Mass Shift Of Electron Research Articles

Piezojunction effect in heterojunctions under external bias for ultrasensitive strain sensing

This paper investigates for the first time the piezojunction effect in heterojunctions under external bias for ultrasensitive strain sensing. As a proof of concept, we used sensing devices made of 3C-SiC/Si heterostructure with vertically aligned electrodes. Applying the beam bending method to characterize the sensing effect, the bending strain was introduced along the typical orientation [100] or [110] on (100) Si plane. Experimental results show a linear relationship between the relative change in the forward current and the applied strain from 0 to 500 ppm, decreasing under the tensile strain while increasing under the compressive strain. At the forward bias of 8 V, the obtained gauge factors (GFs) are 199.7 for [100] orientation and 173.1 for [110] orientation, which significantly enhance about 630 % and 540 % compared to the highest GF of n-type 3C-SiC in the literature. Interestingly, the GFs of the n+-3C-SiC/p-Si heterostructure are positive in contrast to the negative GFs of n-3C-SiC thin films. The results were explained by the strain modulation on the band split and electron mass shift along the out-of-plane direction as well as by the change in the barrier height, depletion region width, and carrier concentrations under the forward bias. The ultrasensitive piezojunction effect in the 3C-SiC/Si heterojunction demonstrated in this study can pave the way toward developing ultrasensitive mechanical sensors.

Electron mass shift in an intense plane wave

Upcoming experiments on the interaction of electrons with intense laser fields are envisaged to become more and more accurate, which calls for theoretical computations of rates and probabilities with correspondingly higher precision. In strong-field QED this requires the knowledge of radiative corrections to be added to leading-order results. Here, we first derive the mass operator in momentum space of an off-shell electron in the presence of an arbitrary plane wave. By taking the average of the mass operator in momentum space over an on-shell electron state, we obtain a new representation, equivalent to but more compact than the known one computed in [Sov. Phys. JETP \textbf{42}, 400 (1975)]. Moreover, we use the obtained mass operator to determine the electron mass shift in an arbitrary plane wave, which generalizes the already known expression in a constant crossed field. The spin-dependent part of the electron mass shift can be related to the anomalous magnetic moment of the electron in the plane wave. We show that within the locally constant field approximation it is possible to conveniently define a local expression of the electron anomalous magnetic moment, which reduces to the known expression in a constant crossed field. Beyond the locally constant field approximation, however, the interaction between the electron and the plane wave is non-local such that it is not possible to conveniently introduce an electron anomalous magnetic moment.

On the Usage of Tapered Undulators in the Measurement of Interference in the Intensity-Dependent Electron Mass Shift

In nonlinear Thomson scattering, the main emission line and its harmonics form a band-like structure due to the laser pulse shape induced ponderomotive broadening. We propose to use tapered undulators to mimic Thomson scattering and measure the intensity-dependent electron mass shift experimentally. We also numerically show that the effect is observable for realistic electron beams like in DESY or SKIF.

Intensity-Dependent Electron Mass Shift in a Laser Field: Existence, Universality, and Detection

The electron mass shift in a laser field has long remained an elusive concept. We show that the mass shift can exist in pulses but that it is neither unique nor universal: it can be reduced by pulse shaping. We show also that the detection of mass shift effects in laser-particle scattering experiments is feasible with current technology, even allowing for the transverse structure of realistic beams.

Electron mass shift in nonthermal systems

The electron mass is known to be sensitive to local fluctuations in the electromagnetic field, and undergoes a small shift in a thermal field. It was claimed recently that a very large electron mass shift should be expected near the surface of a metal hydride (Widom and Larsen 2006 Eur. Phys. J. C 46 107). We examine the shift using a formulation based on the Coulomb gauge, which leads to a much smaller shift. The maximization of the electron mass shift under nonequilibrium conditions seems nonetheless to be an interesting problem. We consider a scheme in which a current in a hollow wire produces a large vector potential in the wire centre. Fluctuations in an LC circuit with nearly matched loss and gain can produce large current fluctuations; and these can increase the electron mass shift by orders of magnitude over its room temperature value.

