Aharonov-Bohm Research Articles

Aharonov-Bohm effect on the generalized Dirac oscillator in a cosmic dislocation space-time

In this work, we investigate the spin-half relativistic particles described by the Dirac equation on the topological defect background induced by the cosmic string and torsion with an internal magnetic field. We derive the general expression of the generalized Dirac oscillator on the topological defect background and analyze the analogue of the Aharonov-Bohm effect for the Dirac oscillator with function considered as the Cornell potential, and we explain the influence of related parameters on the energy levels of the studied system.

Intratumoral Activation of 41BB Costimulatory Signals Enhances CD8 T Cell Expansion and Modulates Tumor-Infiltrating Myeloid Cells.

The activation of 41BB costimulatory signals by agonistic Abs enhances the expansion and function of tumor-infiltrating lymphocytes (TILs) for treating cancer patients with adoptive cell therapy. However, the impact of 41BB agonism is not limited to enhancing the activity of T cells, and the mechanism by which additional activation of this costimulatory axis in tumor-associated myeloid cells is poorly understood. In this study, we describe that the intratumoral administration of 41BB agonistic Abs led to increases in CD8 T cell infiltration followed by tumor regression in murine models. We found that granulocytes and monocytes rapidly replaced macrophages and dendritic cells in tumors following administration of anti-41BB Abs. Overall, myeloid cells from anti-41BB-treated tumors had an improved capacity to stimulate T cells in comparison with control-treated tumors. In human coculture systems, we demonstrated that the agonism of the 41BB-41BBL axis enhanced costimulatory signals and effector functions among APC and autologous TILs. Overall, these findings suggest that the effect of 41BB agonistic Abs are supported by additional costimulatory signals from tumor-associated myeloid cells,v leading to enhanced TIL expansion and function.

Gate-Modulated Quantum Interference Oscillations in Sb-Doped Bi2Se3 Topological Insulator Nanoribbon

Topological insulator nanoribbons (TI NRs) provide a useful platform to explore the phase-coherent quantum electronic transport of topological surface states, which is crucial for the development of topological quantum devices. When applied with an axial magnetic field, the TI NR exhibits magnetoconductance (MC) oscillations with a flux period of h/e, i.e., Aharonov-Bohm (AB) oscillations, and h/2e, i.e., Altshuler-Aronov-Spivak (AAS) oscillations. Herein, we present an extensive study of the AB and AAS oscillations in Sb doped Bi$_2$Se$_3$ TI NR as a function of the gate voltage, revealing phase-alternating topological AB oscillations. Moreover, the ensemble-averaged fast Fourier transform analysis on the Vg dependent MC curves indicates the suppression of the quantum interference oscillation amplitudes near the Dirac point, which is attributed to the suppression of the phase coherence length within the low carrier density region. The weak antilocalization analysis on the perpendicular MC curves confirms the idea of the suppressed coherence length near the Dirac point in the TI NR.

Three dimensional Green function in cylindrical coordinates: application to the Aharonov–Bohm effect of double arc-slits

The object of this paper is the generalization of the theoretical calculation of the probability density of finding a charged particle crossing the double arc-slit in the presence of the vector potential. The explicit derivations is carried out in cylindrical coordinates for the Green functions for the underlying problem corresponding to a particle in free magnetic field, for a quantized as well as a non-quantized flux. The discussion in this paper will be limited to the uniform wavefunction of each particle on the surfaces of double arc-slits.

Thermal Properties and Magnetic Susceptibility of Hellmann Potential in Aharonov–Bohm (AB) Flux and Magnetic Fields at Zero and Finite Temperatures

In this research work, the Hellmann potential is studied in the presence of external magnetic and AB flux fields within the framework of Schrodinger equation using the Nikiforov–Uvarov functional analysis method. The energy equation and wave function of the system are obtained in closed form. The effect of the fields on the energy spectra of the system is examined in detail. It is found that the AB field performs better than the magnetic field in its ability to remove degeneracy. Furthermore, the magnetization and magnetic susceptibility of the system were discussed at zero and finite temperatures. We evaluate the partition function and use it to evaluate other thermodynamic properties of the system such as magnetic susceptibility, $$ \chi_{\text{m}} \left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , Helmholtz free energy $$ F\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , entropy $$ S\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , internal energy $$ U\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ and specific heat $$ C_{v} \left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ . A comparative analysis of the magnetic susceptibility of the system at zero and finite temperatures shows a similarity in the behavior of the system. A straightforward extension of our results to three dimensions shows that the present result is consistent with what is obtained in the literature.

