Showing papers in "Physical Review Letters in 1982"
TL;DR: In this paper, a simple way has been discovered to put model pseudopotentials, $V(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}}), into a form which reduces the number of integrals required for an energy-band calculation from ϵ(n+1) to ϵ (n+2) for each $l$ in the sum.
Abstract: A simple way has been discovered to put model pseudopotentials, $V(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})={\ensuremath{\Sigma}}_{\mathrm{lm}}|{Y}_{\mathrm{lm}}〉{V}_{l}(r)\ifmmode\times\else\texttimes\fi{}〈{Y}_{\mathrm{lm}}|$, into a form which reduces the number of integrals of $V(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})$ required for an energyband calculation from $\frac{\mathrm{mn}(n+1)}{2}$ to $\mathrm{mn}$ for each $l$ in the sum (where $n$ is the number of plane waves used in the expansion and $m$ the number of points in the Brillouin zone at which the calculation is performed). The new form may be chosen to improve the accuracy of the pseudopotential when used in other chemical environments.
4,301 citations
TL;DR: In this article, the treatment of first-order phase transitions for standard grand unified theories is shown to break down for models with radiatively induced spontaneous symmetry breaking, leading to an explanation of the cosmological homogeneity, flatness, and monopole puzzles.
Abstract: The treatment of first-order phase transitions for standard grand unified theories is shown to break down for models with radiatively induced spontaneous symmetry breaking. It is argued that proper analysis of these transitions which would take place in the early history of the universe can lead to an explanation of the cosmological homogeneity, flatness, and monopole puzzles.
4,298 citations
IBM1
TL;DR: In this paper, surface microscopy using vacuum tunneling has been demonstrated for the first time, and topographic pictures of surfaces on an atomic scale have been obtained for CaIrSn 4 and Au.
Abstract: Surface microscopy using vacuum tunneling is demonstrated for the first time. Topographic pictures of surfaces on an atomic scale have been obtained. Examples of resolved monoatomic steps and surface reconstructions are shown for (110) surfaces of CaIrSn 4 and Au.
4,290 citations
TL;DR: The formation of a Wigner solid or charge-density-wave state with triangular symmetry is suggested as a possible explanation for the formation of the Hall plateau in magnetotransport of high-mobility, two-dimensional electrons as mentioned in this paper.
Abstract: A quantized Hall plateau of ${\ensuremath{\rho}}_{\mathrm{xy}}=\frac{3h}{{e}^{2}}$, accompanied by a minimum in ${\ensuremath{\rho}}_{\mathrm{xx}}$, was observed at $Tl5$ K in magnetotransport of high-mobility, two-dimensional electrons, when the lowest-energy, spin-polarized Landau level is $\frac{1}{3}$ filled. The formation of a Wigner solid or charge-density-wave state with triangular symmetry is suggested as a possible explanation.
3,528 citations
TL;DR: In this article, the relationship of linear polarizations of pairs of photons was measured with time-varying analyzers, and the results were in good agreement with quantum mechanical predictions but violate Bell's inequalities by 5 standard deviations.
Abstract: Correlations of linear polarizations of pairs of photons have been measured with time-varying analyzers. The analyzer in each leg of the apparatus is an acousto-optical switch followed by two linear polarizers. The switches operate at incommensurate frequencies near 50 MHz. Each analyzer amounts to a polarizer which jumps between two orientations in a time short compared with the photon transit time. The results are in good agreement with quantum mechanical predictions but violate Bell's inequalities by 5 standard deviations.
3,302 citations
TL;DR: The Hohenberg-Kohn theorem was extended to fractional electron number for an isolated open system described by a statistical mixture in this article, and the curve of lowest average energy was found to be a series of straight line segments with slope discontinuities at integral $N.
Abstract: The Hohenberg-Kohn theorem is extended to fractional electron number $N$, for an isolated open system described by a statistical mixture. The curve of lowest average energy ${E}_{N}$ versus $N$ is found to be a series of straight line segments with slope discontinuities at integral $N$. As $N$ increases through an integer $M$, the chemical potential and the highest occupied Kohn-Sham orbital energy both jump from ${E}_{M}\ensuremath{-}{E}_{M\ensuremath{-}1}$ to ${E}_{M+1}\ensuremath{-}{E}_{M}$. The exchange-correlation potential $\frac{\ensuremath{\delta}{E}_{\mathrm{xc}}}{\ensuremath{\delta}n(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}$ jumps by the same constant, and $\frac{{\mathrm{lim}}_{r\ensuremath{\rightarrow}\ensuremath{\infty}}\ensuremath{\delta}{E}_{\mathrm{xc}}}{\ensuremath{\delta}n(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}g~0$.
