Nonconserving Transition Research Articles

Spin and charge localisation due to the interplay of Ac gate voltage and spin–orbit interaction

ABSTRACT We investigate the effects of a time-dependent gate voltage on a spin–orbit interaction (SOI) coupled interacting double quantum dot (DQD) system. For a tunnel coupled detuned DQD with two interacting electrons, SOI couples triplet and hybridised singlet state (1,1)–(0,2) through spin nonconserving transition. In order to explore the effects of Ac gate voltage on charge localisation, we initiate the system in the vicinity of the singlet–triplet avoided crossing and investigate the interplay of the Ac gate voltage and SOI on the charge and spin dynamics of the system. We show that the triplet state (1,1) charge configuration can be frozen by tuning the Ac frequency leading to charge localisation and dynamical spin locking with a redefined spin–orbit field in terms of gate voltage.

Optimal boundary control of a nonstandard viscous Cahn–Hilliard system with dynamic boundary condition

In this paper, we study an optimal boundary control problem for a model for phase separation that was introduced by Podio-Guidugli (2006). The model consists of a strongly coupled system of nonlinear parabolic differential equations, in which products between the unknown functions and their time derivatives occur that are difficult to handle analytically. In contrast to the existing control literature about this PDE system, we consider here a dynamic boundary condition involving the Laplace–Beltrami operator for the order parameter of the system, which models an additional nonconserving phase transition occurring on the surface of the domain. We show the Fréchet differentiability of the associated control-to-state operator in appropriate Banach spaces and derive results on the existence of optimal controls and on first-order necessary optimality conditions in terms of a variational inequality and the adjoint state system.

Global Existence for a Nonstandard Viscous Cahn--Hilliard System with Dynamic Boundary Condition

In this paper, we study a model for phase segregation taking place in a spatial domain that was introduced by Podio-Guidugli [Ric. Mat., 55 (2006), pp. 105--118]. The model consists of a strongly coupled system of nonlinear parabolic differential equations, in which products between the unknown functions and their time derivatives occur, that are difficult to handle analytically. In contrast to the existing literature about this PDE system, we consider here a dynamic boundary condition involving the Laplace--Beltrami operator for the order parameter. This boundary condition models an additional nonconserving phase transition occurring on the surface of the domain. Different well-posedness results are shown, depending on the smoothness properties of the involved bulk and surface free energies.

Intramolecular radiationless transition or background cosmic field effect in NO2

Optical excitation induces a transition in NO2 from a ground state |a> to an excited state |b>. The state |b> is not stable. The molecule evolves irreversibly from |b> to a state |c> in a time τ0≈3μs. We investigate the transition from |b> to |c> by analysing results of molecular beam and static gas experiments, and we conclude that the irreversible evolution is either an intramolecular radiationless transition of a symmetric to an asymmetric configuration of the isolated NO2 or the effect of a background cosmic field inducing a parity nonconserving transition from |b> to |c>.

Erratum: Relations between matrix elements of different weak interactions and interpretation of the parity-nonconserving and electron electric-dipole-moment measurements in atoms and molecules [Phys. Rev. A84, 052108 (2011)

The relations between matrix elements of different P- and T-odd weak interactions are derived. We demonstrate that similar relations hold for parity nonconserving (PNC) transition amplitudes and electron electric dipole moments (EDM) of atoms and molecules. This allows to express P- and T-odd effects in many-electron systems caused by different symmetry-breaking mechanisms via each other using simple analytical formulas. We use these relations for the interpretation of the anapole moment measurements in cesium and thallium and for the analysis of the relative contributions of the scalar-pseudoscalar CP-odd weak interaction and electron EDM to the EDM of Cs, Tl, Fr and other atoms and many polar molecules (YbF, PbO, ThO, etc.). Model-independent limits on electron EDM and the parameter of the scalar-pseudoscalar CP-odd interaction are found from the analysis of the EDM measurements for Tl and YbF.

Vacuum-Polarization Corrections to Parity-Nonconserving Effects in Atomic Systems

The dominant one-loop vacuum-polarization correction to atomic wave functions are evaluated for the 6s–7s parity nonconserving (PNC) E1 transition amplitude in cesium. This correction increases the size of the PNC amplitude by 0.4% and thus increases the difference between the experimental value of the weak charge Q W and the one predicted by the standard model.

