Faces of the Foundation: Jill Foley

Faces of the Foundation
posted: 3/19/2018
listed in Fellows

Jill Foley doesn’t want to take over the world. The president and co-founder of Twinleaf LLC, Jill is justifiably proud of the exquisitely sensitive magnetic sensors her team develops and produces, but, she says, "I don't think you need a highly precise atomic magnetometer, and I'm not here to convince you."

Jill works with the select crowd of physicists and engineers who do need to make measurements on the order of femtoteslas – trillions of times smaller than a fridge magnet’s field. Her clients have specialized applications in government, industry, and academia. They include experimentalists hoping to pick up a hint of physics beyond the standard model – and that’s just the way she likes it. 

In the fall of 1997, Jill had her Hertz interview with Wilson Talley, then the President of the Hertz Foundation, at a Friendly’s restaurant on Rt. 9 in Hadley, Massachusetts. Through an interview touching on the physical principles behind everything from solar power to cooking pasta, Talley encouraged Jill to take her love of physics and problem-solving to perhaps the grandest physics and engineering problem of all – the long-running efforts to build a sustainable fusion reactor. Thus convinced, Jill took her fellowship to Princeton and the Princeton Plasma Physics Laboratory (PPPL).

When she arrived in New Jersey, and began looking for an advisor, Jill gravitated rapidly towards the sort of precision instrumentation that requires delicate physics to build and enables the discovery of even more physical principles. "I love to build stuff, I love to have my hands in it, to make it work," she says.

She would spend her PhD developing tools to probe the magnetic field within fusion reactors; her advisor, Fred Levinton, is the founder and president of Nova Photonics, a company which makes devices precisely for this purpose.

Jill credits the Hertz Fellowship for giving her the freedom to work with Levinton, rather than on another project with a more traditional funding route. And Twinleaf, she says, came directly out of this work. “"I learned from him how it was possible to start a company," she says "there's so much to it you don't see in graduate school."

The Hertz Community has also provided Jill with valuable relationships since her graduation. In 2015, she met Derek Lidow, a Hertz Fellow, author, and visiting professor in entrepreneurship at Princeton, whose books, Startup Leadership and Building on Bedrock she highly recommends. “I appreciate that he understood that for us it’s not just about the money. Money is a tool that we use to build tools and solve problems.”

One of the problems Jill is currently working to solve offers a hint at physics beyond the standard model of quarks, leptons and bosons that currently dominates fundamental physics. For a project called GNOME (Global Network of Optical Magnetometers for Exotic physics), Twinleaf developed highly shielded, highly sensitive magnetometers to take synchronized readings all around the world. The team is searching for transient spin-dependent interactions that might arise, for example, if Earth passes through a compact dark-matter object like an axion star or a Q-ball.

A blip on a single magnetometer could be noise, but a blip on all 14 of them at once could mean that the globe is passing through just such a discontinuity.

“I feel so grateful to be able to support scientists who are doing this really cool stuff by giving them a tool," she says. “We’re serving the human need to understand the world.”