“It’s a rare opportunity and a very special occasion for a grad student to present a talk at a physics colloquium,” explained Zhang. “I felt super excited. I think people enjoyed the talk and our research.”

CU Boulder Physics professor and JILA and NIST Fellow Jun Ye, a leading figure in quantum physics, hosted Zhang’s presentation. The talk discussed some of the groundbreaking research done by Zhang and other members of Ye’s thorium clock team, which was recently published as .

Zhang’s talk focused on the latest advancements in using lasers to measure and control the behavior of atoms, which is essential for studying critical quantum phenomena. He highlighted a significant breakthrough involving the thorium-229 nucleus, where the team used a highly specialized laser to examine nuclear energy levels with incredible precision for the first time. This measurement was achieved thanks to a cutting-edge tool, a laser frequency comb that works in a very short wavelength of light.

Zhang explained how he and the team precisely measured the thorium nuclear clock transition and connected it to the most accurate atomic clock in the world, which uses the element strontium-87. This connection between nuclear physics and precision timekeeping is not just an impressive scientific accomplishment—it could lead to new ways to test fundamental theories in physics. Additionally, it holds the potential to create extremely reliable timing devices that could be used in various important applications.

“This is just the beginning of this new field,” Zhang added. “There are many things that we can do now. We’re improving our laser to get an even better resolution on this newly found nuclear transition. We are also collaborating with different groups and trying other thorium samples to see how the different material changes the transition. We also closely work with theorists to interpret our data and its fundamental physics implications.”

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Once again, the University of Colorado Department of Physics earned top rankings from the . The rankings were announced in early March 2015. 

CU Boulder's Department of Physics was declared the top school in the nation for Atomic, Molecular and Optical Physics for a second year in a row. This ranking rates our program above M.I.T., Harvard and Stanford Universities. Quantum Physics at CU Boulder was ranked number 8 in the nation and overall, we were ranked in the top 20 schools for our exemplary physics program. 

The report gathered statistical information on more than 1,900 programs nationwide to compile rankings in five of the largest professional graduate school disciplines -- business, law, education, engineering and medicine -- as well as some part-time programs. The rankings are based on expert opinions and statistical indicators that measure the quality of a school's faculty, research and students.

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A JILA team—led by Physics Professor and JILA Fellow Jun Ye—has created the highest standard in timekeeping. The experimental atomic clock (pictured left) has set new standards for both precision and stability.

According to the University press release, "Described in a new paper in Nature*, the JILA strontium lattice clock is about 50 percent more precise than the record holder of the past few years, NIST’s quantum logic clock. Precision refers to how closely the clock approaches the true resonant frequency at which its reference atoms oscillate between two electronic energy levels. The new strontium clock is so precise it would neither gain nor lose one second in about 5 billion years, if it could operate that long. (This time period is longer than the age of the Earth, an estimated 4.5 billion years old.)"

Image Caption: JILA’s experimental atomic clock based on strontium atoms held in a lattice of laser light is the world's most precise and stable atomic clock. This image is a composite of many photos taken with long exposure times and other techniques to make the lasers more visible. (Image credit: Ye group and Brad Baxley/JILA)

Read the press release .

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The University of Colorado Department of Physics has been ranked as the number one school in the nation for atomic, molecular and optical physics, according to . This ties CU Boulder's AMO program with that of MIT for the best graduate school program in the nation. Quantum physics was ranked as fifth, according to the report.

Overall, the Department of Physics is 19^th out of 145 ranked schools.

According to their Web site, U.S. News ranks graduate programs in the sciences according to the results of surveys sent to academics in various scientific fields. Those surveyed were ask to rate the quality of graduate programs of their peers.

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Graduate programs across the University of Colorado system continue to earn national prominence based on the latest annual rankings from U.S. News & World Report. <>

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In a paradox typical of the quantum world, JILA scientists have eliminated collisions between atoms in an atomic clock by packing the atoms closer together. The surprising discovery, described in the Feb. 3 issue of Science Express, can boost the performance of experimental atomic clocks made of thousands or tens of thousands of neutral atoms trapped by intersecting laser beams...Read More in .

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