Aharonov-Bohm Research Articles

Local Description of the Aharonov–Bohm Effect with a Quantum Electromagnetic Field

In the seminal works from Santos and Gozalo [Europhys. Lett. $\mathbf{45}$, 418 (1999)] and Marletto and Vedral [Phys. Rev. Lett. $\mathbf{125}$, 040401 (2020)], it is shown how the Aharonov-Bohm effect can be described as the result of an exchange of virtual photons between the solenoid and the quantum charged particle along its propagation through the interferometer, where both the particle and the solenoid interact locally with the quantum electromagnetic field. This interaction results in a local and gauge-independent phase generation for the particle propagation in each path of the interferometer. Here we improve the cited treatments by using the quantum electrodynamics formalism in the Lorentz gauge, with a manifestly gauge-independent Hamiltonian for the interaction and the presence of virtual longitudinal photons. Only with this more complete and gauge-independent treatment it is possible to justify the acquired phases for interferometers with arbitrary geometries, and this is an advantage of our treatment. We also extend the results to the electric version of the Aharonov-Bohm effect. Finally, we propose an experiment that could test the locality of the Aharonov-Bohm phase generation.

Relativistic Landau quantization in the spiral dislocation spacetime

We analyse the interaction of a relativistic electron with a uniform magnetic field in the spiral dislocation spacetime. We show that analytical solutions to the Dirac equation can be obtained, where the spectrum of energy corresponds to the relativistic Landau levels. We also analyse the influence of the spiral dislocation on the relativistic Landau levels by showing that there exists an analogue of the Aharonov–Bohm effect for bound states.

Non-Hermitian Aharonov-Bohm effect in the quantum ring

We investigate the topological properties, energy spectrum, and persistent currents of a non-Hermitian ring with anti-Hermitian hopping terms. It is demonstrated that the anti-Hermitian hopping can effectively induce a synthetic gauge field. As the magnetic flux of the synthetic gauge field threads through the ring, the non-Hermitian system exhibits an Aharonov-Bohm effect. For the case of a non-Hermitian ring in the topological phase, the system, having an energy spectrum structure with a real gap, supports an imaginary persistent current. For the trivial case, a non-Hermitian system with an imaginary gap supports a real persistent current. Furthermore, we also investigate the transport property of a non-Hermitian Aharonov-Bohm ring connected by two semi-infinite leads. We find that the transmission coefficient shows the Aharonov-Bohm quantum oscillation as a function of the synthetic gauge field.

Aharonov-Bohm effect in graphene-based Fabry–Pérot quantum Hall interferometers

Aharonov-Bohm effect in graphene-based Fabry–Pérot quantum Hall interferometers

Effect of the Electric and Magnetic Fields with Aharonov–Bohm Flux Field in Quantum Dots

This paper has solved the nonrelativistic equation with the external uniform electric potential and magnetic and Aharonov–Bohm (AB) fields in a dot. We have obtained the three-term recurrence relation for the expansion coefficients using the series method. In continuing, we have found two different conditions. Then, using the obtained conditions, we have calculated the energy eigenvalues and eigenfunction. We have then obtained the main thermodynamic quantities such as the free energy, mean energy, entropy, specific heat, magnetization and persistent currents for our system. Also, we extended the calculations to an interaction-free [Formula: see text]-body system. The obtained analytic results are compared with other results, and some of the obtained results are discussed, too.

Generalized Klein–Gordon oscillator with a uniform magnetic field under the influence of Coulomb-type potentials in cosmic string space–time and Aharonov–Bohm effect

We solve a generalized Klein–Gordon oscillator (KGO) in the presence of a uniform magnetic field including quantum flux under the effects of scalar and vector potentials of Coulomb types in the static cosmic string space–time. We obtain the energy and corresponding eigenfunctions, and analyze a relativistic analogue of the Aharonov–Bohm effect for bound states.

A pure geometric approach to the Aharonov–Bohm effect

This article represents a possible geometric interpretation of the Aharonov–Bohm (A–B) effect. We presented a new curve in the context of Einstein–Maxwell geometry, using the Bazanski approach. In the context of the geometrization philosophy, this curve can be used as an equation of motion of a charged test particle in a combined gravitational and electromagnetic field. The new equation of motion obtained contains two extra terms more than the geodesic equation. The first contains the electromagnetic field strength, while the second term gives rise to the electromagnetic potential. Both terms represent forces affecting the acceleration of the moving charged particle in the field mentioned above. The second term gives rise to the A–B effect. Linearization of the new equation gives more physical meaning to the extra terms obtained.