RELATIVISTIC QUANTUM FIELD THEORY FOR CONDENSED SYSTEMS (II): RENORMALIZATION PROCEDURE

We proposed Atomic Schwinger–Dyson method (ASD method) in previous paper, which was a nonperturbative and relativistic quantum field theory for a finite baryon density. We think it is important to show the significance of renormarization in order to get real physical predictions. Moreover, the real value of physical mass, electric charge and wave function are completely different from those of the non-renormalized electron and photon in mean field theory, since there are many of the particle-antiparticle creations and annihilations, particle-hole excitation, and Pauli blocking, which give an effect on bare mass, electric charge, polarization of vacuum, and self-energy. In this paper, we shows that ASD method is renormalizable theory, and that photon condensation of ASD method gave rise to Coulomb's potential and the mass shift of electron. The interacting photon and electron fields, which have physical mass and electric charge, are expressed as generalized free field equations by using the mass shift and the self-energy of those particles. We obtain the expression of an exact solution of these particles on the basis of the Green functional method.

Relativistic theory of atom-laser interactions at very high laser intensities

The high-frequency approximation of Kristic and Mittleman is considered in detail as a basis for the relativistic theory of atom-laser interactions. The properties of the 3D potentials are discussed. Within a one-dimensional model similar to that employed by Kylstra, Ermolaev, and Joachain in ab initio calculations on the time-dependent Dirac equation, the electron mass-shift due to dressing by a superstrong laser field is investigated. In the full domain of the laser parameters, the frequency ω and the peak field strength ℰ0, the 1D bound states exhibit remarkable features. The numerical calculations show the existence of a very wide intermediate range of the field strengths where, in the zeroth order of the high-frequency approximation, the binding is stabilized by the field.

The mass shift of an electron in an electric field and its connection with the infrared problem in QED

Abstract The main purpose of this talk is to acquaint the audience with interesting properties of the mass shift of electron in a homogeneous constant field, especially with its classical asymtotics arising at small quantum parameters (2), when β1,β2, χ≪1. The unusual properties of this shift are: classicity and at the same time its absence in classical Abraham-Lorentz-Dirac equation; nonlocality expressing formation on the length ∼mc 2/eϵ much greater than Compton length h/mc; linearity in the modulus of eϵ, i.e. nonanalyticity and, consequently, nonperturbativity in the external field ϵ independence of spin of a particle but dependence on spin of proper field. Although the shift does not change the classical equation of motion, it does alter the action and should therefore manifest itself in quantum-mechanical processes. For example, in pair creation by electric field in vacuum described by imaginary part of Lagrange function of external field. It is shown also that due to locality, causality and unitar...

Finite-temperature and -density effects on electron self-mass and primordial nucleosynthesis.

The problem of renormalization in QED is examined for finite density and zero temperature. The effects of electron mass shift at a finite temperature on certain parameters of primordial nucleosynthesis are also studied. It is shown that these parameters are modified at high temperatures.

Production of Electron Pairs from a Zero-Mass State

Results are presented for the production of electron pairs by the collision of high-energy bremsstrahlung and high-intensity laser beams. With Stanford linear accelerator bremsstrahlung parameters, it is found that the laser must be focused to about ${10}^{18}$ W/${\mathrm{cm}}^{2}$ to produce pairs. Approximately 25 laser photons participate in each event, and the required laser intensity is outside the known radius of convergence of perturbation theory for this process. The electron mass shift may also be determined.

Search for an Electron Mass Shift inCs133in an Intense Electromagnetic Field

The possibility that the mass of a bound electron changes when placed in an intense electromagnetic field is studied here both theoretically and experimentally. The atomic-beam magnetic-resonance technique was used to examine hyperfine-structure frequency shifts in $^{133}\mathrm{Cs}$ that occur when the atom is subjected to an intense, nonresonant radio-frequency magnetic field perpendicular to the static "C" field. A 2921-MHz T${\mathrm{M}}_{010}$ cavity produced the perturbing field and was situated between Ramsey separated oscillatory loops, which induced the resonant transitions of interest. Shifts were observed for six $\ensuremath{\Delta}{m}_{F}=\ifmmode\pm\else\textpm\fi{}1$ transitions at field-independent points. No evidence was found for an electron mass shift. Good agreement is found between all observed shifts and those expected from a multilevel Bloch-Siegert effect.

Evidence of electron mass-shift in the forward scattered radiation from a laser-air spark

A simple mechanism is suggested to correlate the mass-shift effect of an electron in a laser beam with the frequency shift of the forward scattered radiation from a laser-air spark. Estimation gives 〈Δm〉 m ≈ 1.3 × 10 −4 according to the experimental observation.