Gate voltage-dependent Aharanov–Bohm experiment in the presence of Rashba spin–orbit interaction

We measured gate voltage-dependent Aharonov–Bohm oscillations in an InGaAs-based two-dimensional electron gas ring with a gate on top of one of the branches. After ensemble averaging, the h/e oscillation spectrum showed smooth oscillatory behavior as a function of the gate voltage. This could be a manifestation of the spin–orbit interaction induced interference.     

Phase slips in Aharonov–Bohm oscillations

We give a possible mechanism for periodically occurring phaseslips in Aharonov–Bohm oscillations of mesoscopic rings.     

Aharonov–Bohm effect in Kane-type semiconductor quantum wire

In the present study, the Aharonov–Bohm effect for bound states in Kane-type quantum wire is analysed. It is demonstrated that the wave function and the energy spectra of carriers depend on the magnetic flux. The energy and the g factor of electrons are of a periodic function of the magnetic flux. The statistical property of the orbital magnetism of electrons at low temperatures and strong magnetic fields is presented. It is shown that the magnetisation of electron oscillations depends on the magnetic flux.     

Coherence properties of submicron GaAs/AlGaAs rings with a ferromagnetic gate

In the present work, the Aharonov–Bohm effect in submicron GaAs/AlGaAs ring with an in-plane ferromagnetic gate is investigated. The experiment is based on the study of the derivatives of magnetoresistance and microwave EMF to gate voltage. The experimental results are explained by electron wave interference in the presence of an inhomogeneous magnetic field in the ring.     

On the Aharonov–Bohm Hamiltonian

Using the theory of self-adjoint extensions, we construct all the possible Hamiltonians describing the nonrelativistic Aharonov–Bohm effect. In general, the resulting Hamiltonians are not rotationally invariant so that the angular momentum is not a constant of motion. Using an explicit formula for the resolvent, we describe the spectrum and compute the generalized eigenfunctions and the scattering amplitude.     

Coherent nonlinear transport in quantum rings

While equilibrium properties of mesoscopic systems are well understood, many questions are still debated concerning the non-equilibrium properties, which govern nonlinear transport. Nonlinear transport measurements have been performed on two-terminal semiconductor quantum rings in the open regime, where the rings are used as electron interferometers and show the Aharonov–Bohm effect. We observe a magnetic field asymmetry of the nonlinear conductance, compatible with the non-validity of the Onsager–Casimir relations out-of-equilibrium. In particular, the voltage-antisymmetric part of the nonlinear conductance of these two-terminal devices is not phase rigid, as it is the case for the linear conductance. We show that this asymmetry is directly related to the electronic phase accumulated by the electrons along the arms of the ring and can be tuned using an electrostatic gate.     

Quantum coherence in quantum dot—Aharonov–Bohm ring hybrid systems

We investigate coherent transport through hybrid systems of quantum dots and Aharonov–Bohm (AB) rings. Strong coherence over the entire system leads to the Fano effect, which originates from the interference and the phase shift caused by the discrete states in the dots. The high controllability of the system parameters reveals that the Fano effect in mesoscopic transport can be a powerful tool for detecting the phase shift of electrons. We apply it to detect electrostatic phase modulation and the phase shift in a quantum wire with a side-coupled dot. Finally, we provide an experimental answer to the problem of “neighboring in-phase Coulomb peaks”.     

Control of Aharonov–Bohm oscillations in a AlGaAs/GaAs ring by asymmetric and symmetric gate biasing

The control of the Aharonov–Bohm effect on a AlGaAs/GaAs ring structure is studied by employing two in-plane-gates. By applying a gate voltage to one of the gates, a change of the oscillation pattern due to the additional potential induced in one branch of the ring is observed. The change of the oscillation frequency as well as the phase is attributed to the multi-channel transport. In case of a symmetric biasing, where both gates are biased simultaneously, a larger voltage is required to change the oscillation pattern than for the case when only one gate is used. This effect is explained by a partial compensation of the phase difference between both branches of the ring.     

Quantum Information of the Aharanov–Bohm Ring with Yukawa Interaction in the Presence of Disclination

We investigate quantum information by a theoretical measurement approach of an Aharanov–Bohm (AB) ring with Yukawa interaction in curved space with disclination. We obtained the so-called Shannon entropy through the eigenfunctions of the system. The quantum states considered come from Schrödinger theory with the AB field in the background of curved space. With this entropy, we can explore the quantum information at the position space and reciprocal space. Furthermore, we discussed how the magnetic field, the AB flux, and the topological defect influence the quantum states and the information entropy.     

