Richard G. Brewer

Observation of superradiant and subradiant spontaneous emission of two trapped ions

Summary form only given. We report a laboratory realization of the gedanken experiment that Dicke used to introduce superradiance. Two Ba/sup +/ ions are laser-cooled and crystallized in a microscopic Paul trap so that they come to rest 1.5 microns from each other. This is about 3 wavelengths of the 493 nm light used to laser cool the transition. Micromotion and residual thermal motion are low so that they are essentially stationary relative to 493 nm light.

Optical Coherent Transients by Laser Frequency Switching

Coherence phenomena such as photon echoes, free induction, and nutation effects are easily detected in molecular iodine using a frequency-switched tunable cw dye laser. This technique is generally applicable to atoms, molecules, and solids and offers unique ways for probing dynamic interactions in a selective manner. Elastic and inelastic collision mechanisms for

SELF‐TRAPPING IN MEDIA WITH SATURATION OF THE NONLINEAR INDEX

{\mathrm{I}}_{2}

Role of laser damping in trapped ion crystals

are examined independently and compared with theory.

Nonlinear laser spectroscopy of CH3F at 3.39 microns

Numerical solutions of the nonlinear wave equation show that the steady‐state self‐trapping of optical beams in molecular fluids exhibits new characteristics when the intensity‐dependent index (orientational Kerr effect) begins to saturate. The power dependence of the beam diameter and the radial electric field distribution are examined. Beam diameters less than the wavelength of light are predicted for CS2 in the saturation regime.

Coherent Optical Transients.

Publisher Summary Cooling by laser radiation pressure is essential to reach the milliKelvin temperatures at which crystallization can occur. Cooling rates depend on array size and on the position of the ion in the array. Cooling rates can reverse sign so that heating occurs below resonance and cooling occurs above resonance. Cooling rates depend sensitively on trap parameters—for example, trap voltage and frequency. The inhibition of laser cooling is caused by Doppler shifts arising from radio frequency micromotion. Ions in an rf quadrupole trap undergo micromotion oscillations about their equilibrium position at the frequency of the rf trap voltage Ω. In ion arrays, substantial micromotion is always present to balance the mutual Coulomb repulsion of the ions. Micromotion amplitudes are comparable to the wavelength of the cooling radiation and strong Doppler shifts result. Micromotion Doppler shifts can reduce or even reverse the sign of laser cooling in ion crystals relative to single ions. This chapter describes a few experiments that demonstrate spectral broadening and the inhibition of laser cooling by micromotion.

Optical Coherent Transients by Laser Frequency-Switching

Abstract Stark-tuned nonlinear laser spectroscopy is applied to a few transitions in CH 3 F near 3.39 μ, with limiting linewidths of 100 kHz being observed. Dipole moments in excited vibrational states, as well as in the ground state, have been measured. Evidence for a new perpendicular band in this region is presented.

The Order-Chaos Transition of Two Trapped Ions

The early practitioners of nuclear magnetic resonance [1,2] probably never dreamed that their sophisticated coherence techniques would one day be adapted to the optical region. Coherent radiation sources were needed and in those days, the early 1950’s, lasers were not being discussed. We now know that the subject of coherent optical transients has developed steadily, beginning in 1964 with the initial photon echo measurement of Kurnit, Abella, and Hartmann [3]. Indeed, at the present time, the optical analogs of pulsed NMR transients have to some degree been realized.

Ultrahigh-finesse optical cavities

Coherence phenomena such as photon echoes, free induction and nutation effects are easily detected in molecular iodine using a frequency-switched tunable cw dye laser. This technique is generally applicable to atoms, molecules, and solids and offers unique ways for probing dynamic interactions in a selective manner. Elastic and inelastic collision mechanisms for I2 are examined independently and compared with theory.

Precision measurements of the lifetime of a single trapped ion with a nonlinear electro-optic switch

Publisher Summary Trapped particles can describe two very different kinds of motion: (1) small oscillations about equilibrium points in an ordered array and (2) disordered, apparently random motion. Transitions between those two types of motion could be induced by varying the trapping potential. This chapter describes order–chaos transitions in a deterministic dynamical system. Analysis of the extended trajectories shows the typical characteristics of deterministic chaos: the Fourier spectrum is continuous even though the system has only six degrees of freedom, and the largest Lyapunov exponent goes from zero in the quasiperiodic state to a positive value in the chaotic state. The chapter describes an experiment that shows the transition between ordered and chaotic motion for two trapped, laser-cooled barium ions. The ions were detected by scattered laser light at 493 nm together with a second laser at 650 nm that also cooled the ions. In the chaotic state, the fluorescence count rate drops dramatically due to the large Doppler effect.