The rovibrational Aharonov-Bohm effect.

Another manifestation of the Aharonov-Bohm effect is introduced to chemistry, in fact to nuclear quantum dynamics and high-resolution molecular spectroscopy. As demonstrated, the overall rotation of a symmetric-top molecule influences the dynamics of an internal vibrational motion in a way that is analogous to the presence of a solenoid carrying magnetic flux. To a good approximation, the low-energy rovibrational energy-level structure of the quasistructural molecular ion H+5 can be understood entirely in terms of this effect.

Circular charge and spin currents in a spatially varying Rashba ring in presence of Aharonov-Bohm flux

We investigate magnetic response in a single-channel mesoscopic ring, subjected to Aharonov- Bohm (AB) flux, in presence of spatially varying Rashba spin-orbit (SO) coupling. Simulating the ring system in a tight-binding framework we calculate both charge and spin currents and discuss the interplay between AB flux and SO coupling on these currents. Some anomalous patterns are exhibited following the energy spectrum. Our analysis can be utilized to study the magnetic response in similar kind of spatially varying SO coupled systems and helps us to probe fascinating operations.

Energy spectra and magnetic properties of diatomic molecules in the presence of magnetic and AB fields with the inversely quadratic Yukawa potential

Within the framework of non-relativistic quantum mechanics, the inversely quadratic Yukawa potential is investigated in the presence of external magnetic and Aharonov–Bohm (AB) fields. The Schrodinger equation is solved via the Nikiforov–Uvarov functional analysis (NUFA) method, and the obtained energy eigenvalues are discussed. It is shown that the presence of the magnetic and AB fields removes the degeneracy. The partition function of the system and the thermodynamic properties of the system such as Helmholtz free energy, entropy, internal energy, specific heat and the magnetization and magnetic susceptibility of the system are calculated in detail. The magnetic properties of the QYP in the presence of the magnetic and AB fields are also discussed. The variation of the magnetic field as a function of temperature plays an importance role in understanding of many quantum systems in physics and chemistry

The role of anti-elastin antibodies in a mouse model of asthma.

The role of anti-elastin antibody (Ab) in the lung is unclear, although they may be involved in chronic obstructive pulmonary disease (COPD). Recently, increased anti-elastin Ab levels were reported in asthma. To elucidate the role of anti-elastin Ab in asthma, we created a murine asthma model. Anti-elastin Ab in the airway was neutralized by intratracheal administration of elastin peptide, and the inhibitory effects of anti-elastin Ab on airway remodeling were evaluated. BALB/c mice were immunized with ovalbumin (OVA) on days 0 and 14. After immunization, the mice received booster OVA via inhalation twice per week for 9 weeks, and bronchoalveolar lavage fluid (BALF) and lung tissues were evaluated. In lung tissues, airway remodeling occurred after 9 weeks of OVA sensitization. Peak levels of anti-elastin Ab and eosinophils in BALF were detected after 3 weeks of OVA sensitization. Anti-elastin Ab and eosinophil levels in BALF were significantly reduced after 3 weeks by the neutralization of anti-elastin Ab. Peak transforming growth factor-β1 levels in BALF were detected at 3 weeks after OVA sensitization and were significantly reduced by the neutralization of anti-elastin Ab. Airway remodeling in lung tissues was also significantly inhibited by the neutralization of anti-elastin Ab. In our murine asthma model, anti-elastin Ab was recruited to the airway by OVA-induced allergic inflammation. Airway remodeling was inhibited by the neutralization of anti-elastin Ab. Anti-elastin Ab may contribute to the progression of airway remodeling.

Analogue of Aharonov–Bohm Effect in the Presence of a Magnetic Field Under the Influence of Coulomb-type Potentials in Topological Defect Space-time

We solve the Klein–Gordon equation subject to a homogeneous magnetic field including a quantum flux under the influence of a scalar and vector potential of Coulomb types in a cosmic string space-time, and analyze the relativistic analogue of the Aharonov–Bohm effect for bound states.