Aharonov–Bohm oscillations observed in nanoscale open-dot structures fabricated in an InAs surface inversion layer

We fabricated nanoscale open-dot structures in an InAs surface inversion layer using an atomic-force-microscope oxidation process. Due to its superior nanofabrication capability, small open-dot structures with the feature size ranging between 100 and 300 nm were successfully fabricated. The magnetoresistance signal measured at 4.2 K showed reproducible fluctuations and a periodic oscillation component that varies in both amplitude and periodicity depending on the dot size. We show that the period of the oscillations corresponds to that of the Aharonov–Bohm effect and propose that the possible mechanism for the oscillations is due to the formation of a one-dimensional electron channel enclosing the open-dot structure as a result of the electron transfer from the InAs oxide to InAs.     

Angular magnetoresistance oscillations in bilayers in tilted magnetic fields

Angular magnetoresistance oscillations (AMRO) were originally discovered in organic conductors and then found in many other layered metals. It should be possible to observe AMRO to semiconducting bilayers as well. Here we present an intuitive geometrical interpretation of AMRO as the Aharonov–Bohm interference effect, both in real and momentum spaces, for balanced and imbalanced bilayers. Applications to the experiments with bilayers in tilted magnetic fields in the metallic state are discussed. We speculate that AMRO may be also observed when each layer of the bilayer is in the composite-fermion state.     

Impurity effects in the optical absorption of quantum rings

We study the interplay between impurity scattering and Coulomb interaction effects in the absorption spectrum of neutral bound magnetoexcitons confined in quantum-ring structures. Impurity scattering breaks the rotational symmetry of the ring system, introducing characteristic features in the optical emission. Signatures of the optical Aharonov–Bohm effect are still present for weak scattering and strong Coulomb screening. Furthermore, an impurity-induced modulation of the absorption strength is present even for a strong impurity potential and low screening. This behavior is likely responsible of recent experimental observations in quantum-ring structures.     

Magneto-optical spectroscopy of carbon nanotubes

We review our recent optical experiments on single-walled carbon nanotubes in high magnetic fields. The data revealed magnetic-field-induced optical anisotropy as well as broadening, splittings, and shifts of interband absorption and photoluminescence peaks. Quantitative comparison with theoretical predictions based on the Aharonov–Bohm effect is presented.     

Investigation of the mesoscopic Aharonov–Bohm effect in low magnetic fields

We have investigated the Aharonov–Bohm effect in mesoscopic semiconductor GaAs/GaA1As rings in low magnetic fields. The oscillatory magnetoconductance of these systems is systematically studied as a function of electron density. We observe phase shifts of π in the magnetoconductance oscillations, and halving of the fundamental h/e period, as the density is varied. Theoretically, we find agreement with the experiment, by introducing an asymmetry between the two arms of the ring.     

Interference and interactions in mesoscopic rings

We consider a mesoscopic ring connected to external reservoirs by tunnel junctions. The ring is capacitively coupled to an external gate electrode and may be pierced by a magnetic field. Due to strong electron–electron interactions within the ring the conductance shows Coulomb blockade oscillations as a function of the gate voltage, while Aharonov–Bohm interference effects lead to a dependence on the magnetic flux. The Hamiltonian of the ring is given by a Luttinger model that allows for an exact treatment of both interaction and interference effects. We conclude that the positions of conductance maxima as a function the external parameters can be used to determine the interaction parameter , and the shapes of conductance peaks are strongly affected by electron correlations within the ring.     

To Believe Or Not Believe In The A Potential, That’s a Question. Flux Quantization in Autistic Magnets. Prediction of a New Effect

Electromagnetic gauge as an integration condition was my wording in previous publications. I argue here, on the examples of the Möllenstaedt-Bayh and Tonomura tests of the Ahraronov–Bohm (AB) effect, that not only the trapped flux but also, under the integration condition A 0 if = 0, the local value of the vector potential is measured.     

Dimension in a Radiative Stellar Atmosphere

Dimensional scales are examined in an extended 3 + 1 Vaidya atmosphere surrounding a Schwarzschild source. At one scale, the Vaidya null fluid vanishes and the spacetime contains only a single spherical 2-surface. Both of these behaviors can be addressed by including higher dimensions in the spacetime metric.     

Period doubling effects in the oscillations of persistent currents in discretized Aharonov–Bohm rings

One shows that the oscillations with respect to the magnetic flux in the one-dimensional discretized Aharonov–Bohm rings are sensitive with respect to the parity of the number of electrons N_e. Resorting to basic flux intervals of unit length indicates that the period of such oscillations is given by the flux quantum Φ₀=hc/e and by 2Φ₀ if N_e is odd and even, respectively. Accordingly, one deals with a period doubling effect when passing from odd N_e-values to even ones, which may be useful in the design of further nanodevices. Interaction free limits of the Drude weight are also discussed.