Stephen Eckel ‘12 PhD, a Research Scientist at the National Institute of Standards and Technology (NIST), was awarded a Presidential Early Career Award for Scientists and Engineers (PECASE) for 2025. Dr. Eckel received his Ph.D. from Yale in 2012, where his thesis work focused on two different precision measurement searches for the electron’s electric dipole moment. His dissertation was titled, “A Search for the Electron EDM using Europium-Barium Titanates” and his thesis advisor was Steve Lamoreaux, Eugene Higgins Professor of Physics and a member of Yale’s Wright Lab.
Dr. Eckel is an expert in cold atom sensing and precision measurement with over sixty published papers and six patents, his current research focuses on using the immutable properties of atoms and molecules to make calibration-free sensors for both temperature and pressure. In 2016, he started as a permanent research physicist at NIST in the Fundamental Thermodynamics Group developing the cold atom vacuum standard, the only primary standard of vacuum pressure in the ultra-high and extreme-high vacuum regimes. Prior to 2016, he was a National Research Council Postdoctoral Fellow at the Joint Quantum Institute, a collaborative institute between NIST and the University of Maryland, where he was working on inertial sensing using ring-shaped Bose-Einstein condensates.
We asked Dr. Eckel a few questions about his research; see below for the interview.
What kind of research did you do in the department? And where?
As a graduate student, I worked on two experiments: one in the basement of the Sloane Physics Lab and the other in the west wing of the Wright Lab. Both experiments focused on detecting a possible permanent electric dipole moment (EDM) of the electron, the detection of which would require physics beyond the Standard Model. One way to envision an EDM is to imagine that the electron’s charge is distorted from a spherical shape. When I was a graduate student, the limit of the electron’s EDM was 10−27 e cm. That is extremely small: if you were to take the classical charge radius of the electron (about 10−13 cm) and blow the electron up to the size of the earth, the deformation from spherical shape would be on the order of 30 nm. Today, because of heroic experiments, the limit is now almost three orders of magnitude better, at 4 X 10−30 e cm.
My thesis experiment with Steve Lamoreaux was to try to measure the electron EDM with a solid state sample. The idea was to take Eu2+ ions, which are sensitive to the electron EDM, doped into a solid sample and apply an electric field. If the electron has an EDM, the electron spins would tend to align with that field and thus create an associated magnetization that can be detected with superconducting quantum interference device (SQUID) magnetometers. While most experiments looking for EDMs were done in atomic or molecular systems, we chose a solid-state system simply because we could interrogate far more atoms, and therefore, electrons, to participate in the measurement. It was a tough experiment; everything had to be controlled well, from the remnant magnetic field to the tiny electric discharges in the high voltage cables. We did not set a new limit on the electron EDM, but we demonstrated that the technique was at least feasible.
I also had the privilege of working with David DeMille, now at Johns Hopkins University, on his PbO electron EDM experiment. At the time, that experiment had been underway for about a decade at Yale, but had not set a new limit. At the same time, Dave had started a new collaboration with Harvard to build the next-generation molecule-based electron EDM experiment, which would be known as ACME. Around the time I was due to graduate, Dave asked if I would help push the PbO experiment across the finish line: all that was required was to take EDM data. We pushed hard on the experiment, eventually getting good EDM data, but ran into several systematics that prevented us from establishing a new limit on the electron EDM.
What kind of research are you doing now?
Being part of the Fundamental Thermodynamic Metrology group at the National Institute of Standards and Technology (NIST), I focus on using atomic and molecular systems to realize new standards and sensors for quantities like pressure and temperature. I have several projects ongoing, but perhaps the project I am most proud of is the cold atom vacuum standard (CAVS). Since the first cold atoms were trapped in magnetic traps inside vacuum chambers in the 1980s, it was realized that collisions between gas molecules remaining in the vacuum and the cold atoms themselves result in cold atoms being ejected from the trap. This effect is one of the main limitations of the lifetime of cold atom traps. We, along with several other teams around the world, have been trying to turn this problem on its head: use the loss of cold atoms from a trap to measure the pressure of the gas in the vacuum chamber. At NIST, we have tested this idea and found it to be accurate to within a few percent without prior calibration. Put another way, the CAVS represents a new, primary standard of vacuum measurement and can improve measurement of ultra high and extreme high vacuum for the next generation of big science experiments like LIGO and the LHC. As part of the project, we have also prototyped a portable version that can potentially replace ionization gauges. More recently, I have become interested in measuring the temperature of blackbody radiation with atoms and molecules, and one of the projects I am involved in has recently demonstrated a calibration-free Rydberg-atom thermometer.
As a scientist, can you describe what you do on a usual day to conduct your research?
NIST is a wonderful place to be a scientist! While my typical day involves much of what you would expect—mentoring students and postdocs, writing and editing papers, proposing new ideas, and building and fostering collaborations—I also get to go into the laboratory myself almost every day. I appreciate still having that day-to-day contact with the experimental apparatus; it keeps me grounded and continually focused on our end goals. NIST also has some of the best scientists in the world, working in a variety of different areas, so I get to collaborate with fantastic researchers and excellent teams.
How did your time in Yale Physics prepare you for what you are doing now?
Working with Steve Lamoreaux and Dave DeMille taught me many valuable things about achieving excellent precision and accuracy in measurement. (One of the fundamental rules: always try to turn whatever you are trying to measure into a measurement of frequency.) NIST is a place where precision and accuracy are paramount and where uncertainty is something to be most carefully quantified. Working on two electron EDM experiments as a Ph.D. student gave me an excellent foundation for obtaining the best precision and understanding the uncertainties.
What inspires and/or excites you about your research?
I love finding mysteries to solve, and they are always there. As one pushes the next digit in precision, you are bound to find something you did not expect. Roughly 95% of the time, you find something strange about your apparatus: something shifting as it changes temperature or a laser locking servo that has some strange drift. But the other 5 % of the time it is some physics that you did not anticipate or did not fully understand, and those are the most interesting problems to sit down, try to understand, and eventually solve. Then you chase the next digit, and it all goes around again.
Are you involved in any outreach, and if so, what, and why is it important to do outreach as a professional scientist?
I do various outreach activities, but perhaps my favorite is to do public lectures about cold atoms, which typically involves demonstrations with other cold things, like liquid nitrogen. (I should admit at this point that I have mostly borrowed from Bill Phillips’s excellent demonstrations, which I highly recommend.) I find that whether the audience is adults or children, everyone can be inspired to learn more about science and be wowed by some of the amazing things you can do with the very cold.
Established by President Bill Clinton in 1996, the PECASE recognizes scientists and engineers who show exceptional potential for leadership early in their research careers. The award recognizes innovative and far-reaching developments in science and technology, expands awareness of careers in science and engineering, recognizes the scientific missions of participating agencies, enhances connections between research and impacts on society, and highlights the importance of science and technology for our nation’s future.