Dissipative Dynamics and Uncertainty Measures of a Charged Oscillator in the Presence of the Aharonov-Bohm Effect

We analyze the effects of dissipation in a charged oscillator in the presence of the Aharonov-Bohm effect by using time-dependent mass (m(t)) Hamiltonians. We consider two different models for the dissipative Hamiltonian and analyze the uncertainties (Δr and Δp) and the quantum mechanical expectation value of energy (⟨E⟩) in terms of time (t), damping parameters and flux parameter (v). For the Caldirola-Kanai model, we observe that the flux parameter v decreases the energy dissipation in a quantum dot for a certain range of t.

Twist effects on quantum vortex defects

We demonstrate that on a quantum vortex in Bose-Einstein condensates can form a new, central phase singularity. We define the twist phase for isophase surfaces and show that if the injection of a twist phase is global this phenomenon is given by an analog of the Aharonov-Bohm effect. We show analytically that the injection of a twist phase makes the filament unstable, that is the GP equation is modified by a new term that makes the Hamiltonian non-Hermitian. Using Kleinert’s theory for multi-valued fields we show that this instability is compensated by the creation of the second vortex, possibly linked with the first one.

Layer Pseudospin Dynamics and Genuine Non-Abelian Berry Phase in Inhomogeneously Strained Moiré Pattern.

Periodicity of long wavelength moiré patterns is very often destroyed by the inhomogeneous strain introduced in fabrications of van der Waals layered structures. We present a framework to describe massive Dirac fermions in such distorted moiré pattern of transition metal dichalcogenides homobilayers, accounting for the dynamics of layer pseudospin. In decoupled bilayers, we show two causes of in-plane layer pseudospin precession: By the coupling of layer antisymmetric strain to valley magnetic moment; and by the Aharonov-Bohm effect in the SU(2) gauge potential for the case of R-type bilayer under antisymmetric strain and H-type under symmetric strain. With interlayer coupling in the moiré, its interplay with strain manifests as a non-Abelian gauge field. We show a genuine non-Abelian Aharonov-Bohm effect in such field, where the evolution operators for different loops are noncommutative. This provides an exciting platform to explore non-Abelian gauge field effects on electron, with remarkable tunability of the field by strain and interlayer bias.

Gravitomagnetism in the Lewis cylindrical metrics

The Lewis solutions describe the exterior gravitational field produced by infinitely long rotating cylinders, and are useful models for global gravitational effects. When the metric parameters are real (Weyl class), the exterior metrics of rotating and static cylinders are locally indistinguishable, but known to globally differ. The significance of this difference, both in terms of physical effects (gravitomagnetism) and of the mathematical invariants that detect the rotation, remain open problems in the literature. In this work we show that, by a rigid coordinate rotation, the Weyl class metric can be put into a ‘canonical’ form where the Killing vector field ∂ t is time-like everywhere, and which depends explicitly only on three parameters with a clear physical significance: the Komar mass and angular momentum per unit length, plus the angle deficit. This new form of the metric reveals that the two settings differ only at the level of the gravitomagnetic vector potential which, for a rotating cylinder, cannot be eliminated by any global coordinate transformation. It manifests itself in the Sagnac and gravitomagnetic clock effects. The situation is seen to mirror the electromagnetic field of a rotating charged cylinder, which likewise differs from the static case only in the vector potential, responsible for the Aharonov–Bohm effect, formally analogous to the Sagnac effect. The geometrical distinction between the two solutions is also discussed, and the notions of local and global staticity revisited. The matching in canonical form to the van Stockum interior cylinder is also addressed.

Probing quantum coherence at a distance and Aharonov-Bohm nonlocality

In a standard interferometry experiment, one measures the phase difference between two paths by recombining the two wave packets on a beam-splitter. However, it has been recently recognized that the phase can also be estimated via local measurements, by using an ancillary particle in a known superposition state. In this work, we further analyse these protocols for different types of particles (bosons or fermions, charged or uncharged), with a particular emphasis on the subtleties that arise when the phase is due to the coupling to an abelian gauge field. In that case, we show that the measurable quantities are spacetime loop integrals of the 4-vector potential, enclosed by two identical particles or by a particle-antiparticle pair. Furthermore, we generalize our considerations to scenarios involving an arbitrary number of parties performing local measurements on a general charged fermionic state. Finally, as a concrete application, we analyse a recent proposal by Marletto and Vedral (arXiv:1906.03440) involving the time-dependent Aharonov-Bohm effect.

