Aharonov-Bohm Research Articles

Manipulating Majorana qubit states without braiding

We propose a scheme to manipulate the Majorana qubit states other than braiding. By utilizing electron transport through Majorana zero modes and tuning the magnetic flux in the setup, the aim of Majorana qubit state manipulation can be fulfilled. The principal part in the setup is an Aharonov-Bohm (AB) interferometer consisting of two topological superconducting chains (TSCs) connected to two leads. We obtain the exact master equation as well as its solution and study the general properties of the real-time dynamics of the Majorana qubit states. The parity of the Majorana qubit state can be almost perfectly polarized by tuning the bias and can also be flipped by switching the sign of the cross couplings between the TSCs and the leads. Moreover, the qubit coherence shows a phase rigidity due to the intrinsic particle-hole symmetry of the Majorana AB interferometer, which is different from that in the double-quantum-dot AB interferometers without topological properties.

Phonon-induced anomalous gauge potential for photonic isolation in frequency space

Photonic gauge potentials are crucial for manipulating charge-neutral photons like their counterpart electrons in the electromagnetic field, allowing the analogous Aharonov–Bohm effect in photonics and paving the way for critical applications such as photonic isolation. Normally, a gauge potential exhibits phase inversion along two opposite propagation paths. Here we experimentally demonstrate phonon-induced anomalous gauge potentials with noninverted gauge phases in a spatial-frequency space, where near-phase-matched nonlinear Brillouin scatterings enable such unique direction-dependent gauge phases. Based on this scheme, we construct photonic isolators in the frequency domain permitting nonreciprocal propagation of light along the frequency axis, where coherent phase control in the photonic isolator allows switching completely the directionality through an Aharonov–Bohm interferometer. Moreover, similar coherent controlled unidirectional frequency conversions are also illustrated. These results may offer a unique platform for a compact, integrated solution to implement synthetic-dimension devices for on-chip optical signal processing.

What can we learn from the conformal noninvariance of the Klein–Gordon equation?

It is well known that the Klein–Gordon equation in curved spacetime is conformally noninvariant, both with and without a mass term. We show that such a noninvariance provides nontrivial physical insights at different levels, first within the fully relativistic regime, then in the nonrelativistic regime leading to the Schrödinger equation, and then within the de Broglie–Bohm causal interpretation of quantum mechanics. The conformal noninvariance of the Klein–Gordon equation coupled to a vector potential is confronted with the conformal invariance of Maxwell’s equations in the presence of a charged current. The conformal invariance of the nonminimally coupled Klein–Gordon equation to gravity is then examined in light of the conformal invariance of Maxwell’s equations. Finally, the consequence of the noninvariance of the equation on the Aharonov–Bohm effect in curved space–time is discussed.

Nonlinear Topological Effects in Optical Coupled Hexagonal Lattice.

Topological physics in optical lattices have attracted much attention in recent years. The nonlinear effects on such optical systems remain well-explored and a large amount of progress has been achieved. In this paper, under the mean-field approximation for a nonlinearly optical coupled boson–hexagonal lattice system, we calculate the nonlinear Dirac cone and discuss its dependence on the parameters of the system. Due to the special structure of the cone, the Berry phase (two-dimensional Zak phase) acquired around these Dirac cones is quantized, and the critical value can be modulated by interactions between different lattices sites. We numerically calculate the overall Aharonov-Bohm (AB) phase and find that it is also quantized, which provides a possible topological number by which we can characterize the quantum phases. Furthermore, we find that topological phase transition occurs when the band gap closes at the nonlinear Dirac points. This is different from linear systems, in which the transition happens when the band gap closes and reopens at the Dirac points.

Rotating frame effects and potential on a relativistic scalar particle in Kaluza–Klein theory

The effects of uniform rotation on a relativistic scalar particle that interacts with a Cornell-type potential in background space–time described by the Kaluza–Klein theory are analyzed and the gravitational analogue of the Aharonov–Bohm effect is observed. Furthermore, linear confinement of a relativistic scalar particle was also discussed. We see a coupling between the angular velocity of the rotating frame [Formula: see text] and the angular momentum eigenvalue [Formula: see text] which shows the Sagnac-type effect.

