Quantum Dipole Research Articles

New Molecularly Flexible Self-Assembling Benzothiadiazole Derivatives: Mesomorphism And DFT Investigations

In the present study, we have synthesized symmetric/unsymmetrical BTD embedded self-assembling molecules and investigated for their mesomorphic properties. Two symmetrical series (BTDK-(2-18) and BTDC-(4-18)) comprises benzothiadiazole moiety as a central core unit which is connected to two different systematically varied end-groups, alkoxy ester and alkoxy coumaryl unit connected through ether and imine linkages. On the other hand, the asymmetric molecules have an alkoxy chalconyl unit at one end and a formyl group at the other. It was observed that, the mesomorphism is completely depends on the molecular flexibility. New molecules revealed mesomorphic behaviour with N (nematic), SmA (smectic-A) and SmC (smectic-C) mesophase with high thermal stability and greater range. Changes in mesogenic units (alkoxy ester & alkoxy coumaryl unit) and the impact of altering the alkoxy chain at both ends have been investigated. Interesting evaluation has been carried out on the molecular flexibility which resulted in different mesomorphic behaviour of molecules under study. Furthermore, the experimentally established values of the mesophase thermal stability (Tc) and mesophase temperature ranges (ΔTSmA, ΔTSmC, and ΔTN), as well as the type of the mesophase, were related to the calculated quantum chemical parameters (Frontier molecular orbitals (FMOs), Aspect Ratio, Polarizability, dipole moment, molecular and electrostatic potential (MEP)) that were obtained by using the DFT method of the investigated compounds.

Consciousness: a quantum optical effect in fluorescent protein pathways

This paper presents a physical mechanism of embodied consciousness based on the dynamic organicity theory. We use the entropic pilot wave theory to describe the quantum dipole oscillations from dipole-bound delocalized (quasi-free) electrons in nonpolar nanocavities of aromatic amino acid residues (benzene moiety /cyclic hydrocarbons that contain resonance structures) and their fluorescent pathways. These pathways contain cavity quasipolariton condensates composed of quantized polarization waves of entangled photons. The behavior of oscillating molecular dipoles is influenced by the quantum nature of dynamic organicity, which causes energy fluctuations necessary to move delocalized electrons and create bare polaritons (quantized polarization waves). These waves correspond to photon quasiparticles interacting with water molecules to form quasipolaritons, softened by interacting with hydroxide ions (OH-) within crystal lattices of interfacial water H30. When [H3O+]=[OH−], the solution is neutral in hydrophobic nanocavities. In such nonpolar cavities, evanescent photons (non-radiative transitions in the absence of any source) are emitted while protons (H+) diffuse due to recombination with hydroxide (OH-) ions, acting as protonic analogs of ‘holes’ or excitons. In protein pores, proton motion strongly coupled with π-electron delocalization is a conduit for exciton-photon (polariton) and its polarization wave component. Internal energy fluctuations comprise both quantum potential energy and negative quantum kinetic energy. We explore how quantum potential energy influences the negentropic effect of a 'repulsive force' guided by entropic pilot waves through pilot wave force (negentropic force), functioning as an information-based action of the polarization wave as a conduit of the cavity quasipolariton. When the rate of change of quantum entropy is zero, and momentum of the polarization wave is zero the internal energy transduction between quantum potential energy to quantum kinetic energy manifests as the negentropic force and facilitates the movement of information-based action for information encoding when negative quantum kinetic energy happens at certain times. Experiments have shown that biphoton entanglement interferes with anaesthetics. We postulate that the disruption of cavity polaritonic condensate through its polarization wave component disrupts the decoding of information, suggesting consciousness is attributed to a quantum optical effect. Therefore, we further theorize that consciousness is attributed to the negative quantum kinetic energy of the polarization wave, which provides an informational structure of multiscale redundancy when negentropic action reduces information redundancy. This has profound implications for understanding consciousness as nonmechanical action channeled through negentropic force when the rate of change of quantum entropy is zero.

Quantum dipole interactions and transient hydrogen bond orientation order in cells, cellular membranes and myelin sheath: Implications for MRI signal relaxation, anisotropy, and T1 magnetic field dependence.