Aharonov\u2013Bohm superselection sectors

We show that the Aharonov–Bohm effect finds a natural description in the setting of QFT on curved spacetimes in terms of superselection sectors of local observables. The extension of the analysis of superselection sectors from Minkowski spacetime to an arbitrary globally hyperbolic spacetime unveils the presence of a new quantum number labelling charged superselection sectors. In the present paper, we show that this “topological” quantum number amounts to the presence of a background flat potential which rules the behaviour of charges when transported along paths as in the Aharonov–Bohm effect. To confirm these abstract results, we quantize the Dirac field in the presence of a background flat potential and show that the Aharonov–Bohm phase gives an irreducible representation of the fundamental group of the spacetime labelling the charged sectors of the Dirac field. We also show that non-Abelian generalizations of this effect are possible only on spacetimes with a non-Abelian fundamental group.

Adjustable Quantum Interference Oscillations in Sb-Doped Bi2Se3 Topological Insulator Nanoribbons.

Topological insulator (TI) nanoribbons (NRs) provide a platform for investigating quantum interference oscillations combined with topological surface states. One-dimensional subbands formed along the perimeter of a TI NR can be modulated by an axial magnetic field, exhibiting Aharonov-Bohm (AB) and Altshuler-Aronov-Spivak (AAS) oscillations of magnetoconductance (MC). Using Sb-doped Bi2Se3 TI NRs, we found that the relative amplitudes of the two quantum oscillations can be tuned by varying the channel length, exhibiting crossover from quasi-ballistic to diffusive transport regimes. The AB and AAS oscillations were discernible even for a 70 μm long channel, while only the AB oscillations were observed for a short channel. Analyses based on ensemble-averaged fast Fourier transform of MC curves revealed exponential temperature dependences of the AB and AAS oscillations, from which the circumferential phase-coherence length and thermal length were obtained. Our observations indicate that the channel length in a TI NR can be a useful control knob for tailored quantum interference oscillations, especially for developing topological hybrid quantum devices.

Discrete optical propagation in one-dimensional synthetic mesh lattice

Synthetic mesh lattice (SML) with temporally controlled potential is a versatile platform for realizing wave dynamics associated with physical areas of optics and quantum physics. Here, discrete optics in one-dimensional synthetic photonic lattice is investigated systematically, in which the light behavior is highly analogous to that in evanescently coupled one-dimensional discrete waveguides. Such a synthetic dimension is constructed with position-dependent periodic effective gauge fields based on the Aharonov–Bohm effect arising from the phase accumulation of the fiber loops. By tuning the phase accumulation and coupling coefficient of the coupler, the band translation and gap property can be modulated, which further results in the impulse and tailored Gaussian wave packet responses as well as Talbot recurrences. In addition, Bloch oscillations and Anderson localization can also be obtained when the phase accumulations are linearly changed and weakly modulated in a random manner, respectively. The periodic effective gauge fields configuration in our protocol enables SML to be a research platform for one-dimensional dynamically modulated elements or even non-Hermitian waveguides.

Universal Voltage Fluctuations in Disordered Superconductors.

The Aharonov-Casher effect is the analogue of the Aharonov-Bohm effect that applies to neutral particles carrying a magnetic moment. This effect can be manifested by vortices or fluxons flowing in trajectories that encompass an electric charge. These vortices have been predicted to result in a persistent voltage that fluctuates for different sample realizations. Here, we show that disordered superconductors exhibit reproducible voltage fluctuation, which is antisymmetrical with respect to the magnetic field, as a function of various parameters such as the magnetic field amplitude, field orientations, and gate voltage. These results are interpreted as the vortex equivalent of the universal conductance fluctuations typical of mesoscopic disordered metallic systems. We analyze the data in the framework of random matrix theory and show that the fluctuation correlation functions and curvature distributions exhibit behavior that is consistent with Aharonov-Casher physics. The results demonstrate the quantum nature of the vortices in highly disordered superconductors, both above and below T_{c}.

