Like big bang cosmology and evolutionary biology, quantum mechanics is perhaps one of the most successful and baffling theories in science. The theory that was developed at the start of the 20th century calculates with incredible precision how light and matter behave.
It became the theoretical foundation of much of today’s information technology, as it has for some aspects of chemical processing, molecular biology, and the discovery of new materials.
Yet physicist Richard Feynman’s private joke about the theory still rings true today: if you think you understand quantum mechanics, then you don’t.
“We don’t understand it, but we can tell you how it works,” said mathematician and quantum scientist Michele Mosca. “We know how to use it, and we are building devices that can use it. There is no uncertainty about how it works and how we can use it to do robust cryptography.”
For years, Mosca has been trying to program a new type of supercomputer that uses the principles of quantum theory to increase the computational power beyond what is attainable by a traditional computer.
Large-scale quantum computers are still a dream today, but Mosca predicts that there is a good chance they can become a reality in 15 years. And when the time comes, these supercomputers could work on complex mathematical riddles.
“Applications include the design of new drugs or new materials that can capture energy better or transport energy more efficiently. New materials are ultimately a collection of atoms which behave quantum mechanically. It’s very hard to simulate quantum mechanical systems or chemical reactions at a chemical level with a classic computer,” Mosca said. “Another example is designing buildings better, such as putting in dampers at the right configurations.”
To comprehend why a quantum computer can work wonders while a conventional computer cannot, one has to first make sense of quantum science that underpins quantum computing. The explanation is not that daunting as Canadian Prime Minister Justin Trudeau has glibly summarized it: “A regular computer bit is either a one or a zero. On or off. A quantum state can be much more complex than that.”
Stephen Watt, dean of mathematics at the University of Waterloo in Canada, explained: “Quantum computing is about using atoms to do computing so it’s not just the true or false, but all of the maybes in between are calculated simultaneously.”
Watt used light as an analogy. “You can think of light as waves or tiny particles of light called photons,” he said. “Since light behaves a bit like waves, when beams are near each other, they mix together. We can look at one of the two photons that are near each other, or come from a common origin, to tell the state of the other one – like the positive and negative of an image.”
So the information that quantum computers process – called quantum bit – can be zeros, or ones, or both. A quantum bit can pack more information than a regular bit. And quantum computers can explore all the different configurations at the same time and learn properties that take forever on a conventional computer.
At the University of Waterloo’s Institute for Quantum Computing, which Mosca co-founded, scientists are working on sending information from the ground to a satellite.
Last August, Chinese space scientists launched the world’s first quantum communications satellite into space. The satellite, called Micius, sends encrypted information from space to the ground with a method called quantum key distribution.
The “observer effect” principle in quantum key distribution means that Micius can detect clandestine snooping, knowing instantly if a packet of information has been opened not by the sender and the intended recipient. Micius, in theory, is hackproof.
But with all the excitement around quantum computing, the technology can threaten existing cyber infrastructure. Cyber attackers with access to quantum tools can break current forms of cryptography.
“Cryptography underpins cyber security, which underpins all our cyber technologies. And we are much more dependent on them today than we were 10 years ago,” Mosca said. “So we need to fix the pillars of cyber security before we have quantum computers.”
The article first appeared in the Standard on February 14, 2017.