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The Odyssey from Classical to Quantum

Google's Sycamore machine just made a calculation that may take a supercomputer 10,000 years to complete.
twitter-logoNidhi Singal | Print Edition: December 1, 2019
The Odyssey from Classical to Quantum

Once upon a time, there was Moore's Law, an observation by Intel Co-founder Gordon Moore, who said computing power (or rather, the number of transistors per square inch on integrated circuits) doubled every two years. The law held for decades. But for a while now, we have seen a hectic race to achieve significant breakthroughs in quantum computing. It is quite different from standard computing - an ecosystem that stores information in bits and bytes and uses 0's and 1's, or the classical binary system, to operate. In contrast, data in quantum computing can simultaneously exist in multiple states, and it is stored in quantum bits or qubits where all possibilities exist at the same time. Qubits are programmable, though, and can potentially solve problems at unthinkable speed. Classical computers are nowhere near that capacity and cannot solve problems fast enough for practical use in a world that is becoming increasingly digital.

Understandably, researchers have claimed various achievements in quantum computing in the recent past. Now, tech giant Google says it has used quantum computing to do some calculations which cannot be carried out even by the most powerful supercomputers of our time. The company calls it Quantum Supremacy, a phrase coined in 2012 by John Preskill, a theoretical physicist at Caltech, to describe the moment when quantum computers can do what standard computers cannot.

So, what did Google's 53-qubit quantum machine called Sycamore exactly do? It carried out a complex calculation to figure out the probability distribution of all possible outcomes from a (quantum) random number generator. Sycamore had the answer in 200 seconds, but today's most advanced classical computer, Summit, may take around 10,000 years to finish that calculation.

Is this a demonstration of Quantum Supremacy, the power of a new type of technology over the existing one? There are mixed reactions. IBM thinks the calculation can be squeezed to two days and a half by the supercomputer using a different approach. But Google's Sycamore was 1.5 trillion times faster.

So far, the promise of quantum computing has been largely hypothetical. Even the calculation carried out by Google was largely irrelevant to everyday life and its problems. But experts think such speed and power could, for example, speed up drug development and benefit people. Or it could decode encryption in no time at all. Or do short work of whatever is too huge to calculate or requires processing and analysing a huge amount of data. Google CEO Sundar Pichai told the MIT that the breakthrough was like the 12-second first flight by the Wright brothers and it could take another decade or more to pay off.

"The first plane flew only for 12 seconds, and so, there was no practical application of that. But it showed the possibility that a plane could fly," he said in an interview with MIT. "The real excitement about quantum is that the universe fundamentally works in a quantum way, and you will be able to understand nature better with it. It is early days, but where quantum mechanics shines is the ability to simulate molecules and molecular processes. I think that is where it will be the strongest. Drug discovery is a great example."

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