Nonlinear regime for enhanced performance of an Aharonov–Bohm heat engine

Thermal transport and quantum thermodynamics at the nanoscale are nowadays garnering increasing attention, in particular, in the context of quantum technologies. Experiments relevant for quantum technology are expected to be performed in the nonlinear regime. In this work, we build on previous results derived in the linear response regime for the performance of an Aharonov–Bohm (AB) interferometer operated as a heat engine. In the nonlinear regime, we demonstrate the tunability, large efficiency, and thermopower that this mesoscopic quantum machine can achieve, confirming the exciting perspectives that this AB ring offers for developing efficient thermal machines in the fully quantum regime.

Energy spectrum of bilayer graphene with magnetic quantum structures studied using the Dirac equation

The electronic energy spectrum of bilayer graphene with a magnetic quantum dot (MQD) and a magnetic quantum ring (MQR) are investigated. The energy eigenvalues and wavefunctions of quasiparticle states are calculated analytically by solving decoupled fourth-order differential equations. For the MQD, in the case of a negative inner magnetic field, two peculiar characteristics of the eigenvalue evolution are found: (a) the energy eigenstates change in a stepwise manner owing to energy anticrossing and (b) the quantum states approach zero energy. For the MQR, there is an angular momentum transition of eigenvalue as the inner radius of the ring varies, and the Aharonov–Bohm effect is observed in the eigenvalue spectra for both positive and negative magnetic fields inside the inner radius.

Investigation of the Aharonov-Bohm and Aharonov-Casher topological phases for quantum entangled states

Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects are treated fully relativistically in 2+1 dimensions. The influences of the relevant geometric and topological phases on an entangled spin-1/2 system are studied. It is shown that for the AC case the correlation function of the Clauser-Horne-Shimony-Holt (CHSH) inequality for certain choices of the spin measurements depends on the AC phase explicitly.

Prognostic impact of proton pump inhibitors for immunotherapy in advanced urothelial carcinoma.

ObjectiveTo evaluate the effects of the concomitant use of proton pump inhibitors (PPIs) and/or antibiotics (Abs) on oncological outcomes in patients with advanced urothelial carcinoma.Patients and methodsWe retrospectively evaluated 155 patients with advanced urothelial carcinoma who were treated with immune checkpoint inhibitors (ICIs) between August 2015 and April 2021. The concomitant use of PPI or Abs was defined as any PPI or Abs administered within 30 days before ICI initiation and during ICI therapy. The primary outcomes were the effect of PPI and/or Abs use on the objective response rate (ORR) and immune‐related adverse events (irAEs). The secondary outcomes were the effects of PPI and/or Abs use on progression‐free survival (PFS) and overall survival (OS) after ICI therapy analyzed using the inverse probability of treatment weighting‐adjusted Cox regression analysis.ResultsOf the 155 patients enrolled in the study, 99 (64%) were PPI users and 56 (36%) Abs users. PPI users were associated with a significantly poorer ORR than non‐PPI users (41% vs. 20%, respectively), whereas Abs use was not significantly associated with changes in ORR. The rate of irAEs was not significantly associated with the use of PPIs or Abs. Multivariate inverse probability of treatment weighting‐adjusted Cox regression analysis revealed significantly poorer PFS and OS in PPI users than in non‐PPI users, whereas Abs use was not associated with poorer outcomes.ConclusionThe concomitant use of PPI may adversely affect oncological outcomes in patients with locally advanced or metastatic urothelial carcinoma treated with ICI therapy.

Aharonov-Casher and shielded Aharonov-Bohm effects with a quantum electromagnetic field

We use a covariant formalism that is capable of describing the electric and magnetic versions of the Aharonov-Bohm effect, as well as the Aharonov-Casher effect, through local interactions of charges and currents with the quantum electromagnetic field. By considering that only local interactions of a quantum particle with the quantum field can affect its behavior, we show that the magnetic Aharonov-Bohm effect must be present even if the solenoid generating the magnetic field is shielded by a perfect conductor, as experimentally demonstrated.

