The quantum mechanical devices that Dirk Englund’s lab develops are a bit like the vacuum tubes used in the first digital electronic computers: they are rather bulky, and each is the product of careful hands-on assembly by Englund’s group members. But these vacuum tubes are special: they hold inside them not classical information, but quantum bits, which portend the birth of a new era in technology. These “quantum vacuum tubes” are the building blocks of quantum information processors, a long-promised type of ultra-powerful computer that Englund and colleagues say is finally coming within reach.
The next chapter in the history of technology is not simply about faster computers, says Englund, a quantum engineer and the Jamieson Career Development Professor in the Department of Electrical Engineering and Computer Science. Quantum information processing encompasses computing, communications, and sensing, and enables activities that aren’t possible with today’s—or even tomorrow’s—digital electronic computers, no matter how powerful they are. Imagine unhackable secret communications, computers that can search vast databases in an instant, and GPS that can position you with millimeter accuracy.
Quantum information processing can improve all manner of sensors. For example, it can enable magnetometers sensitive enough to detect a door opening on the far side of a building. Another sensing technology that Englund is working on, together with neuroscientists Edward Boyden at MIT and Rafael Yuste at Columbia University, could enable real-time movies of synaptic activity in the brain. Englund and colleagues are also working on applying quantum information processing to simulate quantum mechanical systems, a technology that could revolutionize drug discovery and materials research. “That might allow us to discover new materials, not in a trial and error way, like we’ve been doing, but in a systematic way,” says Englund, who is a member of the Research Laboratory of Electronics and Microsystems Technology Laboratories, and director of the Quantum Photonics Lab.
Quantum information can be stored in the smallest constituents of light and matter—the states of photons and atoms. The catch, says Englund, is that these particles are notoriously difficult to control, and even harder to link together—but these are prerequisites for realizing the promise of extraordinarily fast quantum information processing. Englund’s lab works with small pieces of diamond that contain a fluorescent defect made of an embedded nitrogen atom next to a gap in the diamond crystal. These “nitrogen vacancy” centers behave a bit like trapped atoms, whose electrons and nucleus can be used to represent quantum information. “We could potentially very tightly integrate large numbers of quantum memories on chips,” he says. “They would look somewhat similar to today’s semiconductor chips.”
“It’s still very early in the game, and we’re just learning how to build the first ‘vacuum tubes’ and to string a few of them together—but we have a much clearer vision than we did five years ago about how to go about it,” he says. “I would say there is no fundamental roadblock to building a quantum computer. I’m very optimistic that we are actually entering a new era of information processing.”
With his award-winning blend of physics and engineering acumen, Englund is well-positioned to help usher in this new era.