2,427 citations
TL;DR: In this article, the linear-polarization correlation of pairs of photons emitted in a radiative cascade of calcium has been measured using two-channel polarizers (i.e., optical analogs of Stern-Gerlach filters).
Abstract: The linear-polarization correlation of pairs of photons emitted in a radiative cascade of calcium has been measured. The new experimental scheme, using two-channel polarizers (i.e., optical analogs of Stern-Gerlach filters), is a straightforward transposition of Einstein-Podolsky-Rosen-Bohm gedankenexperiment. The present results, in excellent agreement with the quantum mechanical predictions, lead to the greatest violation of generalized Bell's inequalities ever achieved.
2,408 citations
TL;DR: The spectrum of density perturbations in the new-inflationary-universe scenario is calculated in this article, where the main source is the quantum fluctuations of the Higgs field, which lead to fluctuations in the time at which the false vacuum energy is released.
Abstract: The spectrum of density perturbations is calculated in the new-inflationary-universe scenario. The main source is the quantum fluctuations of the Higgs field, which lead to fluctuations in the time at which the false vacuum energy is released. The value of $\frac{\ensuremath{\delta}\ensuremath{\rho}}{\ensuremath{\rho}}$ on any given length scale $l$, at the time when the Hubble radius $\ensuremath{\gg}l$, is estimated. This quantity is nearly scale invariant (as desired), but is unfortunately about ${10}^{5}$ times too large.
2,054 citations
TL;DR: In this article, a new operational regime has been observed in neutral-injection-heated ASDEX divertor discharges, characterized by high aspect ratio values comparable to the aspect ratio of Ohmic discharges.
Abstract: A new operational regime has been observed in neutral-injection-heated ASDEX divertor discharges. This regime is characterized by high ${\ensuremath{\beta}}_{p}$ values comparable to the aspect ratio $A({\ensuremath{\beta}}_{p}l~0.65A)$ and by confinement times close to those of Ohmic discharges. The high-${\ensuremath{\beta}}_{p}$ regime develops at an injection power \ensuremath{\ge}1.9 MW, a mean density ${\overline{n}}_{e}g~3\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, and a $q(a)$ value \ensuremath{\ge}2.6. Beyond these limits or in discharges with material limiter, low ${\ensuremath{\beta}}_{p}$ values and reduced particle and energy confinement times are obtained compared to the Ohmic heating phase.
1,904 citations
TL;DR: In this article, the authors analyzed three-dimensional Yang-Mills and gravity theories augmented by gauge-invariant mass terms and quantized a dimensionless mass-couplingconstant ratio.
Abstract: Three-dimensional Yang-Mills and gravity theories augmented by gauge-invariant mass terms are analyzed. These topologically nontrivial additions profoundly alter the particle content of the models and lead to quantization of a dimensionless mass-coupling-constant ratio. The vector field excitations become massive, with spin 1 (rather than massless with spin 0), and the mass provides an infrared cutoff. The gravitation acquires mass, mediates finite-range interactions, and has spin 2 (rather than being absent altogether); although its mass term is of third derivative order, there are no ghosts or acausalities.
1,693 citations
TL;DR: In this paper, a locally supersymmetric grand unification program is proposed which couples the $N=1$ supergravity multiplet to an arbitrary grand unified gauge group with any number of left-handed chiral multiplets and a gauge vector multiplet.
Abstract: A locally supersymmetric grand unification program is proposed which couples the $N=1$ supergravity multiplet to an arbitrary grand unified gauge group with any number of left-handed chiral multiplets and a gauge vector multiplet. A specific model is discussed where it is shown that not only do the gravitational interactions eliminate the degeneracy of the vacuum state encountered in global supersymmetry, but simultaneously they can break both supersymmetry and SU(2) \ensuremath{\bigotimes} U(1) down to a residual $\mathrm{SU}{(3)}^{c}\ensuremath{\bigotimes}\mathrm{U}(1)$ symmetry at \ensuremath{\sim}300 GeV.
