Campus & Community

The familiar becomes strange: in Charles Marcus’ world, you can be in two places at once

7 min read

Charles Marcus doesn’t believe that he or anyone else lives in the real world. He thinks that everything we see around us, from wood to whales, comes from a more basic place, a bizarre quantum world where things can be in two places at once.

Marcus, among others, is trying to find how the familiar emerges from quantum strangeness.

“This is not philosophical gobbledygook,” he says. “Rather, it’s fundamental to learning about the structure of the universe, and to practical applications such as new types of lasers, transistors, and even totally secure communications.”

Harvard agrees with Marcus. The University recently established a new initiative called the Center for Imaging and Mesoscale Systems (CIMS), wherein the word “mesoscale” can be taken to mean the border between quantum and classical worlds.

“CIMS is the reason I came here from Stanford,” notes the 38-year-old recently tenured professor of physics. “The Center’s goal is to put Harvard on the front rank in this exciting field, and I want to be part of that.”

He will be, says Robert Westervelt, Gordon McKay Professor of Applied Physics who advised Marcus as a doctoral student and postdoc at Harvard. “I am very happy that Charlie is back. He’s a sharp original thinker and a great experimentalist. Charlie can take an intriguing idea that might seem too difficult to test and quickly develop the right experimental approach.”

A blur of possibilities

An experiment done with Westervelt in 1991 revealed part of the subtle difference between the familiar and quantum worlds. The two built electronic devices so small and so cold, they crossed the border into the quantum world. In that world, you cannot pin down the precise position or movement of an object.

To demonstrate, Marcus, a friendly and energetic man, threw a ballpoint pen across his office. “At any point in its path,” he explained,” I can measure where the pen is.” But in the quantum world, a tiny subatomic particle, like an electron, travels many paths simultaneously. When you try to measure where the particle is in the classical way, all but one possible path goes away. In other words, the electron isn’t either here or there, one place or the other, until it’s measured. Before then, it’s just a blur of possibilities.

According to quantum theory, familiar objects arise from the ghostly subatomic world where everyday intuitions don’t hold true. “One of the fundamental mysteries of science deals with how that happens,” Marcus says. That’s one of the mysteries that he and his colleagues at the Center for Imaging and Mesoscale Systems will attempt to solve. Even partial solutions would produce thrilling intellectual gains, along with enormously useful devices like new types of computers with working parts as small as molecules that can compute, communicate, and create and crack codes beyond the reach of today’s machines.

Pizza at home

The Harvard experiment was a turning point in Marcus’ life. “It both caught my imagination and got me on the faculty at Stanford (University),” he notes. That was in 1992. The ebullient physicist eventually gained tenure at Stanford, and in doing so he was able to pay back Westervelt and Harvard for both his quantum and classical insights.

“I sent back gifted students to do graduate work here,” he recalls. “Some of them are still at Harvard, and I enjoy seeing them again.”

Marcus received both his master’s (1987) and doctorate (1990) degrees from Harvard and was irresistibly drawn back to the place. An article in the Crimson declared it was because of the pizza at Pinocchio’s, near Harvard Square. Marcus only partly denies that.

“On a recruiting trip, I was in Pinocchio’s with my wife and son,” he says. “I was thinking how much I felt at home in Cambridge. I had become sort of an East Coast person by then, and everything felt so right here.”

Pinocchio’s has a laminated copy of the Crimson article hanging on a wall. “That ought to be worth a free slice of pizza,” Marcus comments.

A good place to grow up

Marcus grew up in Sonoma, Calif., and earned a bachelor’s degree in physics with honors and departmental distinction at Stanford. He fondly remembers Sonoma as “a good place to grow up.” At the time, his mother was a neurophysiologist working at a nearby hospital, and he spent happy times helping his father tinker with automobiles. Those nudges toward a career in science were reinforced by excellent teachers in both eighth grade and high school.

“I still remember every word I heard in Mr. Knight’s science class in high school,” he says. “By that time I liked physics; it really made sense to me.”

Sonoma remembers Marcus as well. He was class valedictorian at his 1980 graduation and was invited back this year for a 20th anniversary celebration. He couldn’t make it, but he still keeps in touch with high school friends. He met his wife, Claudia Goulette, there.

At Stanford, Marcus wanted to do research, so he walked the walls of the physics building until someone took him in. He worked with physicists John Anderson and Francis Everett on an “excruciatingly accurate” gyroscope meant to test Einstein’s idea that Earth’s gravity produces a curve in the fabric of space. Unfortunately, the National Aeronautics and Space Administration has not yet gotten around to launching the instrument.

Stanford also introduced Marcus to his ideal of a dedicated teacher. “Jeff Dunham gave individual problems to each student according to his interest — astrophysics, particle physics, whatever,” he recalls. “And the problems were too hard to do by yourself, you needed to get into discussions with him or with other students. I still have his notes, and I refer to them for my own graduate course in quantum mechanics.”

Marcus himself gets high marks for teaching. “Charlie is an exceptionally fine teacher who looks at new ways to present concepts and interest his students,” Westervelt comments.

Ultra-small, ultra-cold

In 1984, Marcus came to graduate school at Harvard. Under Westervelt’s tutelage he worked on electronic chips designed to mimic networks of brain cells that make possible sight, thinking, and learning. After earning a Ph.D., Marcus began looking for the best place to do post-doctoral research. He found it in Westervelt’s lab.

His mentor needed someone with experience in building ultra-small electronic devices, devices that when cooled to near minus 460 degrees Fahrenheit would produce quantum effects. Marcus did not have the needed experience because he had spent too much of his graduate time theorizing instead of building devices to test the theories.

“Bob could have gotten an expert in the field, but he showed his faith in me by hiring me instead,” Marcus notes.

“I asked Charlie to stay at Harvard because I knew he had the skills and energy to do a difficult experiment on electrons inside tiny structures and to understand what the results meant,” Westervelt explains.

This work led to the “beautifully successful experiment” that started Marcus down the road he now follows with great enthusiasm and satisfaction.

Outside the window of his office, on the third floor of Jefferson Laboratory, Marcus can see his future. In the now open area between Jefferson and the Science Center will be erected the Center for Imaging and Mesoscale Systems. There, Marcus and his colleagues expect to explore the boundaries that separate the classic and quantum worlds, to manipulate the knowledge they gain into useful products, and to have intellectual fun while they do it.

On the walls by the window hang symbols of the present, pen-and-ink drawings done by his artist wife and photographs of his 15-month-old son, Sam. “We’re very happy here,” Marcus says. “We still have many good friends at Stanford, so we don’t think of our change as leaving there but as coming here.”