Electron diffraction by vacuum fluctuations

Vacuum fluctuations are known to produce electron diffraction leading to decoherence and self-interference. These effects have so far been studied as either an extension of the Aharonov–Bohm effect in front of a planar perfect conductor or through path integral analysis. Here, we present a simpler, general, and rigorous derivation based on a direct solution of the quantum electrodynamic aloof interaction between the electron and a material structure in the temporal gauge. Our approach allows us to study dissipative media, for which we show examples of electron wave function shaping due to the interaction with real-metal surfaces. We further present a proof of the relation between the phase associated with vacuum fluctuations and the Aharonov–Bohm effect produced by the image self-interaction that is valid for arbitrary geometries. Besides their fundamental interest, our results could be useful for on-demand patterning of electron beams with potential application in nondestructive nanoscale imaging and spectroscopy.

Aharonov–Bohm effect for bound states in the cosmic string spacetime in the context of rainbow gravity

We explore a scenario of the general relativity determined by the framework of the rainbow gravity with the purpose of searching for analogues of the Aharonov-Bohm effect. By focusing on the confinement of the Dirac field and the scalar field to a hard-wall confining potential in a modified background of the cosmic string spacetime, we examine the effects of the rainbow gravity and the topology of the cosmic string spacetime. Then, we compare each spectrum of energy with the cases where the rainbow gravity is absent.

Quantum dynamics of spin-0 scalar particle with a uniform magnetic field and scalar potential in spinning cosmic string space-time and AB-effect

The relativistic quantum dynamics of a spin-0 scalar massive charged particle with an external uniform magnetic field including a magnetic quantum flux in a spinning cosmic string with a scalar potential is studied. We compute the energy eigenvalues and eignfunctions and analyze a relativistic analogue of the Aharonov-Bohm (AB) effect for bound states.

Gravity-Induced Geometric Phases and Entanglement in Spinors and Neutrinos: Gravitational Zeeman Effect

We show Zeeman-like splitting in the energy of spinors propagating in a background gravitational field, analogous to the spinors in an electromagnetic field, otherwise termed the Gravitational Zeeman Effect. These spinors are also found to acquire a geometric phase, in a similar way as they do in the presence of magnetic fields. However, in a gravitational background, the Aharonov-Bohm type effect, in addition to Berry-like phase, arises. Based on this result, we investigate geometric phases acquired by neutrinos propagating in a strong gravitational field. We also explore entanglement of neutrino states due to gravity, which could induce neutrino-antineutrino oscillation in the first place. We show that entangled states also acquire geometric phases which are determined by the relative strength between gravitational field and neutrino masses.

Relativistic Analogues of the Aharonov-Bohm Effect and the Landau Quantization with the Lorentz Symmetry Violation Determined by Azimuthal Electric Fields and a Fixed Vector Field

We analyse the behaviour of the Dirac field under the effects of the violation of the Lorentz symmetry determined by a fixed time-like vector background and azimuthal electric fields. We show, from the interaction of the Dirac particle with an azimuthal electric field (proportional to the inverse of the radial distance) and the fixed time-like vector field, that analogues of the Aharonov-Bohm effect can be obtained. Besides, from the interaction of the Dirac field with an azimuthal electric field (proportional to the radial distance) and the fixed time-like vector field, therefore, a relativistic analogue of the Landau quantization can be achieved.

Effects of rotation on a scalar field in a Kaluza–Klein theory

We have investigated the effects of rotation on a scalar field subject to the Aharonov–Bohm effect, an effect arising from a particular and possible scenario, from the theoretical point of view, of the Kaluza–Klein theory. Through the boundary condition induced by the non-inertial effect, for a particular case, we analyze a scalar particle in a region bounded by the cylindrical surfaces and under the effects of a hard-wall confining potential. In addition, a scalar particle with position-dependent mass interacting with the Coulomb-type potential. Then, in this scenario of the Kaluza–Klein theory in a uniformly rotating frame, we analyze the Klein–Gordon oscillator. In all cases an effect analogous to the Sagnac effect is observed on the relativistic energy levels determined analytically.

