The Forked Blazed Grating as a Quasioptical Element for Gyrotron Applications

In previous papers we have shown how beams of millimeter-wavelength electromagnetic radiation with phase singularities can be generated by diffraction from a specially-configured forked blazed grating. Here we consider how the hollow conical beam output of a gyrotron is diffracted by this kind of grating. Two applications are considered; using the grating (a) as a single-element quasioptical antenna to convert the output into a well-collimated gaussian-like beam and (b) as a device to enable the estimation of the fractions in oppositely-rotating modes in the gyrotron output.     

A millimeter-wave geometric phase interferometer

A millimeter-wave interferometer operating purely on the geometric phase is presented. Like its optical counterpart described by Hariharan and Roy, this system uses two circular polarizers with a half-wave section in between. The geometric phase of each signal is determined by the orientation of the half-wave section.     

Comparison of Volume and Integrated P-I-N Modulators in Millimeter Wave Range

Volume and based on surface oriented integrated p-i-n-structures modulators have demonstrated high efficiency in millimeter wave range as quasi-optical modulators and phase shifters. These structures possess high modulation and high-speed properties; sustain great EM powers. However, the modulation characteristics of p-i-n modulators of both mentioned types in millimeter wave range have not been investigated yet. Here, a comparison and criteria of volume and integrated based on Si surface oriented structure modulators in millimeter wave range are presented.     

Geometric Phase of a Coupled System

In this contribution, my main attention is paid to the study of the geometric phase ora two-level system.Asymptotic expansion of the eigenvalue and analytic information are obtained. The results are illustrated with an application to a specific atomic system.     

The Millimeter Wave Tomography Application for the Subsurface Imaging

In the present paper new results of modeling and experimental investigation on millimeter wave subsurface tomography are submitted. Tomographic algorithm is employed for imaging of subsurface objects in the case when conductivity of probed medium is not equal to zero. The possibilities and restrictions of this algorithm for image processing are shown both as a result of modeling and as a result of experiments. A new tomography setup allowing obtaining images of different inhomogeneities in dielectric media is considered.     

Geometric Phase of a Coupled System

In this contribution, my main attention is paid to the study of the geometric phase of a two-level system.Asymptotic expansion of the eigenvalue and analytic information are obtained. The results are illustrated with an application to a specific atomic system.     

Dynamic and Geometric Phase Formulas in the Hestenes-Dirac Theory

We examine the dynamic and geometric phases of the electron in quantum mechanics using Hestenes' spacetime algebra formalism. First the standard dynamic phase formula is translated into the spacetime algebra. We then define new formulas for the dynamic and geometric phases that can be used in Hestenes' formalism.     

Geometric Phase and Bose-Einstein Condensate

We show that a geometric phase may appear in the Bose-Einstein condensate (BEC) in which an adiabatic procedure happens, then a perturbation expression of geometric phase is obtained for the case of time-averaged orbiting potential trap. The phase caused by the adiabatic bias magnetic field in one BEC may interfere with another, which is similar to the phase interference of Aharonov-Susskind effect, and can be observed by experiments.     

Geometric Phase in a Time-Dependent A-Type Jaynes-Cummings Model

By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical and the geometric phases in a generalized time-dependent A-type Jaynes Cummings model. We lind that, compared with the dynamical phases, the geometric phases in a cycle case are independent of the frequency of the photon field, the coupling coefficient between photons and atoms, and the atom transition frequency. It is pointed out that the geometric phases in a cycle ease can be measured under the case of a stronger time-dependent photon field and a stronger coupling photon-atom system. On the other hand, the geometric phases of the model may be measured in the composition of cold atoms.     

关于Berry几何位相理论的推广

对于可参数化时间t的周期Hamiltonian系统,由non－adiabatic到adiabatic－limit的“严格”演变以获得Berry几何相γn（C）的问题．结果表明,存在“四种类型”的演变态,它们都可以满足在参数R空间中的同一条闭合曲线C上作这样的“严格演变”,并且还都可以获得同一个Berry几何相γn（C）;而Berry发现这一几何相γn（C）时所考虑和采用的“演变态”,恰好属于本文“四种类型”的“严格”演变态之一的adiabaticapproximation情形．据此,可以把Berry几何位相理论推广到本文所研究的“四种类型”的“严格”演变中．     

Nondestructive Material Homogeneity Characterization by Millimeter Waves

Millimeter wave bridge technique for nondestructive material homogeneity characterization is described. The idea of this technique is the local excitation of millimeter waves in testing material and the measurement of the transmitted amplitude and phase in it different places. Some results of the homogeneity measurements for the dielectric substrates are presented.     