TL;DR: In this article, the statistics of two-particle quantum mechanics are discussed, and how this works for two-and three-dimensional quantum mechanics is discussed in the context of (2+1)-and (3+3)-models.
Abstract: Composites formed from charged particles and vortices in (2+1)-dimensional models, or flux tubes in three-dimensional models, can have any (fractional) angular momentum. The statistics of these objects, like their spin, interpolates continuously between the usual boson and fermion cases. How this works for two-particle quantum mechanics is discussed here.
TL;DR: In this paper, it was shown that the following statements about a quantum correlation experiment are mutually equivalent: (1) there is a deterministic hidden-variables model for the experiment, which is a factorizable, stochastic model.
Abstract: It is shown that the following statements about a quantum correlation experiment are mutually equivalent. (1) There is a deterministic hidden-variables model for the experiment. (2) There is a factorizable, stochastic model. (3) There is one joint distribution for all observables of the experiment, returning the experimental probabilities. (4) There are well-defined, compatible joint distributions for all pairs and triples of commuting and noncommuting observables. (5) The Bell inequalities hold.
TL;DR: In this paper, it was demonstrated that the orbital angular momentum of a particle of charge orbiting around a tube with magnetic flux is quantized in units in units of √ n = √ √ q √ 2 √ σ 2 σ σ + σ √ 1 σ − σ 1/σ 2/π σ.
Abstract: It is demonstrated that the orbital angular momentum ${l}_{z}$ of a particle of charge $q$ orbiting around a tube with magnetic flux $\ensuremath{\Phi}$ is quantized in units ${l}_{z}=\mathrm{integer}\ensuremath{-}\frac{q\ensuremath{\Phi}}{2\ensuremath{\pi}}$. A very simple physical argument for this is presented, and applied to understand the Dirac quantization condition and the charge-spin relation for particles bound to magnetic monopoles. The unusual statistics of flux-tube-charged-particle composites is discussed.
TL;DR: In this article, the chemical equilibrium time for gluons and light quarks was found to be less than 10−24$ sec in high-energy nuclear collisions, and the strangeness abundance saturates during the lifetime of the plasma created in high energy nuclear collisions.
Abstract: Rates are calculated for the processes $\mathrm{gg}\ensuremath{\rightarrow}s\overline{s}$ and $u\overline{u}$,$d\overline{d}\ensuremath{\rightarrow}s\overline{s}$ in highly excited quarkgluon plasma. For temperature $Tg~160$ MeV the strangeness abundance saturates during the lifetime (\ensuremath{\sim}${10}^{\ensuremath{-}23}$ sec) of the plasma created in high-energy nuclear collisions. The chemical equilibration time for gluons and light quarks is found to be less than ${10}^{\ensuremath{-}24}$ sec.
TL;DR: In this article, a two-dimensional spin model with cubic or isotropic symmetry is mapped onto a solid-on-solid model, which leads to an analytic calculation of the critical point and some critical indices.
Abstract: A two-dimensional $n$-component spin model with cubic or isotropic symmetry is mapped onto a solid-on-solid model. Subject to some plausible assumptions this leads to an analytic calculation of the critical point and some critical indices for $\ensuremath{-}2l~nl~2$.
TL;DR: In this paper, small-amplitude double layers and solitary waves containing magnetic-fieldaligned electric field components were observed for the first time in the auroral plasma between altitudes of 6000 and 8000 km in association with electron and ion velocity distributions that indicate the presence of electric fields parallel to the magnetic field.
Abstract: Small-amplitude double layers and solitary waves containing magnetic-field-aligned electric field components have been observed for the first time in the auroral plasma between altitudes of 6000 and 8000 km in association with electron and ion velocity distributions that indicate the presence of electric fields parallel to the magnetic field. The double layers may account for a large portion of the parallel potential drop that accelerates auroral particles.
TL;DR: In this article, it was shown that the factorization of disconnected Wilson loop amplitudes implies a major reduction in the dynamical degrees of freedom in the large-$N$ limit of lattice gauge theory; the original model may be replaced by a much simpler one.
