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John Bohn

Content About: John Bohn

Published: 09/07/2017 - 1:15pm Type of Content: Article-Research Highlight

Researchers at JILA and around the world are starting a grand adventure of precisely controlling the internal and external quantum states of ultracold molecules after years of intense experimental and theoretical study. Such control of small molecules, which are the most complex quantum systems that can currently be completely understood from the principles of quantum mechanics, will allow...

Published: 03/13/2014 - 7:45am Type of Content: Article-Research Highlight

Quantum chaos just showed up in an ultracold gas of erbium atoms, and the Bohn theory group knows why. Theorists expect quantum chaos to appear when quantum mechanical objects get sufficiently complicated. But until now, scientists hadn’t realized that something as simple as a pair of colliding atoms could be complicated enough for quantum chaos to appear. For instance, the Bohn group has...

Published: 12/06/2013 - 7:43am Type of Content: Article-Research Highlight

Physicists wonder about some pretty strange things. For instance, one burning question is: How round is the electron? While the simplest picture of the electron is a perfect sphere, it is possible that it is instead shaped like an egg. The egg shape would look a bit like a tiny separation of positive and negative charges. Physicists call this kind of charge separation an electric dipole moment...

Published: 04/09/2013 - 1:01pm Type of Content: Article-Research Highlight

The Ye and Bohn groups have made a major advance in the quest to prepare “real-world” molecules at ultracold temperatures. As recently reported in Nature, graduate students Ben Stuhl and Mark Yeo, research associate Matt Hummon, and Fellow Jun Ye succeeded in cooling hydroxyl radical molecules (*OH) down to temperatures of no more than five thousandths of a degree above absolute zero (5mK)....

Published: 08/24/2011 - 6:00pm Type of Content: Article-Research Highlight

JILA’s quest to determine whether the electron has an electric dipole moment (eEDM) began in 2006 with a suggestion by Fellow Eric Cornell that the molecular ion hafnium fluoride (HfF+) might be well suited for an eEDM experiment. An electric dipole moment is a measure of the separation of positive and negative charges in a system. If an electron does have an electric dipole moment, it’s...

Published: 03/03/2015 - 9:32am Type of Content: Video Gallery

John Bohn (JILA), during FANO Memorial Symposium, "Resonances and Reflections: Profiles of Ugo Fano's Physics and Its Influences", held July 24, 2002 at The Institute for Theoretical, Atomic and Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts.

Published: 03/20/2011 - 6:00pm Type of Content: Article-Research Highlight

In 2008, the Ye and Jin groups succeeded in making ultracold potassium-rubidium (KRb) molecules in their ground state (See “Redefining Chemistry at JILA” in the Spring 2010 issue of JILA Light & Matter). Their next goal was to figure out how to precisely control chemical reactions of these ultracold polar molecules by manipulating the quantum states of the reactants. But first the...

Published: 02/23/2011 - 5:00pm Type of Content: Article-Research Highlight

Putting the brakes on a superfluid dipolar Bose-Einstein condensate (BEC) just got a whole lot more interesting. Last year, the Bohn theory group explored what would occur in a dipolar BEC when a laser probe — think of it like a finger — tickled a BEC just hard enough to excite a roton. (see JILA Light & Matter, Summer 2010).

The roton is a strange type of quasi...

Published: 08/17/2010 - 6:00pm Type of Content: Article-Research Highlight

The Bohn group has just come up with an exciting, really complicated experiment for someone else to do. This is something theorists like graduate student Ryan Wilson, former research associate Shai Ronen, and Fellow John Bohn get a kick out of. In this case, they’re recommending an experiment to measure how fast a tiny blue laser would have to move through a dipolar Bose-Einstein condensate (...

Published: 02/09/2010 - 5:00pm Type of Content: Article-Research Highlight

The race to measure the electron’s electric dipole moment (eEDM) is picking up speed across the world, thanks to graduate student Ed Meyer of JILA’s Lazy Bohn’s Ranch (i.e., John Bohn’s theory group). Meyer has identified more than a dozen horses, a.k.a. molecules and molecular ions, with strong enough internal electric fields to compete in the eEDM derby. Imperial...

