P, T violating magneto-electro-optics

We study linear and bilinear magneto-electro-optical effects due to the propagation of light in centro-symmetric media in the presence of P, T violating interactions and external transverse and longitudinal electric and/or magnetic fields. We show that new magneto-electric optical effects appear. In particular, we show the existence of a Jones birefringence proportional to the square of the transverse field amplitude. All these effects are an unambiguous signature of the P, T violation, and a search for such new phenomena could also provide novel limits on electric dipole moment (EDM) of matter.     

Holonomic quantum computation based on the scalar Aharonov–Bohm effect for neutral particles and linear topological defects

We discuss holonomic quantum computation based on the scalar Aharonov–Bohm effect for a neutral particle. We show that the interaction between the magnetic dipole moment and external fields yields a non-abelian quantum phase allowing us to make any arbitrary rotation on a one-qubit. Moreover, we show that the interaction between the magnetic dipole moment and a magnetic field in the presence of a topological defect yields an analogue effect of the scalar Aharonov–Bohm effect for a neutral particle, and a new way of building one-qubit quantum gates.     

Radiation of the Point Source from an Anisotropic Plasma Cylinder

We obtain and analyze an analytical solution to the problem of electromagnetic-wave radiation of the point electric dipole from an anisotropic plasma cylinder to free space. Two cases of the dipole orientation are considered, where the electric dipole is directed along and across a horizontal magnetic field whose direction does not coincide with the axes of a cylindrical coordinate system. We analyze how the conditions and characteristics of the resonance influence of the anisotropic plasma cylinder depend on the strength of the magnetic field and its direction with respect to the dipole moment of the source. Comparative analysis of the resonance influence of the plasma cylinder with horizontal and axial external magnetic fields is performed.     

Low-frequency complex magnetic susceptibility of magnetic composite microspheres in colloidal dispersion

A procedure is presented to determine the permanent magnetic dipole moment of composite microspheres containing magnetic nanoparticles with a blocked magnetic dipole moment. The composite particles are dispersed in a solvent, and the complex magnetic susceptibility is measured from 0.1 to 1000 Hz using a highly sensitive new setup. Composite particles with a permanent magnetic dipole moment are revealed by a characteristic frequency that corresponds to the Brownian rotation of the microspheres. From measured susceptibility spectra, we calculate the permanent magnetic dipole moment of recently developed cobalt ferrite-doped silica and latex microspheres.     

First-principles studies of the magnetic hyperfine field in Fe multilayers

A detailed theoretical study of the magnetic moments and magnetic hyperfine fields in several Fe multilayers (Fe fcc(001)/5X fcc(001), X=Cu and Ag, and Fe bcc(001)/5X fcc(001), X=Ag and Au) as well as in bulk Fe is presented. The calculations have been performed using the spin-polarized, relativistic linear muffin-tin orbital (SPR-LMTO) method of band structure calculation. Therefore, not only the contribution to the hyperfine fields due to the conventional Fermi contact interaction but also due to the spin dipolar and orbital contributions induced by the crystal field and by spin-orbit coupling are accounted for. To decompose the hyperfine field of non-s-electrons into these contributions it has been assumed that they are proportional to the corresponding so-called magnetic dipole moment and the orbital magnetic moment, respectively. In contrast to previous results for pure metals and alloys not only the orbital but also the spin dipolar hyperfine field was found to be non-negligible. The anisotropy of the hyperfine field determined by calculations for in-plane and perpendicular orientation of the magnetisation was found to be very pronounced and closely connected with the corresponding anisotropy of the magnetic dipole moment and the orbital moment.     

Polar nano-rods under shear: From equilibrium to chaos

The orientational dynamics of rod-like particles with permanent (electric or magnetic) dipole moments in a plane Couette shear flow is investigated using mesoscopic relaxation equations combined with a generalized Landau free energy. The free energy contribution due to the coupling between average alignment and dipole orientation is derived on a microscopic basis. Numerical results of the resulting eight-dimensional dynamical system are presented for the case of longitudinal dipoles and thermodynamic conditions where the equilibrium state is a (polar or non-polar) nematic. Solution diagrams reveal presence of a large variety of periodic, transient chaotic, and chaotic dynamic states of the average alignment and dipole moment, respectively, appearing as a function of Deborah number and tumbling parameter. Compared to rods without dipoles we observe a significant preference of out-of-plane kayaking-tumbling states and, generally, a higher sensitivity to the initial conditions including bistability. We also demonstrate that the average (electric) dipole moment characterizing most of the observed states yields electrodynamic (magnetic) fields of measurable strength.     

