomposition over a wide range of energy from Elab = 16 MeV to 24.0 MeV. The results obtained are good agreement with the quantum mechanical (QM) calculation and experimental data. [ABSTRACT FROM AUTHOR]

Experimental studies have increasingly shown that metal–organic frameworks (MOFs) serve as excellent catalytic platforms for various organic reactions. Although the theoretical description of large MOF systems presents a major technical challenge, the hybrid QM/MM computational approach, which has proven highly useful in studying large systems such as enzymes, should have great potential for elucidating fundamental details of MOFs. It is also possible to combine two different levels of QM methods (QM/QM′). This digest paper reviews the applications of these hybrid approaches, which have been made to study catalysis and gas adsorption of MOF systems. [ABSTRACT FROM AUTHOR]

The widespread use of nanodiamond as a biomedical platform for drug-delivery, imaging, and subcellular tracking applications stems from its nontoxicity and unique quantum mechanical properties. Here, we extend this functionality to the domain of magnetic resonance, by demonstrating that the intrinsic electron spins on the nanodiamond surface can be used to hyperpolarize adsorbed liquid compounds at low fields and room temperature. By combining relaxation measurements with hyperpolarization, spins on the surface of the nanodiamond can be distinguished from those in the bulk liquid. These results are likely of use in signaling the controlled release of pharmaceutical payloads. [ABSTRACT FROM AUTHOR]

We report high photoresponse measured in a room temperature quantum cascade detector (QCD) based on a coupled quantum well design that operates with a peak response wavelength of 5.4 μm. The coupled quantum well design is expected to produce higher photocurrents when compared with device active regions that use a combination of simple quantum wells. The coupled quantum well QCD demonstrated high responsivity of 22mA/W at room temperature with a commonly used 45° wedge-based light coupling configuration. Application of a waveguide configuration to the proposed QCD yielded an elevated responsivity of ~130mA/W and a specific detectivity (D*) of 1.1×108 cm W-1 Hz1/2 at room temperature. [ABSTRACT FROM AUTHOR]

A Doherty power amplifier composed of GaAs IPDs (Lange coupler and Doherty combiner) and GaN MMICs (carrier amplifier and peaking amplifier) is presented for 5G massive multi‐input multi‐output (MIMO). No input phase compensation circuit and no output offset lines were used for a compact design and the assembled Doherty power amplifier is as small as 6.6 mm × 3.6 mm with a saturation output power of 46 dBm. The asymmetric Doherty power amplifier exhibits a gain greater than 27.8 dB, PAE greater than 39.8% at average output power of 38 dBm, and ACLR less than −27.7 dBc using a 20 MHz LTE signal with 7.5 dB PAR across 3.6‐3.8 GHz. [ABSTRACT FROM AUTHOR]

Raman spectra of orthoenstatite have been computed from first principles, employing the hybrid Hamiltonian WC1LYP. The calculated data show excellent agreement with the experimental data from literature with an absolute average difference of ~5 cm−1. The quantum mechanical simulation allowed the assignment of Raman features to specific vibrational modes. This enabled to assess quantitatively the contributions of internal (tetrahedral stretching) and external (tetrahedral chains and M1 and M2 cations) vibrations. Moreover, the mass substitution of 56Fe for 24Mg in the M1 and M2 sites and of 30Si and 18O for the 28Si and 16O sites, pointed out the relative contributions of the cations to each mode within different sites. The description of the Raman modes enabled to relate the major experimental peaks to specific structural vibrations, and to link the changes in crystal structure to those modes with pressure, temperature and composition. The results provide new clues to identify most suitable peaks for the investigation of the intracrystalline ordering of Fe and Mg in the M1 and M2 sites, and of Al in the tetrahedral and octahedral sites. Moreover we have been able to identify those peaks which are related to structural features, like tetrahedral bond distances. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We develop a fully quantum mechanical formalism to calculate ionic transition states in solids and determine diffusion constants for H in Si and Li and Fe in LiFePO 4 . The formalism is quantitative and does not involve empirical parameters. From the quantum mechanical treatment we recover some quantities known from classical theory, e.g. the temperature dependent diffusion constant reflects the activation energy at high T . At low temperature however we discover a constant diffusion rate linked to the ionic tunneling. Tunneling and hopping rates are considered on an equal footing and result from the same formalism. We apply the quantum mechanical formalism to the diffusion of H in Si and discover the influence of the zero point energy of the diffusive species in the potential well. For LiFePO 4 we shed some light on the importance of the cross channel diffusion probably intermediated by Fe anti-site vacancies in the understanding of the experimentally observed diffusion constant. This work opens up the possibility to study quantitatively diffusion e.g. in potential electrode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]

