Mingyu Fan took a photograph of a single radium ion scattering light as it hovered in free space where it was trapped by electric fields. In the primary picture you can see our vacuum chamber and trapping apparatus. When you look through the window of our vacuum chamber and zoom in to the highlighted yellow region you find floating in empty space (the black rectangle) a radium atom. The camera captures the light scattered by a radium ion over several pixels, resulting in the little blue dot in the center of the image.

Our research both studies and utilizes radium ions and it requires exacting levels of control. We need our ions to stay fixed in space for 10's of hours so that we can both manipulate and detect the radium ion with laser light. For example, while holding the ion with electric fields we apply two lasers at different wavelengths, 468 nm (the blue light in the picture) and 1079 nm (infrared light that is invisible to your eye), to laser-cool the ion. This level of control requires a lot of careful work and creativity, primarily by Mingyu and Craig.

A challenge of portrait photography is getting your subject to stay still under the proper conditions, etc. With the time that has been put into our scientific apparatus it is easy (now!) to have our subject sit still, typically for an entire night of automated measurements, and the only remaining challenge is keeping the camera steady for a long exposure to collect the faint bits of light emitted from a single radium atom.

Unlike most atoms you might be familiar with radium is radioactive. This means you are looking at a picture of a young atom (it has not decayed yet). This particular isotope, radium 226, has a half-life of 1600 years, so it is almost certainly older than you are, but probably younger than The Great Pyramid and definitely a little baby compared to the dinosaurs.

26 Jul 2018 by amj

Mingyu and Craig trapped and, for the first time, laser cooled radium ions! The image shows one of the first trapped and laser cooled radium ions from our lab - yes, that is a picture of a single radium atom. Radium is famously radioactive, but the great scientific value is the high mass of the nucleus and its large octupole deformation. The special nucleus allows us to study nuclear physics as well as particle physics with our trapped radium ions. Because the atom has not been laser cooled there are a lot of basic electronic structure measurements to make. We'll then study the radium nucleus as well as make massive molecular ions with our trapped radium ions for precision measurements. Our ion trap allows us to simultaneously load and trap radium and strontium ions, providing a platform to explore both species and the richness that comes with trapping and laser-cooling two alkaline earth atoms.

Working with a radioactive material in a modest research laboratory requires special techniques and tools. Our effort greatly benefited from much specialized equipment that comes from collaborations with UCLA and UC Berkeley. We are particularly grateful for the time-of-flight mass spectrometer that was designed and developed by Christian Schneider and the Einzel lenses and trap designed by Dave Hucul

Laser cooling of a single trapped ytterbium ion with the doubled light of an optical frequency comb was demonstrated in the Campbell Lab. Phonon lasing of the trapped ion between pairs of comb teeth was studied, and it was found that red comb tooth prevented the blue tooth from driving the ion beyond a certain amplitude. Frequency doubled (or quadrupled) light from freuqency combs is currently the only way to generate light in the deep ultraviolet to address transitions in important species such as He+. Crucially, the Campbell Lab used the doubled comb light to load and crystallize hot ions which opens the door to working with ions such as He+.

15 Aug 2017 by amj

We saw our first signal of trapped strontium ions on August 15th. The trap lifetime was limited by background gas collisions because the plan was to bake after loading our first ions. Post bake we were able to laser cool to generate crystals of trapped ions. The image shows a chain of 17 trapped strontium ions. We are working on our electronics and control to compensate for stray electric fields to reduce excess micromotion so that we can pursue our science goals.

Everyone in the lab contributed to this effort, including significant contributions from the lab's undergrads: Alexander James setup the 405 nm photoionization laser as well as other optics. Sam Dutt made and characterize the neutral strontium oven and Jack Roten meticulously cleaned our vacuum parts.

10 Apr 2017 by amj

UCSB undergraduate Jared Pagett joins the group.

16 Mar 2017 by amj

Ania Jayich and I created the first Math Kangaroo center in Santa Barbara, CA in late 2016. Math Kangaroo is an international math competition that takes place annually on the third Thursday in March. Leading up to this year's exam we hosted 5 practice sessions on Saturday mornings for the eighteen 1st through 5th graders that registered for our Math Kangaroo center. Twelve students from our center took the 2017 Math Kangaroo exam, along with roughly 5 million students worldwide. See me with students on test today with our new Math Kangaroo shirts. We are looking forward to growing the program and hosting more practice sessions soon for Math Kangaroo 2018.

We are excited to have Anna Wang join our research efforts. Anna graduated from UCLA where she developed expertise in AMO physics while working in Wes Campbell's group. After graduation she worked at HRL laboratories on quantum dots for applications in quantum computing.

Cooling on a two-photon transition with an optical frequency comb is published. In Wes Campbell's Lab at UCLA we demonstrated that by driving a two-photon transition the entire power of an optical frequency comb can be utilized to laser cool and trap atoms. We developed the technique (using rubidium) for cooling atoms with deeply bound valence electrons such as hydrogen and carbon for precision measurement and quantum chemistry. Please see our paper


John Barry, the master of laser cooling molecules, wrote a Physics Viewpoint article covering our research.

UCLA newsroom

Phys.org article