Towards a test of string theory using Rydberg atoms

The current controversy over the need for an experimental test of String Theory is considered. We report recent experiments on quasi-bound electrons in crossed electric and magnetic fields, in which states of very large electric dipole moment are excited. The excited electron is confined to one side of the atomic nucleus in the outer well of a controllable double-well potential. These states are discussed in relation to a recent theoretical proposal to test the spatial non-commutativity underpinning String Theory by studying Penning orbits of Rydberg atoms in crossed electric and magnetic fields.     

Electromagnetic field perturbation by an internal void in a conducting cylinder excited by a wire loop

A thin prolate spheroidal void in an infinite conducting circular cylinder is used to model an internal flaw in a wire rope. The rope is excited by an electric ring current which is a model for a thin solenoid or multi-turn wire loop. The anomalous external fields are computed from the induced electric and magnetic dipole moments of the void. For this type of excitation, the induced axial magnetic dipole moment is the dominant contributor to the scattered field. The results have application to nondestructive testing of wire ropes.     

A multi-energy-level lattice Boltzmann model for Maxwell’s equations without sources

A lattice Boltzmann model for the Maxwell’s equations without sources is proposed by taking separate sets of distribution functions for the electric and magnetic fields and using the higher-order moment method. The higher-order moment method is based on the solution of a series of partial differential equations obtained by multi-energy-level techniques, multi-scale techniques, and Chapman–Enskog expansion, As numerical examples, some classical electromagnetic phenomena, such as the electric field and equipotential lines around an electrostatic dipole, the electric and magnetic fields around oscillating dipoles are given. These numerical results agree well with classical ones.     

Origin and scaling of the permanent dipole moment in CdSe nanorods

Transient electric birefringence measurements were performed on dilute solutions of CdSe nanorods. The results confirm the existence of a permanent dipole along the c-crystallographic axis. Measurements on nanorods with different widths and lengths show that the longitudinal permanent dipole moment scales linearly with volume, suggesting it arise from the noncentrosymmetric crystallographic lattice.     

Radiative corrections to the Lagrangian of the electromagnetic field

The single-loop corrections to the Lagrangian of a uniform, constant electromagnetic field are found which include the anomalous magnetic moment and electric dipole moment of the electron. The imaginary part of the effective Lagrangian, which determines the probability of electron-positron pair production is found. The asymptotic behavior of the effective action is studied for supercritical magnetic fields H » H₀ = m²/e with the dependence of the anomalous magnetic moment on H taken into account.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 37–42, March, 1987.     

Magnetic birefringence of iron oxyhydroxide nanoparticles stabilised by sucrose

Magnetically induced optical birefringence is used to investigate pharmaceutically important iron-sucrose aqueous suspensions. XRD and TEM measurements of the system of oxyhydroxide particles stabilised by sucrose have shown that this system contains iron oxyhydroxide in the form of 2-5 nm particles. The mineral form of the iron-core is suggested to be akaganeite. Anisotropy of the optical polarizability and magnetic susceptibility of akaganeite nanoparticles are calculated. The permanent dipole moment obtained for the nanoparticles studied was found to be negligible, in agreement with the characteristic superparamagnetic behaviour of the magnetic nanoparticles observed at room temperature. The Neel temperature of these nanoparticles is estimated as below 276 K. The results obtained are discussed against a background of the earlier studies of similar nanoscale systems.     

Wigner Rotations and Precession of Polarization

An easy and direct derivation of Thomas precession is obtained from infinitesimal Wigner rotations arising in unitary representations of the Poincaré group. For spin > 1/2, multipole parameters are studied from this point of view. The canonical 3-component definition of polarization arising naturally in this context is compared with formalisms which start form a pseudo 4-vector and an antisymmetric tensor respectively. The full Thomas equations, including Larmor precession, is derived using time derivatives of finite Wigner rotations. Exact solutions, with arbitrary initial conditions, are presented for constant magnetic fields and for orthogonal constant electric and magnetic fields. For a class of plane wave external fields exact solutions are obtained for the Dirac equation generalized by the inclusion of anomalous magnetic moment (Pauli) and electric dipole moment terms. Using the front form of dynamics, well-adapted to this context and coinciding with proper time dynamics, expectation values are calculated. The polarization pseudo 4-vector thus obtained is shown to satisfy the BMT equation, which is equivalent to the Thomas equation. This shows that the validity of the classical precession equations is not necessarily restricted to slowly varying external fields. These solutions can also be of interest in the study of spin 1/2 particles in laser fields and in the study of electric dipole moments.     