To elucidate the reaction mechanism of the ring cleavage of homogentisate by homogentisate dioxygenase, quantum mechanical/molecular mechanical (QM/MM) calculations were carried out by using two systems in different protonation states of the substrate C2 hydroxyl group. When the substrate C2 hydroxyl group is ionized (the ionized pathway), the superoxo attack on the substrate is the rate-limiting step in the catalytic cycle, with a barrier of 15.9 kcal/mol. Glu396 was found to play an important role in stabilizing the bridge species and its O-O cleavage product by donating a proton via a hydrogen-bonded water molecule. When the substrate C2 hydroxyl group is not ionized (the nonionized pathway), the O-O bond cleavage of the bridge species is the rate-limiting step, with a barrier of 15.3 kcal/mol. The QM/MM-optimized geometries for the dioxygen and alkylperoxo complexes using the nonionized model (for the C2 hydroxyl group) are in agreement with the experimental crystal structures, suggesting that the C2 hydroxyl group is more likely to be nonionized. [ABSTRACT FROM AUTHOR]

Theoretical as well as experimental studies in the literature suggest that defect sites associated with the threading dislocation lines within -type gallium nitride (GaN) act to trap free electrons from the bulk of this semiconductor material. As a result, the core of the threading dislocation lines become negatively charged. The charge accumulated along the core of a threading dislocation line should be screened by a charge of opposite polarity and equal in absolute value per unit length along the dislocation line. In the present work, we model this screened charge buildup along the threading dislocation lines by two concentric space-charge cylinders. Quantum mechanical theory of scattering in cylindrical coordinates is then employed in order to numerically compute the electron mobility limited by scattering from the charged threading dislocation lines. The dependence of the computed electron mobility on the dislocation line density and on the amount of charge accumulated per unit length along the core of the dislocation lines is also investigated in this work. Our computed electron mobility results are compared with results from existing calculations of the GaN dislocation scattering limited electron mobility in the literature. [ABSTRACT FROM AUTHOR]

This manuscript presents an exercise that utilizes mathematical software to explore Fourier transforms in the context of model quantum mechanical systems, thus providing a deeper mathematical understanding of relevant information often introduced and treated as a "black-box" in analytical chemistry courses. The exercise is given to undergraduate students in their third year during physical chemistry, thus providing a theoretical foundation for the subsequent introduction of such material in analytical instrumentation courses. With the reinforcement of familiar concepts such as the Heisenberg Uncertainty Principle, classical correspondence, and linear combinations in the context of both position and momentum space for a particle in a box, a better understanding of the mathematical implications of the Fourier transform is fostered. Subsequent analysis of a time-dependent function constructed via a linear combination and its transformation to the frequency domain provides a practical example relating to the Fourier processes applied in analytical spectroscopy. The final portion of the exercise returns to the position/momentum conjugate pair and explores how the construction of a narrow wavepacket via a sum of cosines illustrates the Uncertainty Principle once the probability density functions of each coordinate are analyzed. This exercise has been shown to not only reinforce fundamental concepts necessary for a true appreciation of quantum mechanics, but also help demystify the Fourier transform process for students taking analytical chemistry. [ABSTRACT FROM AUTHOR]

Double-barrier heterostructures are model systems for the study of electron tunneling and discrete energy levels in a quantum well (QW). Until now resonant tunneling phenomena in metallic QWs have been observed for limited thicknesses (1-2 nm) under which electron phase coherence is conserved. In the present study we show evidence of QW resonance states in Fe QWs up to 12 nm thick and at room temperature in fully epitaxial double MgA10c barrier magnetic tunnel junctions. The electron phase coherence displayed in this QW is of unprecedented quality because of a homogenous interface phase shift due to the small lattice mismatch at the Fe-MgA10v interface. The physical understanding of the critical role of interface strain on QW phase coherence will greatly promote the development of spin-dependent quantum resonant tunneling applications. [ABSTRACT FROM AUTHOR]

In this paper I give a new information-theoretic analysis of the formalisms and interpretations of quantum mechanics (QM) in general, and of two mainstream interpretations of quantum mechanics in particular: The Copenhagen interpretation and David Bohm's interpretation of quantum mechanics. Adopting Juan G. Roederer's reading of the notion of pragmatic information, I argue that pragmatic information is not applicable to the Copenhagen interpretation since the interpretation is primarily concerned with epistemology rather than ontology. However it perfectly fits Bohm's ontological interpretation of quantum mechanics in the realms of biotic and artificial systems. Viewing Bohm's interpretation of QM in the context of pragmatic information imposes serious limitations to the qualitative aspect of such an interpretation, making his extension of the notion active information to every level of reality illegitimate. Such limitations lead to the idea that, contrary to Bohm's claim, mind is not a more subtle aspect of reality via the quantum potential as active information, but the quantum potential as it affects particles in the double-slit experiment represents the non-algorithmic aspect of the mind as a genuine information processing system. This will provide an information-based ground, firstly, for refreshing our views on quantum interpretations and secondly, for a novel qualitative theory of the relationship of mind and matter in which mind-like properties are exclusive attributes of living systems. To this end, I will also take an information-theoretic approach to the notion of intentionality as interpreted by John Searle. [ABSTRACT FROM AUTHOR]