Despite significant impact on the study of human brain, MRI lacks a theory of signal formation that integrates quantum interactions involving proton dipoles (a primary MRI signal source) with brain intricate cellular environment. The purpose of the present study is developing such a theory. We introduce the Transient Hydrogen Bond (THB) model, where THB-mediated quantum dipole interactions between water and protons of hydrophilic heads of amphipathic biomolecules forming cells, cellular membranes and myelin sheath serve as a major source of MR signal relaxation. The THB theory predicts the existence of a hydrogen-bond-driven structural order of dipole-dipole connections within THBs as a primary factor for the anisotropy observed in MRI signal relaxation. We have also demonstrated that the conventional Lorentzian spectral density function decreases too fast at high frequencies to adequately capture the field dependence of brain MRI signal relaxation. To bridge this gap, we introduced a stretched spectral density function that surpasses the limitations of Lorentzian dispersion. In human brain, our findings reveal that at any time point only about 4% to 7% of water protons are engaged in quantum encounters within THBs. These ultra-short (2 to 3 ns), but frequent quantum spin exchanges lead to gradual recovery of magnetization toward thermodynamic equilibrium, that is, relaxation of MRI signal. By incorporating quantum proton interactions involved in brain imaging, the THB approach introduces new insights on the complex relationship between brain tissue cellular structure and MRI measurements, thus offering a promising new tool for better understanding of brain microstructure in health and disease.

Insight on the structural, electronic and optical properties of Zn, Ga-doped/dual-doped graphitic carbon nitride for visible-light applications

The density functional theory (DFT) was applied for the first time to study the doping and co-doping of Ga and Zn metals on graphitic carbon nitride (g-C3N4). The doping of these metal impurities into g-C3N4 leads to a significant decrease in the bandgap energy. Moreover, the co-doping leads to even lower bandgap energy than either individual Zn or Ga-doped g-C3N4. The theoretical electronic and optical properties including the density of state (DOS), energy levels of the frontier orbital, excited state lifetime, and molecular electrostatic potential of the doped and co-doped g-C3N4 support their application in UV–visible light-based technologies. The quantum mechanical parameters (energy band gap, binding energy, exciton energy, softness, hardness) and dipole moment exhibit higher values (ranging from 1.36 to 4.94 D) compared to the bare g-C3N4 (0.29 D), indicating better solubility in the water solvent. The time-dependent DFT (TD-DFT) calculations showed absorption maxima in between the UV–Vis region (309–878 nm). Additionally, charge transfer characteristics, transition density matrix (TDM), excited state lifetime and light harvesting efficiency (LHE) were investigated. Overall, these theoretical studies suggest that doped and co-doped g-C3N4 are excellent candidates for electronic semiconductor devices, light-emitting diodes (LEDs), solar cells, and photodetectors.

A tip-enhanced quantum emitter with integrated TiO2 slot waveguides in the optical regime

We study the coupling between a nanoscopic dielectric slot waveguide and a metallic-tip-enhanced dipole quantum emitter and search for optimal emission and guiding of photons along a titanium dioxide photonic waveguide. Finite element calculations are used to characterize the mode properties of the waveguide over a range of parameters and predict the efficiency of emission guidance along the waveguide. We show how the effective quantum yield is dependent on the waveguide parameters as well as the dipole position and orientation and show that the integrated system can reach a maximum quantum yield of more than 30% along each direction of the waveguide. By placing the dipole emitter near the apex of a silver nanotip situated above or inside the slot waveguide to increase the overall emission rate, we also enable the capability of controlling the emitter–waveguide​ coupling in situ. We numerically compute the excitation and radiation fields and find that despite a reduction in the quantum yield, a 35-fold increase in the overall emission rate can be obtained due to very large field enhancement factors of up to 4000 at the location of the dipole. By using alternative materials for the tip, this tip-enhanced-waveguide approach has the potential of further increasing the guided photon emission rate. With the possibility of controlling emitter–waveguide coupling in situ, this tip-enhanced emitter configuration provides an alternative approach for the realization of an efficient single-photon source.

Spectroscopic, structural, and intermolecular interactions of 4-(2-hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide enol-imine and keto-amine isomers

The spectroscopic (IR vibrational snd UV–vis analysis), structural, electronic properties, NBO, QTAIM studies of enol-imine (A) and keto-amine (B) isomers of 4-(2‑hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide was investigated using ωB97XD, PBE0, M06–2X, B3LYP-GD3(BJ), and TPSS functionals with the 6–311++G(d, p) basis set within the framework of density functional theory (DFT). The calculations were carried out in the gas phase and in solvents (benzene, chloroform, DMSO, and ethanol), and compared with experimental data. Global quantum descriptors, dipole moment, and thermodynamic properties were further calculated to predict the charge distribution, reactivity, and stability of the isomer forms of the titled compound. Results show that the PBE0 theoretical method gave a more reliable estimation of the experimental IR vibrational frequencies for isomers A and B, compared with other functionals. Structural analysis shows that geometrical parameters obtained for ωB97XD functional for both isomers A and B were consistent with the experimental results. For UV–vis analysis, the B3LYP-GD3(BJ) with the smallest MAPE for isomer A and ωB97XD method with the least MAPE for isomer B have the UV–vis values in close agreement with experimental data. Dipole moment calculations show that electron charge distribution is higher in isomer B, evident from the donor-acceptor interaction pattern observed from the NBO calculations. Energy, HOMO-LUMO energy gap, and thermodynamic calculations indicate that isomer A has higher stability while isomer B has higher reactivity.

