Shapiro, Shepard, and Wong [Phys. Rev. Lett. 62, 2377 (1989)] suggested that a scheme of multiple phase measurements, using quantum states with minimum ‘‘reciprocal peak likelihood,’’ could achieve a phase sensitivity scaling as 1/${\mathit{N}}_{\mathrm{tot}}^2$, where ${\mathit{N}}_{\mathrm{tot}}$ is the mean number of photons availavle for all measurements. We have simulated their scheme for as many as 240 measurements and have found optimum phase sensitivities for 3≤${\mathit{N}}_{\mathrm{tot}}$≤120. A power-law fit to the simulated data yields a phase sensitivity that scales as 1/${\mathit{N}}_{\mathrm{tot}}^{0.85\pm 0.01}$. We conclude that reciprocal peak likelihood is not a good measure of sensitivity.

The dynamo mechanism for generating the magnetic fields of galaxies requires the existence of a primordial seed field, which induces oscillations between the left- and right-handed Dirac neutrinos. We consider the excitation of the right-handed neutrinos in the early Universe due to these oscillations and show that nucleosynthesis sets stringent upper limit on the size of the neutrino magnetic moments: ${\mathrm{\mu }}_{\nu }$≲6.5×${10}^{\mathrm{-}34}$${\mathrm{\mu }}_{\mathit{B}}$ [1 G/${\mathit{B}}_{\mathrm{seed}}$(${\mathit{T}}_{\mathrm{now}}$)]. In the standard model these limits can be translated to a constraint on the neutrino masses, given by ${\mathit{tsumm}}_{\nu \mathit{i}}$(2.1×${10}^{\mathrm{-}15}$ eV) [1 G/${\mathit{B}}_{\mathrm{seed}}$(${\mathit{T}}_{\mathrm{now}}$)]. We also set upper limits on the transition magnetic moments.

We search for the rare decay ${\mathit{W}}^{\pm }$→γ${\mathrm{\pi }}^{\pm }$ in 4.2 ${\mathrm{pb}}^{\mathrm{-}1}$ of pp¯ collisions recorded with the Collider Detector at Fermilab. At the 95% confidence level, we find an upper limit on the partial decay width to be Γ(${\mathit{W}}^{\pm }$→γ${\mathrm{\pi }}^{\pm }$)/Γ(${\mathit{W}}^{\pm }$→${\mathit{e}}^{\pm }$ν)≤7.5×${10}^{\mathrm{-}3}$.

Bound-state ${\mathrm{\beta }}^{\mathrm{-}}$ decay was observed for the fist time by storing bare ${}_{66}{}^{163}{}_{}{}^{}\mathrm{Dy}_{}^{66+}{}_{}{}^{}$ ions in a heavy-ion storage ring. From the number of ${}_{67}{}^{163}{}_{}{}^{}\mathrm{Ho}_{}^{66+}{}_{}{}^{}$ daughter ions, measured as a function of the storage time, a half-life of ${47}_{\mathrm{-}5}^{+5\mathrm{}}$ d was derived. By comparing this result with reported half-lives for electron capture (EC) from the ${\mathit{M}}_1$ and ${\mathit{M}}_2$ shells of neutral ${}_{67}{}^{163}{}_{}{}^{}\mathrm{Ho}$, bounds for both the ${\mathit{Q}}_{\mathrm{EC}}$ value of neutral ${}_{67}{}^{163}{}_{}{}^{}\mathrm{Ho}$ and for the electron-neutrino mass were set.

We present observations of a spontaneous-force optical trap in which rubidium atoms are spin polarized by optical pumping. Stable trapping is achieved in two dimensions by the same force as in the Zeeman-shift optical trap, and in the third dimension by a macroscopic vortex force that is insensitive to light polarizations and magnetic fields. When the light along this third direction is circularly polarized and a parallel magnetic field is applied, the atoms become spin polarized.

A pulse shaping strategy is developed for exciting the ground-surface vibrational motion while minimizing radiation damage. The scheme is based on a resonant impulsive stimulated Raman scattering process where the amount of population transferred to the excited surface is strictly controlled. The scenario begins with an impulsive pulse which creates an instantaneous dipole moment. It follows by a pulse 180° out of phase with the instantaneous dipole which deposits vibrational energy into the ground electronic surface while blocking population transfer to the excited surface.

We report the first observation of high-order harmonic waves from rare-gas-like ions excited by a subpicosecond KrF excimer laser. At an intensity of ${10}^{15}$ W/${\mathrm{cm}}^2$, the highest orders of observed harmonics are the ninth (27.6 nm) in ${\mathrm{Li}}^{+}$, the eleventh (22.6 nm) in ${\mathrm{Na}}^{+}$, and the thirteenth (19.1 nm) in ${\mathrm{K}}^{+}$. The advantage of such ions as nonlinear media for extreme ultraviolet generation is discussed in relation to ionization potentials.

The transition from quasiperiodicity to chaos is studied in a two-dimensional dissipative map with the inverse-golden-mean rotation number. On the basis of a decimation scheme, it is argued that the (minimal) slope of the critical iterated circle map is proportional to the effective Jacobian determinant. Approaching the zero-Jacobian-determinant limit, the factor of proportion becomes a universal constant. Numerical investigation on the dissipative standard map suggests that this universal number could become observable in experiments.