Super aggregated amphotericin B with a thermoreversible in situ gelling ophthalmic system for amoebic keratitis treatment

Acanthamoeba spp. are the causative agents of a sight-threatening infection of the cornea known as Acanthamoeba keratitis (AK). Amphotericin B - deoxycholate (AB) is used in the treatment of infectious keratitis, however, its topical administration has side effects as blepharitis, iritis, and painful instillation. In this context, the preheating of AB can decrease its toxicity by the formation of super aggregates (hAB). hAB associated with a thermoreversible in situ gelling ophthalmic system is a promising option due to the latter biocompatibility, low toxicity, and high residence time on the ocular surface. Our objective was to develop a topical ocular formulation of hAB for the treatment of AK. After heating at 70°C for 20 min, hAB was incorporated into a thermoreversible gelling system. The amebicidal activity of AB and hAB was evaluated against trophozoites and cysts of A. castellanii (ATCC 50492) and a regional clinical isolate (IC01). The results showed that the preheating of AB did not change the pharmacological action of the drug, with the amebicidal effect of AB and hAB under trophozoites and cysts of Acanthamoeba spp. The thermoreversible system remained stable, allowing the increase of drug retention time. For assessment of cytotoxicity, HUVEC (ATCC® CRL-1730) cells were challenged with AB and hAB for 48h. Cell viability was assessed, and hAB did not show cytotoxicity for HUVEC cells. As far as we know this was the first study that showed the preheated AB associated with a thermoreversible in situ gelling ophthalmic system as a promising system for topical ocular topical administration of hAB for AK therapy.

Topological confinement of vortices in two-flavor dense QCD

We find a novel confinement mechanism in the two-flavor dense quark matter proposed recently, that consists of the 2SC condensates and the P-wave diquark condensates of d-quarks. This quark matter exhibiting color superconductivity as well as superfluidity is classified into two phases; confined and deconfined phases of vortices. We establish that the criterion of the confinement is color neutrality of Aharonov-Bohm (AB) phases: vortices exhibiting color non-singlet AB phases are confined by the so-called AB defects to form color-singlet bound states. In the deconfined phase, the most stable vortices are non-Abelian Alice strings, which are superfluid vortices with fractional circulation and non-Abelian color magnetic fluxes therein, exhibiting color non-singlet AB phases. On the other hand, in the confined phase, these non-Abelian vortices are confined to either a baryonic or mesonic bound state in which constituent vortices are connected by AB defects. The baryonic bound state consists of three non-Abelian Alice strings with different color magnetic fluxes with the total flux canceled out connected by a domain wall junction, while the mesonic bound state consists of two non-Abelian Alice strings with the same color magnetic fluxes connected by a single domain wall. Interestingly, the latter contains a color magnetic flux in its core, but this can exist because of color neutrality of its AB phase.

Flux dependent current rectification in geometrically symmetric interconnected triple-dot Aharanov-Bohm interferometer

We propose and investigate a nonreciprocal performance of a triple-dot Aharonov-Bohm interferometer in the non-linear regime. We study the steady-state behavior of the nonequilibrium triple-dot Aharonov-Bohm (AB) interferometer using analytical tools and numerical simulations. Our simple setup includes noninteracting three quantum dots placed on the vertex of an equilateral triangle. Out of these three dots, two dots are coupled to two biased metallic leads at the same strength and the third one is connected with a probe that can mimics the elastic and inelastic scattering mechanisms. A magnetic flux Φ pierces the interferometer perpendicularly. We observe a magnetic-flux dependent current rectification induced by inelastic scattering by voltage probe in the nonlinear regime, but this rectification is absent in the linear regime. Our investigation reveals that the rectification for our 3-dots AB set up maximize when the inter-dot tunneling strength, t , matches with the hybridization strength, γ , between a dot and metallic lead. Downright, we can say that our study furnishes the working principles and rectification efficiency of a triple-dot AB interferometer. One can use this simple setup to design a nano-scale rectifier . • We demonstrate broken Onsager reciprocity relation in a triple dot Aharanov-Bohm interferometer model. • This exactly solvable model can unravel the interplay of quantum coherence and environmental decoherence effect.

Optical Analogue of the Aharonov-Bohm Effect in a Magneto-Active Medium

We study an optical analogue of the Aharonov-Bohm effect in a magneto-active medium containing a wire with current. It is shown that the phase shift between the light rays propagating around the wire is proportional to the current strength. The current acts as a magnetic flux in the conventional Aharonov-Bohm effect. Therefore the differential cross section of light scattering from the vortex of the magnetic field created by the linear current proves to be a periodic function of the current strength.