微波驱动精细结构能级跃迁引起的电磁诱导负折射效应

本文通过建立Λ形四能级原子系统, 研究了微波驱动精细结构能级跃迁引起的电磁诱导负折射效应. 微波场作用于基态精细结构能级之间, 与不同精细结构能级之间的电偶极矩或磁偶极矩发生耦合, 使系统在某些频率处呈现负折射特性.同时, 两个耦合场各自激励一对基态和激发态之间的光学跃迁. 通过改变两个耦合场的频率失谐量控制负折射区域的频带宽度.结果表明, 耦合场失谐时出现负折射特性的频率范围比耦合场共振时迅速缩小, 而且耦合场负失谐和正失谐时的变化规律不同.     

Magnetic force signal of vortex creation in type-II superconducting thin films

The possibility of the formation of a vortex in thin film due to the field of magnetic dipole moment when a point dipole is vertically approaching the surface of a thin film is discussed. Calculations are performed for certain discrete values of the critical position of the point dipole for creating the vortex in the thin film and the equilibrium positions of the vortex, both of which depend on the strength of magnetic dipole moment. The creation of a new single vortex in the thin film causes an abrupt change in the vertical force.     

Effect of the neutrino magnetic moment on the properties of the muon

The effect of the neutrino dipole magnetic moment on the properties of the muon is investigated within the standard model of electroweak interactions and a model based on the SU(2) _L × SU(2) _R × U(1) _B-L gauge group (left-right model). In the case of the Dirac neutrino, muon decay through the channel µ^? → e ^?γ is studied with allowance for the neutrino dipole magnetic moment. It is shown that, both in the standard model supplemented with an SU(2) _L right-handed neutrino singlet and in the standard model featuring two doublets of Higgs fields, radiative muon decay is unobservable. In the left-right model, the contributions of diagrams associated with the neutrino dipole magnetic moment become significant only in the case of a mutual compensation of the contributions of diagrams involving the electromagnetic vertices of charged gauge bosons and singly charged Higgs bosons. At specific values of the parameters of the left-right model, one can then obtain an experimental upper limit on the branching fraction of this reaction. The contributions of the neutrino dipole magnetic moment to the muon anomalous magnetic moment are found for the Dirac and the Majorana neutrino. It is established that, both in the standard model and in the left-right model, values of the neutrino anomalous magnetic moment that are required for explaining the (g ? 2)_µ anomaly are in excess of the theoretical predictions for this moment.     

Time-reversal-violating generation of static magnetic and electric fields and a problem of electric dipole moment measurement

It is shown that in the experiments for the search of the electric dipole moment of an electron (atom, molecule) the T-odd magnetic moment induced by an electric field and the T-odd electric dipole moment induced by a magnetic field will be also measured. How to distinguish these contributions is discussed here.     

The deuteron and its magnetic moment the effects of non-local nuclear forces and of unitary transformations

The deuteron theory is renewed and completed for non-local Hamiltonians. A method to calculate deuteron wave functions is given. The formula for the current density and the magnetic dipole moment of a non-local potential is derived, and applied to the GCT, GT, and HJ-potential. The effects of a unitary transformation on the deuteron data — electric quadrupole moment, magnetic dipole moment, and radius — are shown. For the numerical calculations the Ristig-Kistler transformation and the HJ-potential were used. It is shown that an overall fit cannot be reached.     

Extraction of hyperfine anomalies without precise values of the nuclear magnetic dipole moment

A new method for extracting the hyperfine anomaly from experimental hyperfine structure constants is suggested. Instead of independent high-precision measurements of the nuclear magnetic dipole moment, precise measurements of magnetic dipole hyperfine interaction constants for two atomic states and a theoretical analysis can be used. This can lead to determination of hyperfine anomaly for radioactive isotopes where the nuclear magnetic dipole moment is not known with high accuracy. Received: 17 February 1998