Published: 04/08/2009 - 6:00pm Type of Content: Article-Research Highlight

Understanding how molecules collide is a hot topic in ultracold physics. Knowing the number of times molecules crash into each other and what happens when they do helps theorists predict the best ways to cool molecules to merely cold (1 K–1 mK), pretty cold (1 mK–1 µk), or ultracold (< 1 µK) temperatures.

Fellow John Bohn recently decided to investigate...

Published: 02/09/2009 - 5:00pm Type of Content: Article-Research Highlight

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...

Published: 09/29/2008 - 6:00pm Type of Content: Article-Research Highlight

The mission to find the electron electric dipole moment (eEDM) recently took a menacing turn. Chief Eric Cornell and his protégés were already hard at work characterizing the hafnium fluoride ion (HfF+). Their goal was to be the first in the world to complete the mission. In their choice of molecule, they owed a lot to JILA theorists Ed Meyer and John Bohn (a.k.a. Agents 13 and...

Published: 07/08/2008 - 6:00pm Type of Content: Article-Research Highlight

The John Bohn lab at JILA owes its very existence to a 2002 decision by the Colorado Rockies to begin storing baseballs in a room with ~50% humidity. The conventional wisdom at the time was that Denver’s thinner air was responsible for making Coors Field a hitter’s heaven. In mile-high Denver, hitters averaged two more home runs per game because the thinner air caused a given home run ball to...

Published: 04/08/2007 - 6:00pm Type of Content: Article-Research Highlight

A second wave has appeared on the horizon of ultracold atom research. Known as the p-wave, it is opening the door to probing rich new physics, including unexplored quantum phase transitions. The first wave of ultracold atom research focused on s-wave pairing between atoms, where the “s” meant the resultant molecules are not rotating. In contrast, p-waves involve higher-order...

Published: 04/08/2007 - 6:00pm Type of Content: Article-Research Highlight

Researchers from the Ye, Bohn, and Greene groups are busy exploring a cold new world crawling with polar hydroxyl radical (OH) molecules. The JILA experimentalists have already discovered how to cool OH to “lukewarm” temperatures of 30 mK. They’ve precisely measured four OH transition frequencies that will help physicists determine whether the fine structure constant has...

Published: 02/09/2007 - 5:00pm Type of Content: Article-Research Highlight

Scientists anticipate that cold molecules will allow them to explore all kinds of exciting new cold-matter physics. For instance, cold molecules should be able to interact with each other over much longer distances than atoms. They often exhibit an uneven distribution of electric charge called a dipole moment. Unfortunately, the complicated structures of ordinary "warm" molecules means it is...

Published: 09/29/2006 - 6:00pm Type of Content: Article-Research Highlight

Does the electron have an electric dipole moment (eEDM)? If it does, the standard model of elementary particle physics says this dipole moment is many orders of magnitude below what can be measured experimentally. As Fellow John Bohn quips, "It's a darn small one."

On the other hand, various extensions of the standard model predict a much larger eEDM that might be just within reach of a...

Published: 09/29/2006 - 6:00pm Type of Content: Article-Research Highlight

Pancakes of Bose-Einstein condensates (BECs) of polar molecules are repulsive and potentially unstable. However, the physics of these dipolar condensates is delicious, according to research associate Shai Ronen, graduate student Daniele Bortolotti, and Fellow John Bohn. The JILA theorists recently studied BECs with purely dipolar interactions in oblate (pancake) traps.

The researchers...

Published: 02/09/2006 - 5:00pm Type of Content: Article-Research Highlight

When molecules smash into each other, things happen on the quantum level. Electrons get shoved around. They may even jump from one atom to another. Spin directions can change. A chemical reaction may even take place. Since it's not possible to directly observe this kind of electron behavior, scientists want to be able to probe it with novel spectroscopies. Now, thanks to a recent...

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