Harry Jeffrey Kimble, the William L. Valentine Professor of Physics, Emeritus, passed away on September 2, 2024, at the age of 75. A giant in the field of physics, Kimble—who was also known as H.J. Kimble and Jeff Kimble—performed groundbreaking experiments in quantum optics and quantum information science. His achievements include some of the earliest demonstrations of quantum squeezing and quantum teleportation, among many other trailblazing experiments.

Kimble is perhaps best known for his pioneering work in a field known as cavity quantum electrodynamics, or cavity QED, which is the study of single atoms trapped in cavities in which they strongly interact with single photons of light. Kimble’s cavity QED experiments formed the basis of many quantum technologies being developed today. His research also led to experiments that laid the foundations for research into quantum networks—essentially a quantum internet—in which ensembles of atoms are entangled.

“Jeff had a very deep influence on me as a scientist and as a person,” says John Preskill, Caltech’s Richard P. Feynman Professor of Theoretical Physics. “I was a particle physicist originally but became interested in quantum computers around 1994 and 1995 when they were first starting to get attention. If not for Jeff, I wouldn’t have made the pivot that I did from particle physics to quantum information science. He was a very inspiring and daring scientist whom I am grateful for.”

Oskar Painter, Caltech’s John G Braun Professor of Applied Physics and Physics, says Kimble “was an explorer at heart, who deeply loved the challenge of a solo back-packing trip to Patagonia almost as much as he loved uncovering the mysteries of the quantum world. He was the most intense and inspirational person I have ever worked with, and he had a tremendous impact on numerous generations of students like myself who dreamed of one day taming quantum systems and applying them to new ways of communicating and processing information.”

Kimble also helped establish the Institute for Quantum Information and Matter (IQIM) at Caltech, together with Preskill, who is currently the Allen V. C. Davis and Lenabelle Davis Leadership Chair of IQIM. The center’s roots go back to the late 1990s, when Kimble and Preskill received a grant from the Defense Advanced Research Projects Agency (DARPA) to study quantum computing’s potential applications in cryptography. Later, in 2000, they were awarded funding from the National Science Foundation (NSF) for their growing group, which, at that time, was called the Institute for Quantum Information (IQI).

By 2011, advances in quantum computing hardware gave Kimble, Preskill, and other colleagues the impetus to apply for more NSF funding to broaden IQI’s scope to include experimental work. They received that funding and changed the center’s name to the Institute for Quantum Information and Matter, of which Kimble became the inaugural director.

“IQIM would not have happened without Jeff,” Preskill says. “Over the years, we did several research proposals together and those interactions were very exciting and helped to steer us scientifically.”

Read more in the Caltech Media story Caltech Mourns the Passing of Jeff Kimble (1949-2024)