Unitary Theory of Quantum Mechanics and General Relativity

Essentially, in this paper we propose a new description of the quantum dynamics by two relativistic propagation wave packets, in the two conjugated spaces, of the coordinates and of the momentum. Compared to the Schrödinger-Dirac equation, which describes a free particle by a wave function continuously expanding in time, considered as the amplitude of a probabilistic distribution of this particle, the new equations describe a free particle as an invariant distribution of matter propagating in the two spaces, as it should be. Matter quantization arises from the equality of the integral of the matter density with the mass describing the dynamics of this density in the phases of the wave packets. In this description, the classical Lagrange and Hamilton equations are obtained as the group velocities of the two wave packets in the coordinate and momentum spaces. When to the relativistic Lagrangian we add terms with a vector potential conjugated to coordinates, as in the Aharonov-Bohm effect, and a scalar potential conjugated to time, we obtain the Lorentz force and the Maxwell equations as characteristics of the quantum dynamics. In this framework, the conventional Schrödinger-Dirac equations of a quantum particle in an electromagnetic field obtain additional terms explicitly depending on velocity, as is expected in the framework of relativistic theory. Such a particle wave function takes the form of a rapidly varying wave, with the frequency corresponding to the rest energy, modulated by the electric potential  where this particle is confined, the vector potential   of the electromagnetic radiation, and the gravitational potential. In the gravitational field of a black hole, the velocity of a quantum particle is directed to the Schwarzschild boundary from the outside and from the inside, without passing this boundary. When the very strong gravitational field of a large agglomeration of matter has spherical symmetry with a radius smaller than the Schwarzschild radius, the quantum particles in the central region are crushed up to quasi-uniform distributions of matter, exploding with velocities much larger than the light velocity, towards the Schwarzschild boundary, but decelerating in the gravitational field and reaching this boundary only in an infinite time. The matter of a black hole has the tendency to concentrate around the Schwarzschild boundary, with a radius proportional to its mass. In this framework, we believe that our universe is a huge black hole, with the explosion of its central matter as the Big Bang-inflation process, and an increasing radius on account of an absorption of matter from the Total Universe, where our universe has been formed. In a gravitational wave, the time-space interval in the first-order approximation is the product of a gravitational invariant including the amplitude tensor, and a coordinate invariant including the polarization vector. The gravitational invariant describes a rotation of the metric tensor around the direction of the propagation of this wave, with spin 2, as a gravitational quantum called graviton. The coordinate invariant describes a matter rotation with the spins ½ for Fermions, and 1 for Bosons. From the new dynamic equations, for a free particle in the coordinate and momentum spaces, we reobtain the two basic equations of the quantum field theory, but with a change of sign, and an additional term depending on momentum, to the rest mass as the eigenvalue of these equations. However, when these eigenvalues are eliminated, the wave function takes the form of a wave packet of spinors of the same form as in the conventional quantum field theory, with a normalization volume as the integral of the ratio of the energy to the rest energy, over the momentum domain which gives finite dimensions to the quantum particle, as a finite distribution of matter in the coordinate space.

Aharonov-Bohm effect in three-dimensional higher-order topological insulators

Hinge states are the hallmark of the 3D higher-order topological insulator(HOTI). Here, we show that chiral hinge states can be identified by the magnetic field induced Aharonov-Bohm(AB) oscillation of the electron conductance in the interferometer constructed by HOTI and normal metal. Unlike AB interferometer of 3D topological insulator(TI), we find that there are different AB oscillation frequencies for a given direction of magnetic field in 3D HOTI. And the oscillation frequencies are also strongly depending on the direction of magnetic field. The main conclusion in our work is that there exists a universal linear relation between different oscillation frequencies. Here, by constructing an interference model of hinge states loops, we show both analytically and numerically that the linear relation is fulfilled in the HOTI effective model. The four basic frequencies in the work are labeled as $\omega_x$, $\omega_y$, $\omega_{x+y}$, $\omega_{x-y}$ and the main linear relations we demonstrate here are $\omega_{x\pm y}=\omega_x \pm \omega_y$. These results provide an effective way for the identification of the chiral hinge states, and the oscillation signatures are stable with different sample size and bias.