Demonstration of the Holonomically Controlled Non-Abelian Geometric Phase in a Three-Qubit System of a Nitrogen Vacancy Center

The holonomic approach to controlling (nitrogen-vacancy) NV-center qubits provides an elegant way of theoretically devising universal quantum gates that operate on qubits via calculable microwave pulses. There is, however, a lack of simulated results from the theory of holonomic control of quantum registers with more than two qubits describing the transition between the dark states. Considering this, we have been experimenting with the IBM Quantum Experience technology to determine the capabilities of simulating holonomic control of NV-centers for three qubits describing an eight-level system that produces a non-Abelian geometric phase. The tunability of the geometric phase via the detuning frequency is demonstrated through the high fidelity (~85%) of three-qubit off-resonant holonomic gates over the on-resonant ones. The transition between the dark states shows the alignment of the gate’s dark state with the qubit’s initial state hence decoherence of the multi-qubit system is well-controlled through a π/3 rotation.     

Rain Attenuation at Millimeter Wavelengths

A method of determining the rationality for raindrop size distribution is first presented. The relative volume occupied by raindrops is derived. The attenuation and cross-polar discrimination induced by rainfall at millimeter waves are investigated with the incoming expression and a brief analysis is presented.     

Geometric Phase Observation with Dispersed Fringes

Geometric and dynamic phases are separately observed using dispersed fringes, and the difference between them is clearly demonstrated. Independence of geometric phase of wavelength is straightforwardly shown in the dispersed fringe.     

Influence of Bipartite Qubit Coupling on Geometric Phase

The geometric phase of the bipartite Heisenberg spin-1/2 system with one spin driven by rotating magnetic field is investigated. It is found that in the one-site drive case, the intersubsystem coupling can be equivalent to a static quasi-magnetic field in the parameter space. This perspective has satisfactorily explained the irregular asymptote effect of geometric phase. We discuss the property of the two-site magnetic drive spin system and discover that a stationary state with no geometric phase shift is generated.     

Influence of Bipartite Qubit Coupling on Geometric Phase

The geometric phase of the bipartite Heisenberg spin-1/2 system with one spin driven by rotating magnetic field is investigated. It is found that in the one-site drive case, the intersubsystem coupling can be equivalent to a static quasi-magnetic field in the parameter space. This perspective has satisfactorily explained the irregular asymptote effect of geometric phase. We discuss the property of the two-site magnetic drive spin system and discover that a stationary state with no geometric phase shift is generated.     

Implementation of Controlled Geometric Phase Gate for Two Trapped Neutral Atoms

We propose a scheme for realizing a controlled geometric phase gate for twoneutral atoms. We apply the stimulated Raman adiabatic passage to transferatoms from their ground states into Rydberg excited states, and use theRydberg interaction induced energy shifts to generate geometric phase andconstruct quantum gates.     

Geometric Phase Based Circular Array for Multimode Vortex Beam Generation

A geometric phase model for electromagnetic radiating elements is proposed. By rotation of the radiating element, a frequency‐independent geometric phase occurs for circularly polarized components of radiation field along every direction in far field. In addition, the geometric phase is equal to the rotation angle for a circularly polarized source, which enables phase modulation ranging from 0 to 2π. In contrast, the Pancharatnam–Berry phase for circular polarization conversion components brought by optical element rotation is twice the rotation angle and is applicable only for the scattering waves propagating along the rotation axis. As a proof of principle, an antenna array is designed and fabricated in microwave regime to verify the phase modulation approach. Both the calculated and measured results verify that three different orbital angular momentum modes are generated simultaneously at 8.5 GHz and 11.5 GHz.     

Millimeter Wave Band Cavity Resonators for Magnetoresonance Experiments

Electrodynamical features of rectangular cavity resonators as experimental cells of Electron Spin Resonance spectrometer for the millimeter frequency band have been investigated. Measurements and analytical estimations of features of three types of resonators (film-wall type, diffraction grating-wall type, double-wall type) are presented. The advantages and imperfections of each design as well as recommendations for their applications in millimeter wave magnetospectroscopy are given.     

Millimeter wave propagation in transmission lines with magnetized semiconductor element

The peculiarities of electromagnetic wave propagation in transmission lines with a gyromagnetic semiconductor element are analysed. Electromagnetic radiation control is shown to be possible when semiconductor element contacts with the waveguide from the outside and constitutes a part of the transmission line itself. The afore-named possibility is demonstrated using rectangular metal and dielectric waveguides as well as a microstrip line.