Laser Science Group

We are making ultra-cold plasma by photo-ionizing laser-cooled calcium atoms in a Magneto-Optical Trap (MOT). The trap size is about 1 mm and it holds about 10 million calcium atoms at a temperature of 0.001 K above absolute zero. The ultracold plasma is formed when we shine in two laser pulses that ionize all of the atoms.

The plasma is "strongly coupled", meaning that the average "nearest-neighbor" Coulomb energy is orders of magnitude larger than the mean thermal energy of particles in the plasma. A strongly coupled plasma behaves in some ways more like a solid than a gas. One of our major research goals is to understand how strong coupling changes basic processes like recombination and collisional ionization.

We use calcium to create this plasma because the energy level scheme in Ca is favorable for laser cooling and trapping. The blue wavelengths for both Ca and Ca+ are easily generated with standard laser technology. So when plasma is created we can measure the ion temperature and plasma density in a straightforward manner.

Our newest two projects include 

• generating a plasma with both Ca and Yb ions at the same time. 
• characterizing kinetic plasma behavior in plasma mixtures with complex interfaces.
• trapping neutral plasmas in a way that has never been done before.

A small dielectric barrier discharge generates a mm-size plasma streamer — a plasma bullet that travels about 1 cm. We're using a highly sensitive optical phase tool to measure the size and shape of the plasma's electron density distribution.

We're thinking about spectroscopy on Ba as a precursor to a table-top ion clock.

We have positions opened for post docs, undergraduate, graduate students in the Physics and Astronomy Department. We are developing lensless or coherent diffraction imaging to study materials dynamics. We use coherent light sources (x-ray, XUV, and optical), Fourier Optics, and computer algorithms to produce nanometer scale images of materials lens-lessly. 

Post doctoral, graduate and undergraduate student position projects available:

1. Imaging atomic strain in structural materials
2. Studying magnetic materials with tabletop extreme ultraviolet sources
3. Single shot imaging of materials in extreme conditions  
4. 3D, lensless nanometer scale x-ray imaging via applied mathematics and data science
5. Development of quantum x-ray imaging

For more information, contact Dr. Sandberg at rsandberg@byu.edu, 801-422-1497 or N261 ESC

We are studying metals at the nanometer scale to understand how and where structural materials fail. Using a lensless x-ray imaging technique known as Bragg coherent diffraction imaging, we are imaging the strain in metal grains under tension, compression, or high heat environments. This technique can currently provide 3D strain imaging at few nanometer resolution. Under support from the United States Department of Energy's Basic Energy Sciences Program, we are pushing this technique towards atomic resolution and in multiple grains.

We use single, ultrafast x-ray pulses from an x-ray free electron laser and synchrotrons to image materials being developed for inertial fusion energy applications, often when they are being shocked with high power laser systems. It is funded by the Department of Energy through SLAC National Accelerator Laboratory.

When high-intensity lasers interact with materials, they rip electrons from atoms and pull them around at nearly the speed of light.  We model electron behavior under these extreme conditions using a variety of techniques.

We are building an experiment to measure the radiation produced by an accelerated electron with a large quantum-mechanical wave packet.  This experiment uses extremely high intensity lasers along with single-photon detectors to study the behavior of matter at the most fundamental level.

We study light at the level where energy is detected as individual photons. Often this is looking at nonlinear Thomson scattering. We also have projects looking at correlated photons produced from downconversion which can be used to measure quantum coherence effects.