12 August 2017

Nathan Clayburn and Tim Gay in graduation regalia

Dr. Nathan Clayburn has officially completed his Ph.D.! Congratulations!

5 May 2015

Tim Gay shovels dirt on the Newton's Apple Tree

In May 2015, the University of Nebraska–Lincoln planted two Flower of Kent trees on the west side of Jorgensen Hall, home of the Physics & Astronomy Department. Here, Tim is helping to dedicate the tree at a ceeremony held in May 2015. Landscape Services cloned the two trees from the original Flower of Kent tree granted to the university in 1991. Also called Newton’s Apple Tree, UNL's first Flower of Kent tree can be found on the southwest corner of Behlen Observatory. For more information on the Newton's Apple Tree, visit the Physics Department website.

Tim Gay, Jim Williams, and Nate Clayburn

Jim Williams from the University of Western Australia Center for Atomic, Molecular and Surface Physics visits the lab.

12 September 2014

Joan Dreiling and Tim Gay

Recent Ph.D. graduate Joan Dreiling published her first Physical Review Letter in September. It enjoyed wide-spread press, including coverage in:

9 May 2014

Joan Dreiling and Tim Gay in graduation regalia

After so much hard work that paid off, Dr. Joan Dreiling has officially completed her PhD! Munir and Eric have graduated as well! We're so proud of all of them!

18 December 2011

Interior of Professor Gay's lab

The musty smells of Brace Hall have been replaced by the technological scents of Jorgensen! Although Brace has been the home of the Gay lab for many years, we have officially moved into the newly constructed Jorgensen Hall. With a larger space, the lab can be more dynamic than ever! Now that we're all nestled in, you can glance at the new Gay universe.

Check out all of the photos here.

10 August 2010

Our hard-working grad student, Joan Dreiling, gives us a little glimpse into her world, and the exciting project she's been working on, rubidium optical pumping:

Optical Pumping of Mixtures of Rb vapor and N2 Buffer Gas

Link to larger image of apparatus
Fig. 1: Apparatus schematic: (1) linear polarizer; (2) quarter-wave plate; (3) beam sampler; (4) photodiode.

Using the experimental setup shown in Fig. 1, we have studied the optical pumping of mixtures of Rb vapor and N2 buffer gas. As the frequency of the right-hand circularly-polarized (σ+) laser is varied across the D1 absorption profile, the electron spin polarization of the Rb, Pe, is found to take on negative values for small negative values of pump detuning from the absorption profile center (see Fig. 2).

Link to absorption scan
Fig. 2: a) Absorption scan of probe in Rb reference cell. b) Positions of hyperfine transitions, from left to right: 87Rb Fg = 2 → Fe = 1, 87Rb 2 → 2, 85Rb 3 → 2, 85Rb 3 → 3, 85Rb 2 → 2, 85Rb 2 → 3, 87Rb 1 → 1, 87Rb 1 → 2. c) Measured and calculated polarization of Rb vapor as a function of pump laser frequency. Blue data: 10 Torr N2, 4.3 • 1012 cm-3 Rb; solid curve: 10 Torr N2, 99.5% light polarization; dashed curve: 10 Torr N2, 99.95% light polarization. Green data: 1.0 Torr N2 and 8.8 • 1012 cm-3 Rb; curve: 1.0 Torr N2 and 99.5% light polarization. Red data: 0.1 Torr N2, 8.4 • 1012 cm-3 Rb density; curve: 0.1 Torr, 99.5% light polarization.

The spin reversal phenomenon is due to the underlying hyperfine structure of the optically-pumped Rb vapor. This can be understood by considering the Zeeman structure of 85Rb (Fig. 3). When F is less than I+J, the expectation value of Pe for a given eigenstate of the hyperfine Hamiltonian is proportional to -mF. Thus, for 85Rb, if one could selectively populate the 2S1/2 F = 2 state with mF > 0, the polarization of the hyperfine-averaged J-states of the atom would exhibit Pe less than 0. To achieve this by pumping the F = 3 --> F = (2,3) transition, however, requires a non-σ+ component of the pump laser polarization that can drive vertical or left-going absorptions in order to eliminate population of the F = 3, mF = +3 dark state.