An improved continuous-variable quantum key distribution (CVQKD) protocol is proposed to improve the performance of CVQKD system under the local oscillator intensity attack by using a suitable noiseless linear amplifier (NLA) at the destination. This method can enhance the efficiency of the CVQKD scheme in terms of the maximum transmission distance, no matter whether the direct or reverse reconciliation is used. Simulation results show that there is a considerable increase in the transmission distance for the NLA-based CVQKD by adjusting the values of the parameters. [ABSTRACT FROM AUTHOR]

A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppress lasing action, creating a THz QC amplifier. The addition of reflection from an external target to the amplifier creates enough optical feedback to initiate lasing action and the resulting emission enhances photon-assisted transport, which in turn reduces the voltage across the device. At the peak gain point, the maximum photon density coupled back leads to a prominent self-mixing effect in the QC amplifier, leading to a high sensitivity, with a signal to noise ratio up to 55 dB, along with a fast data acquisition speed of 20 000 points per second. [ABSTRACT FROM AUTHOR]

The ultimate scaling limit and device physics of aggressively scaled phosphorene MOSFETs are examined by self-consistent multiscale quantum transport simulations. The MOSFET structure can effectively suppress the ambipolar conduction and decrease the leakage current, and thereby, is more scalable than the Schottky barrier FET structure. The interplay of quantum mechanical effects and highly anisotropic band structure plays a critical role for phosphorene transistors with a sub 10-nm channel length, in which the optimum choice of the transport crystalline direction is completely different from phosphorene FETs with a longer channel length. Even at a sub-10-nm channel length with considerable quantum tunneling effects, the anisotropic band structure still provides a better device performance in terms of ON-current over other 2-D semiconductors with nearly isotropic band structures, such as MoS2. With the optimum choice of the transport direction, both n- and p-type phosphorene FETs meet the International Technology Roadmap for Semiconductor (ITRS) target at the 5-nm technology node. [ABSTRACT FROM AUTHOR]

In this study, a combined quantum mechanical and experimental analyses were performed to investigate crystal structure of the immediate degradation product of TNT, 2-hydroxylamino-4,6-dinitrotoluene (2-HADNT) and to reveal its important chemical properties. Leakage of 2-HADNT has caused serious environmental pollution and therefore raises widespread concerns. In the quantum mechanical analysis, the B3LYP/6-311+G ** , B3LYP/aug-c-pVDZ, M06HF/aug-cc-pVDZ, and MP2/aug-cc-pVDZ methods were employed for geometrical optimization and single point calculations of chemical properties of the compound. Such properties include highest unoccupied molecular orbitals (HOMO) – lowest occupied molecular orbitals (LUMO) separation, dipole moment, atomization energy, and vibrational frequencies. Experimental analysis and validation showed that the energy minimized structures acquired from the quantum mechanical analysis were very similar to those obtained by X-ray crystallography. The 6-NO 2 groups twist out of plane with respect to the benzene ring in both the crystallographic and energy minimized structures. The 4-NO 2 group exhibits co-planarity with the phenyl ring in both the crystallographic and energy minimized structures as well. Unlike TNT, however, the energy barrier to orthogonal conformation is only 3.8 kcal/mol. In addition, considerable discrepancies between results obtained from the MP2 and B3LYP methods were observed, which suggest that it has to be very careful when applying B3LYP method to study such class of compounds. Through this study, a more accurate description of the chemical properties of dispersion-dominated aromatic systems was acquired. The chemical properties found from this study can help researchers to better understand the compound of 2-HADNT and to develop effective management plans for such compound so as to minimize its impact on the environment. [ABSTRACT FROM AUTHOR]

Two quantum modes interacting via local couplings to a dissipative bosonic field are investigated theoretically. The model considers two mechanical modes with distinct frequencies coupled optomechanically to the same cavity mode. The dissipative cavity field mediates the interaction between the mechanical modes but also leads to decoherence of the mechanical oscillators. Depending on the ratio between effective interaction strength and dissipation rate, which can be chosen via the pump detuning, the interaction assumes a quantum mechanical or classical character. The distinction between the two regimes is made by the ability of the mediated interaction to correlate the two mechanical modes non-classically. For any cavity decay, there is a regime where the two mechanical modes interact in a non-classical way, which leads us to conclude that optomechanical systems can serve as a model to experimentally study the transition of effective interactions mediated by classical or quantum-mechanical fields. [ABSTRACT FROM AUTHOR]

