Laser stabilization to neutral Yb in a discharge with polarization-enhanced frequency modulation spectroscopy.

Isotope selective optical excitation of atoms is important for experiments with neutral atoms, metrology, and work with trapped ions, including quantum information processing. Polarization-enhanced absorption spectroscopy is used to frequency stabilize a tunable external cavity laser diode system at 398.9 nm for isotope selective photoionization of neutral Yb atoms.

Observing electron localization in a dissociating H molecule in real time.

Dissociation of diatomic molecules with odd number of electrons always causes the unpaired electron to localize on one of the two resulting atomic fragments. In the simplest diatomic molecule H dissociation yields a hydrogen atom and a proton with the sole electron ending up on one of the two nuclei. That is equivalent to breaking of a chemical bond-the most fundamental chemical process.

The interaction of excited atoms and few-cycle laser pulses.

This work describes the first observations of the ionisation of neon in a metastable atomic state utilising a strong-field, few-cycle light pulse. We compare the observations to theoretical predictions based on the Ammosov-Delone-Krainov (ADK) theory and a solution to the time-dependent Schrödinger equation (TDSE). The TDSE provides better agreement with the experimental data than the ADK theory.

Isotope Effect in Tunneling Ionization of Neutral Hydrogen Molecules.

It has been recently predicted theoretically that due to nuclear motion light and heavy hydrogen molecules exposed to strong electric field should exhibit substantially different tunneling ionization rates [O. I. Tolstikhin, H.

Precise and Accurate Measurements of Strong-Field Photoionization and a Transferable Laser Intensity Calibration Standard.

Ionization of atoms and molecules in strong laser fields is a fundamental process in many fields of research, especially in the emerging field of attosecond science. So far, demonstrably accurate data have only been acquired for atomic hydrogen (H), a species that is accessible to few investigators. Here, we present measurements of the ionization yield for argon, krypton, and xenon with percent-level accuracy, calibrated using H, in a laser regime widely used in attosecond science.

Ultrafast, high repetition rate, ultraviolet, fiber-laser-based source: application towards Yb fast quantum-logic.

Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.

Transverse electron momentum distribution in tunneling and over the barrier ionization by laser pulses with varying ellipticity.

We study transverse electron momentum distribution in strong field atomic ionization driven by laser pulses with varying ellipticity. We show, both experimentally and theoretically, that the transverse electron momentum distribution in the tunneling and over the barrier ionization regimes evolves in a qualitatively different way when the ellipticity parameter describing polarization state of the driving laser pulse increases.

Anomalous Fluorescence Enhancement from Double Heterostructure 3D Colloidal Photonic Crystals--A Multifunctional Fluorescence-Based Sensor Platform.

Augmenting fluorescence intensity is of vital importance to the development of chemical and biochemical sensing, imaging and miniature light sources. Here we report an unprecedented fluorescence enhancement with a novel architecture of multilayer three-dimensional colloidal photonic crystals self-assembled from polystyrene spheres. The new technique uses a double heterostructure, which comprises a top and a bottom layer with a periodicity overlapping the excitation wavelength (E) of the emitters, and a middle layer with a periodicity matching the fluorescence wavelength (F) and a thickness that supports constructive interference for the excitation wavelength.

Experimental observation of the elusive double-peak structure in R-dependent strong-field ionization rate of H2(+).

When a diatomic molecule is ionized by an intense laser field, the ionization rate depends very strongly on the inter-nuclear separation. That dependence exhibits a pronounced maximum at the inter-nuclear separation known as the "critical distance". This phenomenon was first demonstrated theoretically in H2(+) and became known as "charge-resonance enhanced ionization" (CREI, in reference to a proposed physical mechanism) or simply "enhanced ionization"(EI).

Detection-enhanced steady state entanglement with ions.

Driven dissipative steady state entanglement schemes take advantage of coupling to the environment to robustly prepare highly entangled states. We present a scheme for two trapped ions to generate a maximally entangled steady state with fidelity above 0.99, appropriate for use in quantum protocols.

Picosecond 554 nm yellow-green fiber laser source with average power over 1 W.

We demonstrate a source of 554 nm pulses with 2.7 ps pulse duration and 1.41 W average power, at a repetition rate of 300 MHz.

