Fall 2007

X-Ray Demolition Derby

An X-ray dislodges an outer-shell electron of a nitrogen molecule, with enough e

X-rays are notorious for damaging molecules, including those in our bodies. High in the upper atmosphere, X-rays from the Sun break apart simple molecules like nitrogen (N₂) and drive chemical reactions affecting the Earth. For these reasons, it’s important to understand exactly how radiation interacts with, damages, or destroys specific chemicals. Read more »

Reflection Grisms; For Fast Light that’s Just Right

Reflection grisms are efficient laser pulse compressors, making femtosecond lase

Fellows Ralph Jimenez and Henry Kapteyn and their groups recently helped develop optical technology that will make femtosecond laser experiments much simpler to perform, opening the door to using such lasers in many more laboratories. Read more »

A Failure to Communicate

In this lattice array, different phases of condensate wave functions are represe

In the quantum world inside Fellow Eric Cornell’s lab, communication occurs across a two-dimensional lattice array of Bose-Einstein condensates (BECs) when atoms tunnel out of superatoms (made from about 7000 garden-variety rubidium (Rb) atoms) into neighboring BECs. This communication keeps the array coherent, i.e., the phases of all condensates remain locked to each other. But something interesting happens when the tiny superatoms stop communicating among themselves. Vortices form. And how many appear depends on temperature. Read more »

Echoes of Hidden Worlds

Artist’s concept of excitons confined in two-dimensional quantum wells inside a

In Fellow Steve Cundiff’s lab, echoes of light are illuminating the quantum world. Former Graduate Student Gina Lorenz used a technique known as echo peak shift spectroscopy to probe the interactions of potassium atoms in a dense vapor. Research Associate Sam Carter then used the same method to investigate the interactions of excitons confined in two-dimensional semiconductor quantum wells. Read more »

Discovering New Planets

Planetfinder screen shot. Credit: Dick McCray

In JILA Fellow Dick McCray’s view, the way students learn astronomy is nearly the reverse of the way early astronomers learned astronomy. For instance, students might first learn Newton’s law of gravity and Kepler’s laws of planetary motion and then complete exercises in which they calculate what scientists have observed. But that’s not how Kepler did it. He fit observations of planetary motion with a controversial mathematical model that was much later confirmed to be correct by Newton’s theory of gravity. Read more »