Atomic & Molecular Physics

A Quantum Leap for Precision Lasers

New ultrastable laser design. A "lasing" photon interacts with a chain of Sr ato

To be the best they can be, optical atomic clocks need better clock lasers — lasers that remain phase coherent a hundred times longer than the very best conventional lasers. For instance, light from the clock laser in Fellow Jun Ye’s lab can travel around the Earth 10 times before it loses coherence. However, realizing the potential of the lab’s optical clock requires that the laser light remain coherent for 1000 trips around the Earth. The brute force solution to this problem would be to operate the clock laser at 4 K. This approach would increase the cost, complexity, and size of the optical clock as well as rendering it impractical for space exploration and travel. Read more »

Qubits in Action

Two offices, i.e., Sr atoms, exchange information when they enter a mind meld (b

Fellows Ana Maria Rey and Jun Ye have come up with a clever idea that should make it much easier to design a quantum computer based on alkaline-earth atoms such as strontium (Sr). In this work, they collaborated with former research associate Marty Boyd, former JILA Fellow Peter Zoller (University of Innsbruck), and colleagues from Harvard University and the University of Innsbruck. Read more »

Collision Course

Four interacting ultracold fermions look like four cobras locked in an intricate

The Greene group just figured out everything you theoretically might want to know about four fermions "crashing" into each other at low energies. Low energies in this context mean ultracold temperatures under conditions where large, floppy Feshbach molecules form. The group decided to investigate four fermions because this number makes up the smallest ultracold few-body system exhibiting behaviors characteristic of the transition between Bose-Einstein condensation and superfluidity. Senior research associate José D’Incao, graduate student Seth Rittenhouse, former research associate Nirav Mehta, and Fellow Chris Greene participated in the study. Read more »

The Lab with the X-ray Eyes

Vibrating molecules of N2O4 emit a bright burst of X-rays when their N-N bond is

Experimental setup. Ultrafast laser pulses excite N2O4 molecules, then probe the

Researchers in the Kapteyn/Murnane group have decided to use soft X-ray bursts to watch the interplay of electronic and atomic motions inside a molecule. Such information determines how chemical bonds are formed or broken during chemical reactions.

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Fortune’s Bubbles Rise and Fall

A while back, former graduate student Scott Papp, graduate student Juan Pino, and Fellow Carl Wieman decided to see what would happen as they changed the magnetic field around a mixture of two different rubidium (Rb) isotopes during Bose-Einstein condensation. They assumed that the interactions between the atoms would change. They also expected they would observe two distinct condensates at some point. What they didn’t expect was the formation of alternating "bubbles" of ⁸⁵Rb and ⁸⁷Rb inside their cigar-shaped trap. Read more »

Beams In Collision

Cold collision studies show that the behavior of a He atom hitting a molecule of

Last year the Ye group conducted an actual laboratory astrophysics experiment. Graduate students Brian Sawyer, Ben Stuhl, and Mark Yeo, research associate Dajun Wang, and Fellow Jun Ye fired cold hydroxyl (OH) radicals into a linear decelerator equipped with an array of highly charged electrodes and slowed the OH molecules to a standstill. These molecules were then loaded into a permanent magnetic trap where they became the stationary target for collision studies. Next, Sawyer and his colleagues aimed supersonic beams of either helium (He) atoms or deuterium molecules (D₂) at the OH molecules. They then studied the resulting low-energy collisions, which took place at temperatures of 80–300 K. Read more »

Breaking Up Is Hard To Do

After a X-ray knocks an electron out of an O2 molecule, it takes more than 300 f

An oxygen molecule (O₂) doesn't fall apart so easily — even when an X-ray knocks out one of its electrons and superexcites the molecule during a process called photoionization. In this process, the X-ray first removes an electron from deep inside the molecule, leaving a hole in O₂⁺. Then, an outer electron can fall into the hole, and a second outer electron gets ejected, carrying away any excess energy. The loss of the second electron is known as autoionization, or Auger decay. Read more »

The Right Stuff

In a quantum computer, individual strontium atoms (qubits) will be held in a sto

In the summer of 2008, Fellow Jun Ye spent a couple of months at CalTech, where he ran into another visiting professor, former JILA Fellow Peter Zoller. Zoller left JILA in 1994 to become Professor of Physics at the University of Innsbruck (Austria). Besides riding bikes together in the mountains, the two men engaged in happy and fruitful discussions about Ye’s work developing a strontium- (Sr-) based optical atomic clock and Zoller’s pioneering research on quantum computing. It took them a matter of a couple of weeks to come up with a basic theoretical framework for a quantum computer based on alkaline-earth metals such as Sr. Read more »

Scientists with X-Ray Eyes

Margaret Murnane in her lab with a laser. Credit:The Kapteyn/Murnane Group

JILA scientists Margaret Murnane and Henry Kapteyn run a lab at JILA together. They’re also married to each other. They specialize in studying lasers and light. One of the things they like to do in the lab is watch what’s happening inside molecules. They’ve come up with a very clever way to do this. Read more »

The Polar Molecule Express

(Figure I.) Artist’s conception of a gas of ultracold 40K and 87Rb atoms at ~350

(Figure II.) Lowering the magnetic field leads to the creation of extremely loos

(Figure III.) Creation of ground-state polar molecules. Two lasers locked to dif

(Figure IV.) Ground-state polar molecules with permanent electric dipole moments

The Jin and Ye groups recently crafted an entirely new form of matter — tens of thousands of ultracold polar molecules in their lowest energy state. The ground-state molecules are too cold to exist naturally anywhere in the Universe. But, like the Bose-Einstein condensates discovered in the mid-1990s, they promise to open the door to unprecedented explorations of the quantum world, including quantum information processing and exquisite precision measurement. That these molecules exist at all is a testament to the clever ideas and persistence of the Jin and Ye groups.

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