High-precision calculation of parity nonconservation in cesium and test of the standard model

We have calculated the 6s-7s parity nonconserving (PNC) E1 transition amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in the calculation of the correlations and have included all significant contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times 10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations used for the interpretation of Cs PNC experiments. The resulting nuclear weak charge Q_{W} for Cs deviates by about 2 standard deviations from the value predicted by the standard model.

Formula omitted]-nonconserving transition in heavily doped LPE grown n-type In 0.5Ga 0.5P

Heavily unintentionally doped n-type InGaP was grown by LPE technique. Temperature and excitation power dependence of PL measurements were carried out to investigate the first observed 2.107 eV PL peak in In 0.5Ga 0.5P and we confirmed the first k -nonconserving optical transition in In 0.5Ga 0.5P. Also the unintentionally doped major impurity was found to be sulfur through XRF technique.

A semi-empirical evaluation of parity non-conserving E1 transitions in thallium

The authors apply their previously-developed semi-empirical potential method in the calculation of the dominant high order many-body correlation effects in thallium which can be modelled by a central potential. The authors use this method to evaluate the thallium parity non-conserving electric dipole 6p1/2 to 7p1/2 and the 6p1/2 to 6p3/2 transitions. To estimate the accuracy of the calculation the authors also calculate the parity conserving E1 transition matrix elements and the hyperfine interaction constants. For the 6p1/2 to 7p1/2 parity non-conserving transition the authors obtain -7.97*10-11 (1+or-0.07) (-iea0QW/N) and for the 6p1/2 to 6p3/2 parity non-conserving transition -31.6*10-11 (1+or-0.09) (-iea0QW/N).

A semi-empirical ratio method for the calculation of parity non-conservation in caesium

The semi-empirical method proposed by Bouchiat et al (1986) for the calculation of the parity non-conserving E1 transition matrix element for the 6s1/2 to 7s1/2 transition in caesium is re-examined in terms of many body perturbation theory. A slightly modified formulation is derived and this is used to provide an improved value for the E1 amplitude. The value is E1PNC=0.904 (1+or-0.02)*10-11 (-iea0QW/N).

A semi-empirical approach to the calculation of parity non-conserving E1 transition matrix elements in caesium

In this paper the authors describe a semi-empirical, approach for calculating certain high-order perturbation effects in a simple manner. They use these modified orbitals in RPA type equations to give values for E1 transition matrix elements and hyperfine dipole constants that agree well with experiment. Including the spin-independent weak interaction leads to parity non-conserving equations. For the caesium 6s12/ to 7s1/2 parity non-conserving E1 transition they obtain 0.904(1+or-0.02)*10-11 (-iea0Qw/N).

Parity Non-Conservation and Pair Correlation in Heavy Atomic Systems

The increased accuracy of the experiments studying parity non-conserving effects in atoms calls for improvement also in the atomic calculations which are necessary to connect the experimental results to fundamental parameters. We show how the method of iterative solution of the two-dimensional "pair equation" can be used to treat the effect of pair correlation to all orders, also in the calculations of parity non-conserving transition elements.

PNC Equations of Motion method

We describe the application of the Equations of Motion method to the calculation of parity non-conserving (PNC) transition matrix elements in heavy atoms. We extend the usual formalism to include the PNC weak electron nucleus interaction and give results for a transition of experimental interest in Pb.

Measurement of the CP-nonconservation parameter epsilon '/ epsilon.

The value of $\frac{{\ensuremath{\epsilon}}^{\ensuremath{'}}}{\ensuremath{\epsilon}}$, a measure of the $\mathrm{CP}$-nonconserving direct transition from the ${K}_{L}^{0}$ state to the isospin-2 state of two pions, was determined to be 0.0017\ifmmode\pm\else\textpm\fi{}0.0082, a result that excludes interesting models of $\mathrm{CP}$ nonconservation.

Relativistic many-body perturbation theory of parity non-conservation in heavy atoms

The effect of residual many-electron interactions on the parity non-conservation in heavy atoms due to the nuclear spin-independent part of the weak neutral current interaction is calculated. The special feature of the method is the inclusion of the parity non-conserving term in the zeroth-order single-particle Hamiltonian. The basic single-particle states are eigenstates of angular momentum but not parity. Standard many-body perturbation methods are used to derive diagrammatic expressions for the resulting parity non-conserving E1 transition matrix elements. Some simplifying theorems are proved and the method for evaluating the zeroth- and first-order diagrams is outlined.