Association of anti-NR2 and U1RNP antibodies with neurotoxic inflammatory mediators in cerebrospinal fluid from patients with neuropsychiatric systemic lupus erythematosus

Autoantibodies (auto Abs) and inflammatory mediators (IMs) in cerebrospinal fluid (CSF) may be involved in the pathogenesis of neuropsychiatric systemic lupus erythematosus (NPSLE). It is suggested that anti-N-methyl D-aspartate receptor NR2 subunit (NR2) Ab can develop NP manifestation after blood-brain barrier (BBB) abruption. We also reported the association between NPSLE and CSF anti-U1RNP Ab. In the present study, combined effects of CSF anti-NR2 and anti-U1RNP Abs on IMs in patients with NPSLE were examined. CSF samples were collected from 69 patients with NPSLE and 13 non-NPSLE controls. CSF anti-NR2 and anti-U1RNP Abs were determined using ELISA. Levels of IL-6, IL-8, and monokine induced by IFN-γ (MIG) in CSF were measured by quantitative multiplex cytokine analysis. CSF IL-6 levels were higher in CSF anti-NR2-positive than in CSF anti-NR2-negative patients (p = 0.003) and non-NPSLE controls (p = 0.015) and were positively correlated with anti-NR2 titer (r = 0.42). CSF IL-8 levels were higher in CSF anti-U1RNP-positive than in CSF anti-U1RNP-negative patients (p = 0.041). CSF MIG levels were more elevated in CSF anti-NR2-positive (p = 0.043) and anti-U1RNP-positive patients (p = 0.029) than in non-NPSLE controls. Additionally, in double positive (DP; both anti-NR2 and U1RNP Ab positive) group, CSF IL-6 and MIG levels were significantly higher than in the double negative (DN; both anti-NR2 and U1RNP Ab negative) group. However, combined effect of both Abs on IM elevation and clinical manifestation was not clear. CSF anti-NR2 and anti-U1RNP Abs have different effects on the elevation of CSF IM levels in patients with NPSLE. Additional effect of anti-U1RNP Abs on anti-NR2 Ab-mediated NP manifestation, however, was not recognized in our study.

Enhancement of Anti-allergic Effect of Diethylcarbamazine Citrate in Asthmatic Mouse Model: Testing of Anti-drug Antibodies and Quercetin.

Diethylcarbamazine citrate (DEC) is known as an effective treatment for bronchial asthma because of its ability to reduce eosinophil trafficking to the lung tissue. The current study aimed to potentiate the anti-allergic effect of the drug by passive immunization of the asthmatic model with anti-DEC antibody or prior treatment with quercetin (Qur). Eight mice groups were categorized into control, the model of lung asthma, treated with DEC, passively immunized with anti(α)-bovine serum albumin Ab, anti-DEC Ab, prior exposure to 10, 20, or 40 mg Qur/Kg. b.wt. Both eosinophil peroxidase (EPO) and eotaxin2 in the lung tissues were performed. Serum levels of cytokines, bronchoalveolar lavage fluid (BALF) IgE, rabbit anti-bovine serum albumin (anti-BSA), and DEC IgG in lung tissue homogenates were assayed by ELISA. Regarding the effect of anti-DEC Ab and Qur on DEC-induced recovery of histopathological alterations showed that the Ova group had peri-bronchial hyperplasia, mononuclear leukocyte infiltration, thickening in the wall of alveoli, and congested blood vessels. However, the reduction of inflammatory cells and thickened alveolar walls was dependent on the Qur dose. Qur40 enhanced the anti-allergic effect of DEC. Moreover, the present data revealed high levels of Th2 cytokines (IL-4 and IL-5) and IgE in the Ova group. An increased leukocyte infiltration/thickening of the alveolar wall and lung tissue EPO/eotaxin2 were also observed. Qur-40 could show an enhancement effect on DEC for the reduction of IL-4, IL-5, IgE, EPO, and eotaxin 2. Consequently, the IFN-γ/IL-4 ratio was increased. Qur at 40 mg/Kg could be recommended to enhance the DEC effect suggesting a novel approach for treatment.