The characteristics of intramolecular hydrogen bonds (IHBs) of some substituted derivatives of hydroxyl Schiff bases of fulvene have been investigated. For this purpose, the quantum mechanical calculations using density functional theory at the B3LYP/6-311++G(d,p) level of theory, and also natural bond orbitals and atoms in molecules analyses have been employed. Investigations into some aromaticity indicators (HOMA and pEDA) confirm that aromaticity and electron delocalization in the IHB quasi-ring of 3-hydroxy-2-((methylimino)methyl)fulvene derivatives increase by increasing the electron-donating character of substituents. Unexpectedly, the IHB strength decreases with an increase in the π-electron delocalization in the quasi-ring of these fulvene derivatives. According to this study, at least for this series of compounds, the resonance-assisted hydrogen bond (RAHB) concept could not explain the trend of the IHB strength. Alternatively, we present a good correlation between the IHB strength and the σ-skeleton of the studied molecules, which keeps the HB donor and the HB acceptor coplanar and closer to each other to form stronger IHBs. [ABSTRACT FROM AUTHOR]

It is well known that exact quantum searches can be performed by the quantum amplitude amplification algorithm with some phase matching condition. However, recently it was shown that for some preparation states in a three-dimensional subspace, an exact search is impossible to accomplish. We show this impossibility derives from two sources: a problem of state restriction to a cyclic subspace and the solution of a linear system of equations with a $$k$$ -potent coefficient matrix. Furthermore, using said system of equations, we introduce a class of preparation states in a three-dimensional space that, even though the quantum amplitude amplification algorithm is unable to find the target state exactly, the same system of equations implies modifications to the quantum amplitude amplification algorithm under which exact solutions in three-dimensional subspaces can be found. We also prove that an inexact quantum search in the 3-potent case can find the target state with high probability if the Grover operator is iterated a number of times inversely proportional to the uncertainty of said 3-potent coefficient matrix as an observable operator. [ABSTRACT FROM AUTHOR]

It is commonly anticipated that gravity is subjected to the standard principles of quantum mechanics. Yet some - including Einstein - have questioned that presumption, whose empirical basis is weak. Indeed, recently Dyson has emphasized that no conventional experiment is capable of detecting individual gravitons. However, as we describe, if inflation occurred, the universe, by acting as an ideal graviton amplifier, affords such access. It produces a classical signal, in the form of macroscopic gravitational waves, in response to spontaneous (not induced) emission of gravitons. Thus recent BICEP2 observations of polarization in the cosmic microwave background (CMB) will, if confirmed, provide firm empirical evidence for the quantization of gravity. Their details also support quantitative ideas concerning the unification of strong, electromagnetic and weak forces, and of all these with gravity. [ABSTRACT FROM AUTHOR]

Cavity optomechanical phenomena, such as cooling, amplification, or optomechanically induced transparency, emerge due to a strong imbalance in the dissipation rates of the parametrically coupled electromagnetic and mechanical resonators. Here we analyze the reversed dissipation regime where the mechanical energy relaxation rate exceeds the energy decay rate of the electromagnetic cavity. We demonstrate that this regime allows for mechanically induced amplification (or cooling) of the electromagnetic mode. Gain, bandwidth, and added noise of this electromagnetic amplifier are derived and compared to amplification in the normal dissipation regime. In addition, we analyze the parametric instability, i.e., optomechanical Brillouin lasing, and contrast it to conventional optomechanical phonon lasing. Finally, we propose an experimental scheme that realizes the reversed dissipation regime using parametric coupling and optomechanical cooling with a second electromagnetic mode enabling quantumlimited amplification. Recent advances in high-Q superconducting microwave resonators make the reversed dissipation regime experimentally realizable. [ABSTRACT FROM AUTHOR]

The article reports that transistor speed is limiting factor for chip performance and increasingly on-chip or Back End of Line (BEOL) interconnects for limiting factor. It mentions that electrical resistance in nanoribbons of epitaxial graphene changes in various steps with the quantum mechanical principles. It offers information on timedependent-dielectric-breakdown (TDDB) and electromigration focused on interconnects

We describe a new kind of phase-preserving quantum amplifier which utilizes dissipative interactions in a parametrically coupled three-mode bosonic system. The use of dissipative interactions provides a fundamental advantage over standard cavity-based parametric amplifiers: large photon number gains are possible with quantum-limited added noise, with no limitation on the gain-bandwidth product. We show that the scheme is simple enough to be implemented both in optomechanical systems and in superconducting microwave circuits. [ABSTRACT FROM AUTHOR]