Super-Resonant Transport of Topological Surface States Subjected to In-Plane Magnetic Fields.

Magnetic oscillations of Dirac surface states of topological insulators are typically expected to be associated with the formation of Landau levels or the Aharonov-Bohm effect. We instead study the conductance of Dirac surface states subjected to an in-plane magnetic field in the presence of a barrier potential. Strikingly, we find that, in the case of large barrier potentials, the surface states exhibit pronounced oscillations in the conductance when varying the magnetic field, in the absence of Landau levels or the Aharonov-Bohm effect. These novel magnetic oscillations are attributed to the emergence of super-resonant transport by tuning the magnetic field, in which many propagating modes cross the barrier with perfect transmission. In the case of small and moderate barrier potentials, we identify a positive magnetoconductance due to the increase of the Fermi surface by tilting the surface Dirac cone. Moreover, we show that for weak magnetic fields, the conductance displays a shifted sinusoidal dependence on the field direction with period π and phase shift determined by the tilting direction with respect to the field direction. Our predictions can be applied to various topological insulators, such as HgTe and Bi_{2}Se_{3}, and provide important insights into exploring and understanding exotic magnetotransport properties of topological surface states.

Gaussian optical networks for one-dimensional anyons

We study the dynamics of bosonic and fermionic anyons defined on a one-dimensional lattice, under the effect of Hamiltonians quadratic in creation and annihilation operators, also called Gaussian Hamiltonians. These anyonic models are obtained from deformations of the standard bosonic or fermionic commutation relations via the introduction of a nontrivial exchange phase between different lattice sites. We study the effects of the anyonic exchange phase on the usual bosonic and fermionic bunching behaviors. We show how to exploit the inherent Aharonov-Bohm effect exhibited by these particles to build a deterministic, entangling two-qubit gate and prove quantum computational universality in these systems. We define coherent states for bosonic anyons and study their behavior under two-mode passive, Gaussian devices. In particular we prove that, for a particular value of the exchange factor, an anyonic mirror can generate cat states, an important resource in quantum information processing with continuous variables.

Geometric phase for Dirac Hamiltonian under gravitational fields in the nonrelativistic regime

We show the appearance of geometric phase in a Dirac particle traversing in nonrelativistic limit in a time-independent gravitational field. This turns out to be similar to the one originally described as a geometric phase in magnetic fields. We explore the geometric phase in the Kerr and Schwarzschild geometries, which have significant astrophysical implications. Nevertheless, the work can be extended to any spacetime background including that of time-dependent. In the Kerr background, i.e. around a rotating black hole, geometric phase reveals both the Aharonov–Bohm effect and Pancharatnam–Berry phase. However, in a Schwarzschild geometry, i.e. around a nonrotating black hole, only the latter emerges. We expect that our assertions can be validated in both the strong gravity scenarios, like the spacetime around black holes, and weak gravity environment around Earth.

Element Decay

This paper attempts to establish the existence of element decay by making a historical case for the existence of theory decay, a phenomenon where theories leave an agent’s mosaic without any re-evaluation or decision on the agent’s part. The phenomenon of theory decay is to be theoretically distinguished from rejection without replacement; while the latter is a result of an agent’s deliberation, the former is a result of an agent’s inaction. To locate historical instances of theory decay, there should be evidence that the agent under study existed continuously throughout the period under study, that the theory was accepted at some point and unaccepted at some later point, and that the theory left the mosaic without any decision on the part of the agent. With these indicators at hand, I discuss five potentially promising historical cases: Poisson distribution, the Aharonov-Bohm effect, Damascus steel, Greek fire, and Cremonese violins. I argue that there is solid historical evidence to interpret the last case as an instance of element decay, which is sufficient to establish the existence of the phenomenon. I show that element decay is best seen as a non-scientonomic phenomenon; its existence highlights that individual and communal agents have limited capacities of knowledge retention and transmission and, when these limits are reached, element decay often takes place. This suggests that sufficient epistemic capacity to retain and transmit knowledge is a necessary precondition for the existence of scientonomic patterns, which emerge and hold only when the agent has measures in place to counteract potential element decay.