Quantum computing - The next big step?

Last Updated : 28 October 2019, 12:08 IST
Last Updated : 28 October 2019, 12:08 IST
Last Updated : 28 October 2019, 12:08 IST
Last Updated : 28 October 2019, 12:08 IST

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Nobel Laureate Richard Feynman famously said, “If you think you understand quantum mechanics, you don't understand quantum mechanics.” The term quantum has become quite popular with the introduction of the fictional 'quantum realm' in movies from the giant Marvel Cinematic Universe franchise. In the real world, Google recently published a research paper in Nature magazine, where the claimed they had built a quantum computer that achieved 'Quantum Supremacy', and the term was quickly picked up by media outlets and social media to describe what sounded like a world where we would soon have a personal quantum computer at home. But, is this really the case? We break down the terms used and statements made by the parties involved to provide a more cohesive perspective of the recent updates.

What is quantum computing?
Computers since their invention to this date follow the same principle of binary or classical computing. In classical computers today, i.e, machines ranging from a calculator to a supercomputer, information on their silicon semiconductor chips are processed and carried by units called 'bits' that exist in binary states - either a 0 (off) or a 1 (on) at any time.

Quantum computers, however, work in a fundamentally different way by utilizing the physical properties of sub-atomic particles. These particles go by laws and principles that defy the visible world, like superposition (existing in two states simultaneously, made famous by Schrödingers thought experiment).

So a quantum computer does not depend on bits on a silicon chip, instead of relying on sub-atomic 'qubits' in a super-cooled superconducting and isolated environment, that are capable of existing in multiple states at once. Qubits also follow another fundamental property of quantum mechanics, entanglement, that allows for the simultaneous measurement of all the qubits regardless of the distance between them. What difference does all this complicated science make in technology? Read on to find out.

Why is quantum computing important?
Classical computers can emulate quantum computing behaviour up to a certain threshold. Beyond that limit, a qubit's capability to superimpose and entangle allows for quantum computers to be, in theory, exponentially more powerful than the largest, most efficient supercomputer. As the number of qubits linked together in a computer increases, it becomes even more capable of processing massive amounts of data simultaneously. In fact, an increase of a single qubit could possibly double the time taken by a classical computer to emulate its processing.

This makes quantum computing potentially hyper-efficient in particular scenarios. In his recently published blog post, Google's CEO Sundar Pichai said that the quantum computing can "accelerate solutions for some of the world's most pressing problems, from climate change to disease" and claimed that as nature intrinsically functions with quantum mechanics, quantum computing gives the best chance to simulate the natural world at a molecular level. If this can be achieved, it opens up a whole new avenue of being able to design better power cells and batteries, improve on or find an alternative to the currently used Haber-Bosch process (used to manufacture fertilizers), and manufacture new medicines and cures.

In the long run, quantum computers might also be able to easily crack complex encryption algorithms, and solve high performance quantum physics calculations that pose quite a challenge to classical computers, with some scientists theorizing a 'quantum advantage' wherein real-world problems that can't be touched by conventional computing would be solvable with its quantum counterpart. Do keep in mind that what is being referred to as classical computers in this context, are incredibly powerful supercomputers.

What has Google managed to achieve in the field of quantum computing?
Google is one among a few companies that have been working to make quantum computing a feasible reality. To that extent, the Silicon Valley tech giant designed the Sycamore processor- a processor with 54 qubits arranged in a two-dimensional grid layer. The computer, maintained in a vacuum at temperatures near absolute zero to ensure accuracy, was then made to run an experiment wherein it had to describe the likelihood of different outcomes from a quantum version of a random number generator. This is a staggeringly complicated operation to carry out, but Sycamore took effectively 3 minutes and 20 seconds to solve it using 53 of its 54 qubits, whereas Google claims that “a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task.”

The company then went on to state that their device had reached 'Quantum Supremacy', a term originally used by John Preskill (Professor of Theoretical Physics at the California Institute of Technology) to describe the point where classical computers could no longer realistically or effectively emulate the tasks carried out by a quantum computer. As until now, researchers have only been able to emulate quantum processing up to 40 qubits on a classical computer, this statement does seem to hold true. Sundar Pichai likened the achievement to the first flight of the Wright Brothers - a breakthrough in the field as a whole although the experiment itself held little practical purpose apart from resulting in the first certified random number generator, useful in encryption software and population sample studies. However, IBM disagrees with Google's conclusion.

Why IBM is just not interested to buy Google's claim of 'Quantum Supremacy'?
The supercomputer Google used to compare simulated performance with their quantum computer, was rival company IBM's Summit computer. IBM is also working on furthering quantum computing capabilities, even designing a computer that could be accessed via the Cloud by anyone requesting it. In their research blog, however, the company argued that Google's simulation of the task was faulty and that ideally, the worst-case estimate for the time taken by the supercomputer to solve the problem would be two and a half days, and with additional refinements, the time could be reduced, while the accuracy would be much higher than the quantum version.

They further argued that quantum supremacy had not been met by the Sycamore processor, as a classical computer could still realistically replicate the performance. IBM even provided an explanation as to why there were such massive discrepancies between Google's estimate and their own, stating that Google had only considered the RAM storage capacity needed by the Summit, but had not taken into account further hard disk space, various software assets, and a massive knowledge base of algorithms accumulated over decades.

IBM concluded that Google's claim was also misleading because 'quantum computers will never reign “supreme” over classical computers, but will rather work in concert with them since each has its unique strengths.'

If IBM's claims are to be believed, then Google's feat would be reduced to demonstrating the massive intrinsic advantage that quantum holds over classical computing, which still remains as a very significant landmark considering the fact that Sycamore completed the task well over a thousand times faster than Summit potentially can.

So what now?
With the Sycamore processor, Google has staked a claim to be the frontrunner in the industry, with IBM, IonQ and other companies similarly progressing. However, for quantum supremacy to turn into practicality, it's major shortcomings need to be addressed. Qubits have such fragile quantum states, that each lasts only for a fraction of a second, and any minuscule 'noise' in the environment like temperature changes, vibrations or electromagnetic fields, can disrupt both the qubit and their relations with the other qubits. This causes errors in calculations, and degrades the reliability of the machine, limiting the operations that they can run. Quantum computers thus, have to be stored in extremely controlled environments with temperatures lower than outer space, completely removing any semblance of ease-of-use for it at present.

The Google experiment was specifically designed for a quantum computer to run and was therefore successful, but more complicated algorithms like Shor's algorithm for arbitrarily large numbers, are still years away from being implemented. But this quantum gap does not mean the field remains to be rudimentary in the world today. Research into quantum computing has spiked, with Google's announcement only increasing it for the foreseeable future. Startups like Rigetti have grown into large companies offering cloud-based quantum computer services. Even China, in addition to it's already burgeoning technology cold war with the US, has considerably invested in quantum computing. The world may not be ready to effectively take full advantage of quantum computing yet, but it is steadily pushing towards it.

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Published 28 October 2019, 10:50 IST

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