Link to larger Zeeman level diagram
Fig. 3: Zeeman level diagram of 85Rb.

We have modeled these effects with rate equations for the individual F, mF ground- and excited-state sublevels for 85Rb and 87Rb. The predictions of the model are depicted as the solid-line curves in Fig. 2c with the fit parameters of laser power 100 mW and the fraction of left-hand circularly-polarized (σ -) light is 0.5%. The model gives reasonable agreement with the data. The dashed-line curve shows the results for 10 Torr with the fraction of σ - light equal to 0.05%. As the data sets were taken on different days, the waveplate may have been set slightly differently for the 10 Torr data set or experienced a small rotation around the vertical axis, which would yield different polarizations at the respective optimal settings.

~Joan Dreiling, Jorgensen Laboratory of Physics

9 August 2010

Did you notice the date? 8, 9, 10! :D
Updates: The Graduates of the Gay Group page is fully updated, so you can see where all those who worked with Dr. Gay ended up. Soon to come will be a page about Joan's interesting project working with rubidium optical pumping. Of course, that's when she's not also working on her other project with chiral (non-imposable mirror-image) molecues: here's a description and visual of that.
Real News: Jimmy's last day at the lab is tomorrow! :( Check out his completed work.

8 February 2010

Here, Joan is pushing a boy on a hovercraft at the Big Red Road Show at the Omaha Qwest Center, reaching out to youth to show how much fun physics can be.

4 October 2005

Office layout
The office was so distraught that Jon left that it rearranged itself.

Updates: Check out the updates in the Inmates section. Plus stay tuned for a list of all the undergraduates of the group and where they are today, just in case you were beginning to abandon all hope.

Real news: We have been joined by Dr. Vola Andrianarijaona. Dr. A is originally from Madagascar, although he comes here by way of Paris, Belgium, and Germany (not necessarily in that order). Stay tuned for his CV, which will be online any day now. Also, we have a new undergrad: Jeff Thomas.

9 May 2005

Jon has gone through and removed every one of his pictures from the website. I'm going to allow this, because a) he'll be leaving soon anyway b) I can't really do anything about it c) he explains that he's afraid of teenage stalkers, government conspiracies, and UFOs. For a more in-depth explanation of Jon's views on photographs and life in general, he refers you to this helpful, illuminating website.
Real News: Umm...happy summer? Jon and Nick graduated, but they're still with us for the time being.

28 March 2005

Professor Gay showing his tour to group of undergraduates

Updates: Welcome to our newest group member Josh Machacek!
Real News: A little while ago (ok, maybe like a month ago) we got a visit from the "women in science" folks. They toured our labs while we scouted for future victims - er, employees.

7 February 2005

Updates: Powerpoints about Jack and Amanda's projects have been put up. Check out the Projects page. We also have a group picture and a picture of our newest member, Xumin.
Real News: ....


Rocker Tommy Lee stopped by the University of Nebraska–Lincoln to film his reality TV Show. He also enlisted Dr. Gay's invaluable help as an advisor. They got on famously.

Professor Gay and Tommy Lee

As far as updates, the Graduates page has been updated, so you can now see where most of the graduates work.

Dr. Gay has published his new book. Go to "The Gay Group Stoops to Popularizing Science" section for more.

Adam Green's thesis work has recently been published in Physics Review Letters. Check the Recent Publications section for the citation and PDF copy.

Justin Zohner has been awarded his Master's, and now has a job in San Antonio. He just goes to show that students can get cool jobs working with secretive high-energy lasers.


Renovations to Brace Labs have begun, and will likely last the summer. A new entrance and more lab space will be added to the building. Unfortunatley, construction also means that my nerves will be tested... darn pile driving...

Link to larger FFT
An FFT of the noise created in the grad offices thanks to the incessant pile driving.
Link to larger image of waves
The vibrations as seen in JB's coffee cup. Note how the shape of the cup creates distinct wave patterns, much like electrons in a quantum corral.