Controlling Single‐Photon Emission with Ultrathin Transdimensional Plasmonic Films

AbstractThe properties of a two‐level quantum dipole emitter near an ultrathin transdimensional plasmonic film are studied theoretically. The model system studied mimics a solid‐state single‐photon source device. Using realistic experimental parameters, the spontaneous and stimulated emission intensity profiles are computed as functions of the excitation frequency and film thickness, followed by the analysis of the second‐order photon correlations to explore the photon antibunching effect. It is shown that ultrathin transdimensional plasmonic films can greatly improve photon antibunching with thickness reduction, which allows one to control the quantum properties of light and make them more pronounced. Knowledge of these features is advantageous for solid‐state single‐photon source device engineering and overall for the development of the new integrated quantum photonics material platform based on the transdimensional plasmonic films.

Adsorptive removal of toxic malachite green from its aqueous solution by Bambusa vulgaris leaves and its acid-treated form: DFT, MPR and GA modeling

In the current investigation, bamboo leaves (BL), H2SO4 treated bamboo leaves (SBL), and H3PO4 treated bamboo leaves (PBL) were utilized as biosorbents for the elimination of Malachite Green (MG) from the synthetic medium. The adsorption study was executed under the variation of different experimental conditions like pH, biosorbent dosage, contact time, and the temperature on the MG. Langmuir isotherm fit the adsorption data with maximum monolayer adsorption capacity, 151.735 mg/g at 298 K − 168.339 mg/g at 318 K for PBL. The data fitted the pseudo-2nd -order kinetic model for all three adsorbents with a correlation coefficient greater than 0.99, indicating that chemisorption controls adsorption. The Dubinin-Radushkevich isotherm indicated that the mean sorption energy (E) is a physisorption mechanism. So, the process involves physical sorption as well as chemical sorption processes with negligible sorption energy. The FTIR, Raman Spectra, and 13C NMR results show that different functional groups of cellulose, hemicellulose and lignin are involved in MG elimination. The theoretical studies were applied for a deeper understanding of the adsorption mechanism of MG using semi-empirical quantum chemical calculations. The DFT Calculations yielded valuable information about quantum chemical properties, like EHOMO, ELUMO, electrophilicity, chemical reactivity, dipole moment, and hardness for adsorbent/adsorbate components and the binding energy from adsorbent/adsorbate interactions. Multiple polynomial regression and genetic algorithm also have been successfully applied to predict the removal percentage of malachite green.

Consciousness, Cognition and the Neuronal Cytoskeleton - A New Paradigm Needed in Neuroscience.

Viewing the brain as a complex computer of simple neurons cannot account for consciousness nor essential features of cognition. Single cell organisms with no synapses perform purposeful intelligent functions using their cytoskeletal microtubules. A new paradigm is needed to view the brain as a scale-invariant hierarchy extending both upward from the level of neurons to larger and larger neuronal networks, but also downward, inward, to deeper, faster quantum and classical processes in cytoskeletal microtubules inside neurons. Evidence shows self-similar patterns of conductive resonances repeating in terahertz, gigahertz, megahertz, kilohertz and hertz frequency ranges in microtubules. These conductive resonances apparently originate in terahertz quantum dipole oscillations and optical interactions among pi electron resonance clouds of aromatic amino acid rings of tryptophan, phenylalanine and tyrosine within each tubulin, the component subunit of microtubules, and the brain’s most abundant protein. Evidence from cultured neuronal networks also now shows that gigahertz and megahertz oscillations in dendritic-somatic microtubules regulate specific firings of distal axonal branches, causally modulating membrane and synaptic activities. The brain should be viewed as a scale-invariant hierarchy, with quantum and classical processes critical to consciousness and cognition originating in microtubules inside neurons.

Gauge-independent emission spectra and quantum correlations in the ultrastrong coupling regime of open system cavity-QED

Abstract A quantum dipole interacting with an optical cavity is one of the key models in cavity quantum electrodynamics (cavity-QED). To treat this system theoretically, the typical approach is to truncate the dipole to two levels. However, it has been shown that in the ultrastrong-coupling regime, this truncation naively destroys gauge invariance. By truncating in a manner consistent with the gauge principle, we introduce master equations for open systems to compute gauge-invariant emission spectra, photon flux rates, and quantum correlation functions which show significant disagreement with previous results obtained using the standard quantum Rabi model. Explicit examples are shown using both the dipole gauge and the Coulomb gauge.

