For 60 years computers have become smaller, faster and cheaper. But engineers are approaching the limits of how small they can make silicon transistors and how quickly they can push electricity through devices to create digital ones and zeros.
That limitation is why Stanford electrical engineering Professor Jelena Vuckovic is looking to quantum computing, which is based on light rather than electricity. Quantum computers work by isolating spinning electrons inside a new type of semiconductor material. When a laser strikes the electron, it reveals which way it is spinning by emitting one or more quanta, or particles, of light. Those spin states replace the ones and zeros of traditional computing.
Vuckovic, who is one of the world's leading researchers in the field, said quantum computing is ideal for studying biological systems, doing cryptography or data mining – in fact, solving any problem with many variables.
"When people talk about finding a needle in a haystack, that's where quantum computing comes in," she said.
Marina Radulaski, a postdoctoral fellow in Vuckovic's lab, said the problem-solving potential of quantum computers stems from the complexity of the laser-electron interactions at the core of the concept.
"With electronics you have zeros and ones," Radulaski said. "But when the laser hits the electron in a quantum system, it creates many possible spin states, and that greater range of possibilities forms the basis for more complex computing."
Harnessing information based on the interactions of light and electrons is easier said than done. Some of the world's leading technology companies are trying to build massive quantum computers that rely on materials super-cooled to near absolute zero, the theoretical temperature at which atoms would cease to move.
In her own studies of nearly 20 years, Vuckovic has focused on one aspect of the challenge: creating new types of quantum computer chips that would become the building blocks of future systems.
"To fully realize the promise of quantum computing we will have to develop technologies that can operate in normal environments," she said. "The materials we are exploring bring us closer toward finding tomorrow's quantum processor."
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