Abstract: It is pointed out that the factorization of disconnected Wilson loop amplitudes implies a major reduction in the dynamical degrees of freedom in the large-$N$ limit of lattice gauge theory; the original model may be replaced by a much simpler one ($d$ is the space-time dimensionality), $Z=\ensuremath{\Pi}\stackrel{}{\ensuremath{\mu}}[\ensuremath{\int} d {U}_{\ensuremath{\mu}}\mathrm{exp}({\ensuremath{\beta}}_{\ensuremath{
u}\ensuremath{
e}}\ensuremath{\Sigma}\stackrel{d}{\ensuremath{\mu}\ensuremath{
e}\ensuremath{
u}=1}\mathrm{tr}{U}_{\ensuremath{\mu}}{U}_{v}{{U}_{\ensuremath{\mu}}}^{\ifmmode\dagger\else\textdagger\fi{}}{{U}_{\ensuremath{
u}}}^{\ifmmode\dagger\else\textdagger\fi{}})]$ Thus the field theory may be reduced to an integration over a finite number of matrices in large-$N$ limit.
IBM1
TL;DR: In this article, it was shown that at low modulation frequencies the traversing particle sees a static barrier and at high frequencies the particle tunnels through the time-averaged potential, but can do it inelastically, losing or gaining modulation quanta.
Abstract: One of several contradictory existing results for the time a tunneling particle interacts with its barrier is confirmed, by considering tunneling through a time-modulated barrier. At low modulation frequencies the traversing particle sees a static barrier. At high frequencies the particle tunnels through the time-averaged potential, but can do it inelastically, losing or gaining modulation quanta. The transition between the two regimes yields $\ensuremath{\int}\mathrm{dx}{[\frac{m}{2(V\ensuremath{-}E)}]}^{\frac{1}{2}}$ for the traversal time.
TL;DR: In this paper, it was shown that the local quasi-energy spectrum of the rotator problem is discrete and that its wave function is almost periodic in time, which allows one to understand on physical grounds some numerical results recently obtained in the context of rotator problems.
Abstract: A periodically kicked quantum rotator is related to the Anderson problem of conduction in a one-dimensional disordered lattice. Classically the second model is always chaotic, while the first is chaotic for some values of the parameters. With use of the Anderson-model result that all states are localized, it is concluded that the local quasienergy spectrum of the rotator problem is discrete and that its wave function is almost periodic in time. This allows one to understand on physical grounds some numerical results recently obtained in the context of the rotator problem.
TL;DR: In this article, the occurrence of sudden qualitative changes of chaotic (or "turbulent") dynamics is discussed and illustrated within the context of the one-dimensional quadratic map, and the cause and properties of these phenomena are investigated.
Abstract: The occurrence of sudden qualitative changes of chaotic (or "turbulent") dynamics is discussed and illustrated within the context of the one-dimensional quadratic map. For this case, the chaotic region can suddenly widen or disappear, and the cause and properties of these phenomena are investigated.
TL;DR: In this article, the deceleration and velocity bunching of Na atoms in an atomic beam have been observed, caused by absorption of counter-propagating resonant laser light.
Abstract: Deceleration and velocity bunching of Na atoms in an atomic beam have been observed. The deceleration, caused by absorption of counterpropagating resonant laser light, amounts to 40% of the initial thermal velocity, corresponding to about 15 000 absorptions. Atoms were kept in resonance with the laser by using a spatially varying magnetic field to provide a changing Zeeman shift to compensate for the changing Doppler shift as the atoms decelerated.
TL;DR: In this article, an exact sum rule is derived and used to estimate the threshold and cross section for the production of the new states in the teraelectronvolt energy region.
Abstract: If one assumes a spontaneously broken local supersymmetry, big-bang cosmology implies that the universe is filled with a gravitino (${g}_{\frac{3}{2}}$) gas---possibly its dominant constituent. From the observational bound on the cosmological mass density it follows that ${m}_{{g}_{\frac{3}{2}}}\ensuremath{\lesssim}1$ keV. Correspondingly, the supersymmetry breaking parameter $F$ satisfies $\sqrt{F}\ensuremath{\lesssim}2\ifmmode\times\else\texttimes\fi{}{10}^{3}$ TeV, requiring new supersymmetric physics in the teraelectronvolt energy region. An exact sum rule is derived and used to estimate the threshold and cross section for the production of the new states.
TL;DR: In this article, the authors introduce a small Z(N) breaking interaction into axion models without upsetting the Peccei-Quinn mechanism, which leads to galaxy formation.