Realization of quantum dipoles in triangular lattice crystalBa3Yb(BO3)3

We investigate the thermodynamic properties of the ytterbium-based triangular lattice compound ${\mathrm{Ba}}_{3}\mathrm{Yb}{(\mathrm{B}{\mathrm{O}}_{3})}_{3}$. The results demonstrate the absence of any long-range ordering down to 56 mK. Analysis of the magnetization, susceptibility, and specific heat measurements suggests that ${\mathrm{Ba}}_{3}\mathrm{Yb}{(\mathrm{B}{\mathrm{O}}_{3})}_{3}$ may realize an $S=\frac{1}{2}$ quantum dipole lattice, in which the dominant interaction is the long-range dipole-dipole coupling on the geometrically frustrated triangular lattice, and exchange interactions are subdominant or negligible.

Purcell radiative rate enhancement of label-free proteins with ultraviolet aluminum plasmonics

The vast majority of proteins are intrinsically fluorescent in the ultraviolet, thanks to the emission from their tryptophan and tyrosine amino-acid constituents. However, the protein autofluorescence quantum yields are generally very low due to the prevailing quenching mechanisms by other amino acids inside the protein. This motivates the interest to enhance the radiative emission rate of proteins using nanophotonic structures. Although there have been numerous reports of Purcell effect and local density of optical states control in the visible range using single dipole quantum emitters, the question remains open to apply these concepts in the UV on real proteins containing several tryptophan and tyrosine amino acids arranged in a highly complex manner. Here, we report the first complete characterization of the Purcell effect and radiative rate enhancement for the UV intrinsic fluorescence of label-free β-galactosidase and streptavidin proteins in plasmonic aluminum nanoapertures. We find an excellent agreement with a calibration performed using a high quantum yield UV fluorescent dye. Demonstrating and intensifying the Purcell effect is essential for the applications of UV plasmonics and the label-free detection of single proteins.

QSPR modelling for intrinsic viscosity in polymer–solvent combinations based on density functional theory

ABSTRACT Linear and nonlinear quantitative structure–property relationship (QSPR) models were developed based on a dataset with 65 polymer-solvent combinations. Seven quantum chemical descriptors, dipole moment, hardness, chemical potential, electrophilicity index, total energy, HOMO and LUMO orbital energies, were calculated with density functional theory at the B3LYP/6-31 G(d) level for polymers and solvents. Considering the strong correlation between intrinsic viscosity and weight, size, shape as well as topological structure of polymers and solvents, topological descriptors were also applied in this work. Meanwhile, the most appropriate polymer structure representation was investigated by considering 1–5 monomeric repeating units. The molecular descriptors were first screened by using the genetic algorithms-multiple linear regression (GA-MLR), with coefficient of determinations () of 0.78 and 0.83 for the training set and the prediction set, respectively. The support vector machine model (SVM) model based on the selected descriptors subset showed a value of 0.95 for the training set and 0.93 for the prediction set. All statistical results suggest that the established QSPR models have good predictability. Furthermore, a new test set obtained from the literature was used for further validation. The values were 0.81 for the MLR model and 0.90 for the SVM model.

Mode coupling and enhanced Kerr nonlinearity with multiple Rayleigh scatterers containing a single dipole quantum emitter surrounding a whispering-gallery microcavity

We theoretically investigate a cavity quantum electrodynamics system in which a high-Q whispering-gallery-mode microcavity interacts simultaneously with a dipole quantum emitter and multiple Rayleigh scatterers. The scatterers are used to induce and to control mode coupling between counterclockwise and clockwise propagating light fields, which interact with the dipole quantum emitter. We study the effect of mode coupling on the linear and nonlinear output characteristics of coherent photon transport in a tapered fiber waveguide coupling the microcavity. It is found that enhanced optical Kerr nonlinearity with high linear transmission rate can be achieved efficiently when the system parameters are tuned properly. The present results illustrate the potential to utilize mode coupling for enhancing optical Kerr nonlinearities and controlling the transmission of light.