We study the fluctuation properties of $0^{+}$ levels in rotational nuclei using the framework of SU(3) dynamical symmetry of the interacting boson model. Computations of Poincaré sections for SU(3) dynamical symmetry and its breaking confirm the expected relation between dynamical symmetry and classical chaos. On the other hand, the quantal energy level statistics in the realistic case of rotational nuclei is close to Gaussian-orthogonal-ensemble statistics, contrary to expectations. The conjectured relation between energy fluctuations and chaos is approached asymptotically. Several predictions for chaotic behavior of normally deformed and superdeformed rotational nuclei are given.

A class of strongly chaotic systems revealing a strange arithmetical structure is discussed whose quantal energy levels exhibit level attraction rather than repulsion. As an example, the nearest-neighbor level spacings for Artin’s billiard have been computed in a large energy range. It is shown that the observed violation of universality has its root in the existence of an infinite number of Hermitian operators (Hecke operators) which commute with the Hamiltonian and generate nongeneric correlations in the eigenfunctions.

Two intersecting laser beams of orthogonal circular polarization near resonant to the homogeneously broadened D1 transition of Na vapor were observed to deflect each other upon contact. The experimental results are in good agreement with calculations based on a model which includes diffraction and a local nonlinear atomic susceptibility wihch fully takes into account saturation and optical pumping effects. The contact deflection (or ‘‘bouncing’’) was also observed when both beams were tuned to the atomic resonance frequency.

An analytical model of three-dimensional Euler flows which exhibits a finite-time singularity is given. The singularity in vorticity occurs at a velocity field null (stagnation point) which lies on the line joining two vorticity field nulls. It is shown that the vorticity diverges inversely with time.

A two-dimensional, axisymmetric, relativistic fluid model describing the propagation of intense laser pulses in plasmas is formulated and numerically evaluated. Relativistic guiding is ineffective in preventing the diffractive spreading of short laser pulses and long pulses become modulated due to relativistic and wake-field effects. Laser pulses can be propagated over many Rayleigh lengths by use of a performed plasma density channel or by tailoring the pulse profile. Ultrahigh axial electric fields can be generated behind the laser pulse.

The propagation of laser pulses of intensity which is large enough for relativistic self-focusing to occur is strongy affected by Raman instabilities. Both large and small angle scattering are important. The latter is the most severe since it couples with relativistic self-focusing leading the pulses to acquire significant axial and transverse structure in a time of the order of the self-focusing time. This prevents smooth self-focused pulses propagation for distances longer than the Rayleigh length except for pulse duration of the order of the plasma period.

The typical MHD disruption at safety factor ${\mathit{q}}_{\mathit{a}}$=3 has been suppressed by off-central electron cyclotron heating with power of 70–80 kW in the JFT-2M tokamak. For the suppression, the electron cyclotron resonance layer has to be placed radially in a very narrow region of width about 1 cm near the q=2 surface. The observed narrow suppression window suggests that the basic mechanism responsible for the suppression is direct island heating. The actual time scale of the suppression is much faster than the time scale of the change of the overall current profile.

Experiments have been conducted on the LSX device where plasmas confined in a field-reversed magnetic geometry have exhibited record energy, particle, and configuration lifetimes. The scaling from previous smaller devices showed a very positive confinement scaling with s, the number of ion gyroradii inside the field-reversed configuration. These plasmas were observed to have gross stability to global low-order modes such as the internal tilt. The growth of tilt instabilities were not observed during the equilibrium decay of plasmas up to s∼8.

Rapid changes of the main ion energy distribution at transitions from L to H, H to L, and during edge localized modes (ELMs) are studied with the time-of-flight neutral measurement on the JFT-2M tokamak. At the L to H transition, 200–400 μs prior to the start of the ${\mathrm{H}}_{\mathrm{\alpha }}$ drop, an increase of the high-energy outflux above an energy of 200 eV is observed. An energy of more than 200 eV for hydrogen corresponds to the collisionless condition ${\nu }_{\mathrm{*}\mathit{i}}$<1 just inside the separatrix. A change of the energy distribution preceding that of the ${\mathrm{H}}_{\mathrm{\alpha }}$ signal is also found for ELMs.

The elastic properties of α-quartz are studied as a function of pressure using both a classical interatomic potential, and a first-principles pseudopotential approach. In both cases, we find that the structure becomes mechanically unstable at about 30 GPa. Our results suggest that the amorphization of quartz observed experimentally in this pressure range is triggered by the onset of a lattice shear instability. We analyze the microscopic origin of the elastic softening, and relate to the presence of an oxygen close-packed cubic arrangement in the quartz high-pressure structure. A change in the Si coordination is found to be intimately related to the shear instability.

Two reconstructions of the 90° partial dislocation core in silicon have been investigated using ab initio total-energy pseudopotential calculations. The asymmetric fourfold-coordinated configuration is shown to be stable and to be associated with only shallow states in the band gap. The symmetric quasi-fivefold-coordinated configuration is found to be metastable and to be associated with states that span the band gap. These results are reproduced with tight-binding Hamiltonians if the range of hopping integrals is restricted to include no more than four nearest neighbors.

We report results of an angle-resolved photoemission study to elucidate the driving mechanism of the Mo(001) surface reconstruction. We find, for the first time, a remarkable change of the shapes of Fermi contours upon cooling, which reveals a significant nesting at ${\mathit{k}}_{\mathrm{\parallel }}$=0.65 A${\mathrm{̊}}^{\mathrm{-}1}$, extended 0.30 A${\mathrm{̊}}^{\mathrm{-}1}$ perpendicular to the Σ¯ axis. The results suggest that the reconstruction should occur essentially by Peierls-type 2${\mathit{k}}_{\mathit{F}}$ instabilities with significant matrix-element effects.