Abstract: Axion models have a spontaneously broken Z{A) symmetry. The resulting discretely degenerate vacua and domain-wall solitons are incompatible with the standard cosmology. It is possible, however, to introduce a small Z(N) breaking interaction into axion models without upsetting the Peccei-Quinn mechanism. In that case the domain walls disappear a certain time after their formation in the early universe. Their. presence for a limited time period might lead to galaxy formation.
TL;DR: In this paper, the pulse velocity in the linear regime in samples of GaP: N with a laser tuned to the bound $A$-exciton line is measured with use of a picosecond time-of-flight technique.
Abstract: The pulse velocity in the linear regime in samples of GaP: N with a laser tuned to the bound $A$-exciton line is measured with use of a picosecond time-of-flight technique. The pulse is seen to propagate through the material with little pulse-shape distortion, and with an envelope velocity given by the group velocity even when the group velocity exceeds 3\ifmmode\times\else\texttimes\fi{}${10}^{10}$ cm/sec, $\mathrm{equals}\ifmmode\pm\else\textpm\fi{}\ensuremath{\infty}$, or becomes negative. The results verify the predictions of Garrett and McCumber.
TL;DR: A numerical analysis of the evolution of the Higgs expectation value and the temperature of the universe during the symmetry-breaking phase transition in an SU(5) theory with radiatively induced symmetry breaking is presented in this paper.
Abstract: A numerical analysis of the evolution of the Higgs expectation value and the temperature of the universe during the symmetry-breaking phase transition in an SU(5) theory with radiatively induced symmetry breaking is presented. It is shown that there is sufficient inflation (exponential expansion) to explain the cosmological homogeneity, isotropy, flatness, and monopole puzzles, and also that the universe reheats to a temperature $O({10}^{14} \mathrm{GeV})$ so that the usual scheme for baryogenesis can proceed.
TL;DR: In this article, the low-lying particlelike excitations of a model linearly conjugated diatomic polymer were found to be pairs of either spin-0 or spin-textonehalf solitons with irrational charge values, and the charge values and excitation energies were calculated as functions of the difference of the energy levels of the atomic $p$ orbitals of the two atomic constitutents of the unit cell.
Abstract: The low-lying particlelike excitations of a model linearly conjugated diatomic polymer, ${(A=B)}_{x}$, are found to be pairs of either spin-0 or spin-\textonehalf{} solitons with irrational charge values. The charge values and excitation energies are calculated as functions of the difference of the energy levels of the atomic $p$ orbitals of the two atomic constitutents of the unit cell. The phonon spectrum of the uniform polymer is also calculated.
TL;DR: The gravitino must be either light enough so that ambient gravitinos would not produce too large a cosmic deceleration, or heavy enough such that almost all gravitines would have decayed before the time of helium synthesis as discussed by the authors.
Abstract: The gravitino must be either light enough so that ambient gravitinos would not produce too large a cosmic deceleration, or heavy enough so that almost all gravitinos would have decayed before the time of helium synthesis. The second alternative is shown to allow supersymmetry-breaking scales above a model-dependent lower bound of ${10}^{11}$ to ${10}^{16}$ GeV.
TL;DR: In this paper, the authors show that the enhancement predicted by the particle plasmon model of surface-enhanced Raman scattering is limited by radiation damping, and that the damping becomes more severe as particle size increases.
Abstract: Theoretical calculations are presented which show that the enhancement predicted by the particle plasmon model of surface-enhanced Raman scattering is limited by radiation damping. The damping becomes more severe as particle size increases, while the enhancement produced by small particles is limited by surface scattering. Good agreement between theory and experimental measurements of the wavelength dependence of surface-enhanced Raman scattering on lithographically produced microstructures is found when radiation damping is taken into account.
TL;DR: In this article, the first experimental evidence of subharmonic bifurcations, generalized multistability, and chaotic behavior were found experimentally in a Q-switched CO/sub 2/ laser operating at 10.6 µm.
Abstract: Subharmonic bifurcations, generalized multistability, and chaotic behavior were found experimentally in a Q-switched CO/sub 2/ laser operating at 10.6 ..mu..m. Jumps between two strange attractors lead to a low-frequency (1/f type) divergence in the power spectrum. This is the first experimental evidence of these phenomena in a quantum-optical molecular system. A theoretical model is also presented whose results are in good agreement with the experimental data.