Path-integral Monte Carlo simulations of quantum dipole systems in traps: Superfluidity, quantum statistics, and structural properties

We present extensive \textit{ab initio} path integral Monte Carlo (PIMC) simulations of two-dimensional quantum dipole systems in a harmonic confinement, taking into account both Bose- and Fermi-statistics. This allows us to study the nonclassical rotational inertia, which can lead to a negative superfluid fraction in the case of fermions [Phys. Rev. Lett. \textbf{112}, 235301 (2014)]. Moreover, we study in detail the structural characteristics of such systems, and are able to clearly resolve the impact of quantum statistics on density profiles and the respective shell structure. Further, we present results for a more advanced center-two particle correlation function [Phys. Rev. E \textbf{91}, 043104 (2015)], which allows to detect differences between Fermi- and Bose-systems that do not manifest in other observables like the density. Overall, we find that bosonic systems sensitively react to even small values of the dipole--dipole coupling strength, whereas such a weak interaction is effectively masked for fermions by the Pauli exclusion principle. In addition, the abnormal superfluid fraction for fermions is not reflected by the structural properties of the system, which are equal to the bosonic case even though the moments of inertia diverge from each other. Lastly, we have demonstrated that fermionic PIMC simulations of quantum dipole systems are feasible despite the notorious fermion sign problem, which opens up new avenues for future investigations in this field.

Strongly Correlated Molecular Magnet with Curie Temperature above 60 K

Summary Two-dimensional crystals with ferromagnetic ordering would lead to unprecedented possibilities for magnetic, magneto-optic, and magnetoelectric applications. However, long-range ferromagnetic ordering in two-dimensional van der Waals materials is strongly diminished by thermal fluctuation, while three-dimensional systems show the stiffness of magnetic ordering temperature to magnetic fields. Here, we report the discovery of intrinsic ferromagnetic ordering temperature of 60 K in an iron/tetracyanoquinodimethane layer via superconducting precursor. In such a molecular ferromagnet, an unprecedented control of ferromagnetic fluctuation temperature by ∼200% improvement is realized through magnetic fields. We demonstrate magnetodielectric coupling with a concomitant transition in magnetic ordering. A small magnetic field of 0.01 T enables an effective route to realize a sizable transition shift in magnetodielectric states. Stimulated by photoirradiation, it manifests a hidden metallic conducting state, declaring a metallic ferromagnet. The molecular ferromagnet and photoirradiation-induced hidden metallic phase present a “holy grail” in the field of molecular conducting magnets.

Photoluminescence of molecules near metal nanoparticles with a dielectric shell

The article discusses the issues of modifying the photoluminescence intensity of quantum dipole emitters (molecules, quantum dots (nanocryslalls)) located near metal spherical nanoparticles with a dielectric shell. It is shown that by specifying the optimal configuration of a nanoparticle with a shell and the position of the emitter, it is possible to create the conditions, under which an increase in the photoluminescence intensity can be greater than in the case of the same nanoparticle without a shell.

Polarity and Structure of Se-Esters of Diselenophosphinic Acids: Experimental and Theoretical Conformational Analysis in Solution

Conformational analysis of Se-esters of diselenophosphinic acids has been performed and their polarities have been determined using the methods of dipole moments and quantum chemistry (DFT [B3PW91/6-311++G(df,p)]+CPCM). In solution, the studied compounds exist as an equilibrium of several conformers with staggered gauche and trans- or eclipsed cis-orientation of the substituents relative to the P=Se bond. The presence of eclipsed cis-conformations is explained by the formation of intramolecular H⋯Se bonds involving the hydrogen atom of the Se-alkyl(benzyl) or phenyl substituents at the phosphorus atom and the selenium atom of the P=Se group.

Cross density of states and mode connectivity: Probing wave localization in complex media

We introduce the mode connectivity as a measure of the number of eigenmodes of a wave equation connecting two points at a given frequency. Based on numerical simulations of scattering of electromagnetic waves in disordered media, we show that the connectivity discriminates between the diffusive and the Anderson localized regimes. For practical measurements, the connectivity is encoded in the second-order coherence function characterizing the intensity emitted by two incoherent classical or quantum dipole sources. The analysis applies to all processes in which spatially localized modes build up, and to all kinds of waves.

Quantum dipole emitters in structured environments: a scattering approach: tutorial.

We provide a simple semi-classical formalism to describe the coupling between one or several quantum emitters and a structured environment. Describing the emitter by an electric polarizability, and the surrounding medium by a Green function, we show that an intuitive scattering picture allows one to derive a coupling equation from which the eigenfrequencies of the coupled system can be extracted. The model covers a variety of regimes observed in light-matter interaction, including weak and strong coupling, coherent collective interactions, and incoherent energy transfer. It provides a unified description of many processes, showing that different interaction regimes are actually rooted on the same ground. It can also serve as a basis for the development of more refined models in a full quantum electrodynamics framework.