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Konrad Lehnert


Lehnert spent a couple of years with his family in Brussels, Belgium, during a second extended business assignment. However, his parents had grown frustrated with the language confusion that resulted from the relocation back to the states from Colombia, so they sent their boys to the English-speaking International School of Brussels rather than to a local school where classes were conducted in French.

Lehnert’s father, an engineer by training, sparked his young teenage son’s interest in science by bringing home popular science books, including John Gribbin’s In Search of Schrödinger's Cat: Quantum Physics and Reality, which Lehnert remembers reading along with Timewarps and Spacewarps. The latter books introduced Lehnert to some of Einstein’s exotic thinking about the nature of the world.

By the time he was ready for college, Lehnert had become more practically minded. He knew he was good at math, so he thought he’d like to be an engineer. He was really excited after visiting Harvey Mudd College in Claremont, California, because everyone he met, including the juniors and seniors, was really excited about science and engineering. Plus there were all kinds of nerdy people at Mudd. A self-described “garden-variety nerd” who wasn’t very athletic and loved science fiction books, Lehnert thought he’d feel right at home there.

He started college as an engineering major with the goal of becoming an electrical engineer. Engineering itself (but not the course work) was easy and fun, and the idea of electrical engineering seemed terribly modern and futuristic. However, after his sophomore year, he switched his major to physics because he was much more excited about taking physics classes than engineering classes.

When it was time for a senior project, instead of doing laboratory research in physics, Lehnert opted for an engineering project. He worked for Lockheed-Martin on modifying military aircraft to jam broadcasts. The goal was to be able to continue to broadcast while listening to everybody else’s broadcasts that were being jammed. Lehnert admits he didn’t make a lot of progress on the project, but it spurred an interest microwave and rf technologies that continues to this day.

Even though he was still straddling the fields of engineering and physics during this project, he found Johnson noise far more interesting than most electrical engineers did. Johnson noise is present in every resistor, but to know the power present in the noisy fluctuations, all one needs to know is the temperature. That Johnson noise excited Lehnert was a pretty good indication that he’d be better cast as a physicist than as an engineer. However, it would take him a little more time to figure this out.

Lehnert graduated with honors from Harvey Mudd in 1993, still imagining that he wanted to be an electrical engineer. So, he spent a year working as an analog and rf designer for a cell phone company (Pacific Communications Sciences Incorporated) in San Diego, California. Most days, he sat at a large computer terminal and drew symbolic representations of electric circuits. He made circuits that really worked in the microwave cell-phone frequency range. It was fun for a little while, but he just couldn’t see doing it for 30 years. After a year on the job, Lehnert went to graduate school in physics at the University of California at Santa Barbara (UCSB) in 1994.

At the time, the UCSB physics program was well positioned to go from a kind of sleepy place to being a very good place in a short amount of time, which was a stroke of good luck for Lehnert. He worked with Professor S. James Allen on the nonequilibrium dynamics in superconductor-semiconductor-superconductor junctions. The project moved slowly, but it finally succeeded after Lehnert had the good idea of introducing microwave technology into the experiment he was doing. His graduate research also led to the realization that he loved exploring the underlying physics of electrical systems. He earned his Ph.D. in physics in 1999 and headed east to Yale.

Lehnert did postdoctoral research with Robert Schoelkopf, a new professor in Yale’s Department of Applied Physics. It took the group about 18 months to build a whole lot of complicated lab equipment and get it working. There were few results yet, however. Fortunately the next year was extraordinarily productive. Lehnert worked with his advisor on building superconducting electrical circuits. They figured that if they learned to wire these circuits and keep them cold enough to maintain their quantum mechanical properties, the circuits might be useful for building a quantum computer. After two years, the two came up with some of the newest and most exciting results in the field— just as Lehnert needed to start looking for a job.

Lehnert’s job search was fairly traditional. He applied to multiple positions advertised in Physics Today, including one from JILA. He was intrigued by JILA because it wasn’t quite a government lab, and it wasn’t exactly a university. It seemed like a relatively great place to work that had managed to incorporate some of the best aspects of both its parent institutions. So, despite garnering multiple nice offers, he found JILA’s the most appealing.

Lehnert became a NIST Associate Fellow of JILA in December of 2002 and was promoted to Fellow in 2007. His favorite part of being at JILA is his collaboration with CU Associate Fellow Cindy Regal’s group. During her training, Regal had spent time in Lehnert’s lab as a postdoc. Together, they started a project that has evolved into a collaborative effort to create a coherent, efficient, and bidirectional conversion link between microwave and optical light. A proof of principle experiment of the new converter was successfully carried out in 2013. The experiment has demonstrated how scientifically productive a good working collaboration can be.

Lehnert is a big fan of collaboration as a strategy for fostering innovation in science.  For instance, he’s part of a new collaborative search for the axion, a hypothetical subatomic particle that scientists hypothesize may constitute dark matter. Lehnert is contributing technology developed in his lab for virtually noiseless amplifiers to the collaboration, which also includes researchers from Yale, the University of California at Berkeley, and the Lawrence-Livermore National Laboratory. The new experiment uses a very cold metal box, or cavity, to look for microwave photons with a particular set of properties. Such photons would only exist inside the cavity if axions were present. Lehnert’s role in the experiment is the precision measurement of microwave photons in the cavity, something he does exceptionally well.

Lehnert likes to wander into creative places in the borders between scientific disciplines. He’s open to unanticipated events guiding his research in new directions. For instance, when he was asked to join the new axion experiment, he jumped onboard enthusiastically. Dark matter has always been a profound unknown in science, and thus an extremely attractive research focus.

Lehnert was recently married to Kate Houck, whose background is project management for start-ups in Boulder. The couple enjoys living in Boulder and exploring the nearby Rocky Mountains.

In 2007, Lehnert was a finalist for the Service to America award. He was a Kavli Fellow in 2010 and 2011. He is a Fellow of the American Physical Society.