Controllable optical phase shift over one radian from a single isolated atom.

Fundamental optics such as lenses and prisms work by applying phase shifts of several radians to incoming light, and rapid control of such phase shifts is crucial to telecommunications. However, large, controllable optical phase shifts have remained elusive for isolated quantum systems. We have used a single trapped atomic ion to induce and measure a large optical phase shift of 1.

Extreme ultraviolet interferometer using high-order harmonic generation from successive sources.

We present a new interferometer technique whereby multiple extreme ultraviolet light pulses are generated at different positions within a single laser focus (i.e., from successive sources) with a highly controllable time delay.

Absorption imaging of a single atom.

Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging.

Quantum interface between an electrical circuit and a single atom.

We show how to bridge the divide between atomic systems and electronic devices by engineering a coupling between the motion of a single ion and the quantized electric field of a resonant circuit. Our method can be used to couple the internal state of an ion to the quantized circuit with the same speed as the internal-state coupling between two ions. All the well-known quantum information protocols linking ion internal and motional states can be converted to protocols between circuit photons and ion internal states.

Phase-coherent repetition rate multiplication of a mode-locked laser from 40 MHz to 1 GHz by injection locking.

We have used injection locking to multiply the repetition rate of a passively mode-locked femtosecond fiber laser from 40 MHz to 1 GHz while preserving optical phase coherence between the master laser and the slave output. The system is implemented almost completely in fiber and incorporates gain and passive saturable absorption. The slave repetition rate is set to a rational harmonic of the master repetition rate, inducing pulse formation at the least common multiple of the master and slave repetition rates.

Experimental ionization of atomic hydrogen with few-cycle pulses.

We present experimental data on strong-field ionization of atomic hydrogen by few-cycle laser pulses. We obtain quantitative agreement at the 10% level between the data and an ab initio simulation over a wide range of laser intensities and electron energies.

Quantum optical waveform conversion.

Proposals for long-distance quantum communication rely on the entanglement of matter-based quantum nodes through optical communications channels, but the entangling light pulses have poor temporal behavior in current experiments. Here we show that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform while preserving all quantum properties, including entanglement. Our scheme paves the way for quantum communication at the full data rate of optical telecommunications.

Wavelength-scale imaging of trapped ions using a phase Fresnel lens.

A microfabricated phase Fresnel lens was used to image ytterbium ions trapped in a radio frequency Paul trap. The ions were laser cooled close to the Doppler limit on the 369.5 nm transition, reducing the ion motion so that each ion formed a near point source.

Imaging of trapped ions with a microfabricated optic for quantum information processing.

Trapped ions are a leading system for realizing quantum information processing (QIP). Most of the technologies required for implementing large-scale trapped-ion QIP have been demonstrated, with one key exception: a massively parallel ion-photon interconnect. Arrays of microfabricated phase Fresnel lenses (PFL) are a promising interconnect solution that is readily integrated with ion trap arrays for large-scale QIP.

Self-focusing in air with phase-stabilized few-cycle light pulses.

We investigate the nonlinear optical phenomenon of self-focusing in air with phase-stabilized few-cycle light pulses. This investigation looks at the role of the carrier-envelope phase by observing a filament in air, a nonlinear phenomenon that can be utilized for few-cycle pulse compression [Appl. Phys.

Mode-locked picosecond pulse generation from an octave-spanning supercontinuum.

We generate mode-locked picosecond pulses near 1110 nm by spectrally slicing and reamplifying an octave-spanning supercontinuum source pumped at 1550 nm. The 1110 nm pulses are near transform-limited, with 1.7 ps duration over their 1.

An automated submicron beam profiler for characterization of high numerical aperture optics.

An automated, interferometrically referenced scanning knife-edge beam profiler with submicron resolution is demonstrated by directly measuring the focusing properties of three aspheric lenses with numerical aperture (NA) between 0.53 and 0.68, with spatial resolution of 0.

Efficient generation of >2 W of green light by single-pass frequency doubling in PPMgLN.

We report 32% efficient frequency doubling of single-frequency 1029 nm light to green light at 514.5 nm using a single-pass configuration. A congruent composition, periodically poled magnesium-doped lithium niobate (PPMgLN) crystal of 50 mm length was used to generate a second-harmonic power of 2.