Flagg’s Award will support research to measure the spin of a single extra electron trapped in a nanoscale semiconductor crystal called a quantum dot. An electron spin in a quantum dot is a candidate to be a quantum bit, or qubit – the basic unit of a quantum computer. The promise of quantum computing is that it will perform certain calculations orders of magnitude faster than even the most powerful supercomputer that exists today. But getting to that point requires researchers to overcome many challenges, including a major one: how to make and control a qubit. Flagg’s research is directed at developing quantum dots into viable qubits
In order to work as a qubit, the electron spin must be initialized, manipulated, and then measured to obtain useful information, but these three operations have proven difficult to combine.
“The operations require both magnetic fields and light. The problem is that manipulation requires a magnetic field pointing one way, and measurement requires a magnetic field pointing a perpendicular way. You can’t have both at the same time,” Flagg notes. “The key thing is that it’s hard, or impossible in some cases, to do all three operations to the same spin. That is the difficulty this research is trying to address.”
The research project will explore the possibility of measuring electron spin states using the AC Stark effect, a phenomenon associated with laser light. The Stark effect, named for physicist Johannes Stark, who discovered it in 1913, is the shifting and splitting of spectral lines of atoms and molecules due to the presence of an external electric field. Flagg is proposing to read quantum information optically, a process he hopes to accomplish by preparing the spin for measurement by hitting it with a laser beam to reveal the up or down nature of electron spin, without altering that spin. This would allow the three operations of initialization, manipulation, and measurement of an electron to be combined.
The Cottrell Scholar program also aims to foster the educational efforts of recipients. Flagg intends to develop, evaluate, disseminate, and support course packages for upper-division physics topics that integrate active learning techniques developed by the physics education research community.
“A complete and readily available course package would allow instructors – especially new faculty and those teaching a course for the first time – to easily incorporate such techniques when they teach,” he said. He has already developed a course package for Modern Physics that includes flipped classroom design, peer instruction, and learning via problem solving.
The Research Corporation for Scientific Advancement is a private foundation that supports basic research in the physical sciences in the U.S. It was established over one hundred years ago by Frederick Gardner Cottrell. Cottrell, a professor at the University of California, Berkeley, had invented and patented the electrostatic precipitator used to clean particulates from the exhaust of factories and refineries. He used the profits from the sale of precipitators to fund the Research Corporation. Today, outstanding candidates are admitted to the ranks of Cottrell Scholars through a stringent peer-review process based on their innovative research proposals and education programs.