Magnetic field controlled topological transitions of the spin field in quantum rings with spin orbit couplings

The spin fields of the ground state of the two-dimensional quantum rings with Rashba and Dresselhaus spin-orbit couplings are studied and compared with our analysis of the one-dimensional model. The topological charge of the spin field varies periodically due to the step-like change of the angular momentum with an increase of the magnetic field which is perpendicular to the ring. We also demonstrate the cases where the one-dimensional model is invalid or unreliable for a relatively wide ring, by comparing with the reliable numerical results of the two-dimensional model. As a result, the period of the topological transition can be biased from the period of the Aharonov-Bohm effect. Moreover, in a non-symmetric quantum ring where a non-magnetic impurity is located, the density and the spin textures of the single-electron ground state jointly make a dramatic change comparing with the one-dimensional model. Even higher topological charge ±2 of the spin field at single-electron level can be achieved by tuning the magnetic field, which indicates a great advantage over other systems in potential applications.

Spin-0 scalar particle interacts with scalar potential in the presence of magnetic field and quantum flux under the effects of KKT in 5D cosmic string spacetime

In this paper, we study a relativistic quantum dynamics of spin-0 scalar particle interacts with scalar potential in the presence of a uniform magnetic field and quantum flux in background of Kaluza–Klein theory (KKT). We solve Klein–Gordon equation in the considered framework and analyze the relativistic analogue of the Aharonov–Bohm effect for bound states. We show that the energy levels depend on the global parameters characterizing the spacetime, scalar potential and the magnetic field which break their degeneracy.

Cognitive status, brain amyloid pathology, and neurodegeneration are associated with altered white matter microstructure

AbstractBackgroundBrain amyloid (AB) and neurodegeneration (assessed using PET and MRI) are key AD pathology biomarkers, particularly during transitions from cognitively unimpaired (CU) to cognitively impaired (CI) states. Importantly, the role of brain white matter microstructural measures in these changes, such as those derived from neurite orientation dispersion and density imaging (NODDI), are poorly understood. We explored roles of cognitive status, brain amyloid pathology, and neurodegeneration on NODDI Free Water (FW), a potential neuroinflammation biomarker.MethodParticipants enrolled in the Wake Forest Alzheimer’s Disease Research Center (ADRC) Clinical Core cohort (N=74, Table 1) underwent neuropsychological assessment, T1/NODDI MRI, and PiB PET. Participants were adjudicated as cognitively impaired (MCI or AD) or unimpaired using NIA‐AA criteria. T1 MRI were processed (FreeSurfer v5.3) to generate regions of interest (ROIs). An “AD‐signature” cortical thickness value was calculated, and thresholded to classify participants as neurodegeneration‐positive (N+) or ‐negative (N‐). A set of AD‐sensitive cortical ROIs was used to extract mean PET signal, which was thresholded to adjudicate AB positivity (AB‐/AB+). NODDI was processed to yield parameter maps using AMICO; mean isotropic volume fraction (FW) was calculated over a set of white matter tract ROIs. A two‐way ANOVA/ANCOVA (covariates: age, sex, education) assessed effects of neurodegeneration and AB on FW (N+/N‐ x AB+/AB‐), and a two‐way ANOVA/ANCOVA assessed effects of cognitive impairment and AB on FW (CU/CI x AB+/AB‐).ResultWe first examined effects of neurodegeneration and AB on NODDI FW. We found a significant main effect of neurodegeneration (p=.042), such that N+ had higher FW; this was marginal after adjustment (p=.07). We also observed a significant main effect of AB (p<.001; adjusted p=.012), with AB+ having higher FW. There was no significant interaction. We next explored how cognitive status and AB interacted on FW. We found a significant main effect of cognitive impairment, with CI having higher FW (p=.018; adjusted p=.013). We also found an interaction between diagnosis and AB (p=.037; adjusted p=.044) such that among AB+ individuals, presence of CI related to increased FW (Figure 1).ConclusionNODDI FW increases were significantly affected by the presence of neurodegeneration, AB positivity, and cognitive impairment.