The generalized Klein–Gordon oscillator in a cosmic space-time with a space-like dislocation and the Aharonov–Bohm effect

In the present work, we investigated the quantum behavior of a charged particle that is under the effect of a uniform magnetic external field. We assumed that space-time has a space-like dislocation with an internal magnetic flux. We examined two different types of potential energies that are known as the pseudo harmonic and Cornell type potential energies, with the nonminimal coupling. We observed the Aharonov-Bohm effect in both cases. We extended the analysis on the energy spectrum functions to the different limits.

Noninertial and spin effects on the 2D Dirac oscillator in the magnetic cosmic string background

In this work, we analyze the influence of noninertial and spin effects on the dynamics of the 2D Dirac oscillator in the magnetic cosmic string background. To model this background, we consider a uniform magnetic field, the Aharonov–Bohm effect, and a parameter $$\eta $$ generated by a cosmic string. Posteriorly, we determine the bound-state solutions of the system: the Dirac spinor and the relativistic energy spectrum. We verified that this spinor is written in terms of the generalized Laguerre polynomials and this spectrum depends on the effective quantum number $$N_r$$ , angular velocity $$\Omega $$ and parameter s associated to the noninertial and spin effects, magnetic flux $$\Phi $$ , cyclotron frequency $$\omega _c$$ , zero-point energy $$E_0$$ , and on the deficit angle $$\eta $$ . In particular, we note that besides this spectrum to be a periodic function and asymmetric, its values infinitely increase when $$\eta \rightarrow 0$$ or $$N_r=\omega _c=\Omega \rightarrow \infty $$ . We also note that the energies of the antiparticle with spin down are larger than of the particle with spin up or down. In the nonrelativistic limit, we get the Schrodinger–Pauli oscillator with two types of couplings: the spin-orbit coupling and the spin-rotation coupling, and two Hamiltonians: one quantum harmonic oscillator-type and other Zeeman-type. Finally, we compare our results with other works, where we verified that our problem generalizes some particular cases of the literature when $$\Omega $$ , $$\omega _c$$ , $$\Phi $$ , s or $$\eta $$ are excluded from the system.

The Usefulness of Anti-acetylcholine Receptor Binding Antibody Testing in Diagnosing Ocular Myasthenia Gravis.

Anti-acetylcholine receptor antibody (AChR-Abs) testing is a safe and simple ancillary method for confirming the diagnosis of myasthenia gravis. Despite the test's high sensitivity (85%-90%) for generalized myasthenia gravis, AChR-Abs testing has been reported to have a low sensitivity 44%-66% for ocular myasthenia gravis (OMG). The aim of the study is to assess the effectiveness of AChR binding Abs testing for diagnosing OMG by evaluating the test's sensitivity, specificity, positive predictive value, and negative predictive value. A retrospective chart review on 114 OMG suspects who presented to the emergency department of a tertiary eye center in Victoria, Australia, was completed. The patients presented with diplopia alone, ptosis alone, or the combination of diplopia and ptosis. All participants were followed up longitudinally in the neuro-ophthalmology outpatient clinics for the average of 2.8 months, where they have received AChR binding testing. The final diagnosis was only given to the patients who either were seropositive for AChR binding Abs and had a high clinical suspicion of OMG, or the patient who was seronegative for AChR binding Abs but was regarded as likely to have OMG clinically and responded to the diagnostic treatments (pyridostigmine bromide and immunosuppressant therapy). The sensitivity of AChR binding Abs testing in diagnosing OMG was higher (80%; 95% confidence interval [CI], 51.91%-95.67%) than previously reported (44%-66%). AChR binding Abs testing also had a high specificity (98.99%; 95% CI, 94.50%-99.97%) and positive predictive value (92.31%; 95% CI, 62.68%-98.85%). The study suggests the higher utility of the AChR binding Abs testing in diagnosing OMG due to its high sensitivity, specificity, and positive predictive value.