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Friday, July 10, 2020

Quantum Computer: Test done, real-world use a long way away

In classical computing, heat conspires with time to impose constraints on the possible. In the era of vacuum tubes, lengthy computations could not be completed because equipment would burn out.

Written by Pratik Kanjilal | New Delhi | Updated: October 26, 2019 4:06:31 pm
Quantum Computer: Test done, real-world use a long way away In mid-September, a research paper authored by scientists at 14 institutions and labs, led by Google AI Quantum in Mountain View, appeared on a NASA website. (Source: Googleblog)

The government need not agitate itself any more about getting access to secure communications on social media, because the quantum computer, whose arrival has just been claimed, will render cryptographic security redundant.

What’s claimed, and disputed

In mid-September, a research paper authored by scientists at 14 institutions and labs, led by Google AI Quantum in Mountain View, appeared on a NASA website, and enigmatically disappeared, leaving the scientific and mathematical communities restlessly tossing in its wake. Their excitement was not unwarranted, because the paper had claimed quantum supremacy — the development of a quantum machine named Sycamore which can solve problems which classical computers cannot, for practical reasons.

In classical computing, heat conspires with time to impose constraints on the possible. In the era of vacuum tubes, lengthy computations could not be completed because equipment would burn out. Modern semiconductor integrated circuits also generate heat, not enough to burn, but quite enough to slow down. Google claims that Sycamore crunched a problem in about 200 seconds which would have taken a top-flight supercomputer about 10,000 years. The results — in the paper which had vanished enigmatically — formally appeared in Nature on Wednesday, cementing the claim that a threshold in computing, anticipated since Paul Benioff, Richard Feynman and Yuri Manin opened the discussion in the 1980s, has been crossed.

Meanwhile, researchers at IBM have challenged the Sycamore finding, holding that the classical computer lagged by 10,000 years because it was inefficiently configured. Kicking the tyres and cleaning the plugs, they have argued, would close the gap hand over fist. The matter remains in suspense until IBM replicates the benchmark test. According to the method of science, the question remains open until it publishes its own findings.

Multiple states

Ever since Canadian Prime Minister Justin Trudeau expounded quantum computing to a chaffing journalist at the Perimeter Institute of Theoretical Physics, nothing much remains to be explained. Suffice it to say that while classical machines process bits of information represented by the states 0 and 1, representing on and off, quantum machines manipulate qubits or quantum bits. They have two properties which can process data of higher orders of magnitude — superposition and entanglement.

Though the nature of the quantum and gross worlds are fundamentally different, these can be illustrated by the analogy of Schrödinger’s cat, a hapless animal trapped in a box with something potentially lethal, like a canister of toxic gas. In the gross world, we assume that the cat is alive until the gas is released, after which it is dead. But at the quantum level, phenomena collapse into one state only when they are observed. At all other times, they exist in all possible states. The cat is seen to be dead or alive only when the observer opens the box. At all other times, it is both dead and alive, in a state of superposition. Also, if the cat can set off the gas accidentally, its state and that of the canister are inextricably linked.

This is entanglement, which Einstein called “spooky action at a distance”. Two entangled subatomic particles could be light years apart, and yet be linked. Quantum computers use these two properties to achieve speeds and computational spaces that would defeat a classical machine, by encoding data into quantum states and performing quantum operations on it.

Explained: What is quantum supremacy in computing, achieved by Google? Sundar Pichai with one of Google’s Quantum Computers in the Santa Barbara lab, California, US. (Photo via Reuters)

Miles to go

What does the arrival of quantum computing mean for you and me? Not much. Not right away. Because Sycamore only performed a benchmark test which has no real-world use, and Google cannot deploy it to achieve world domination next week. Even if it has demonstrated quantum supremacy, it could take years or decades for the technology to be freely available.

Qubits are stable only at cryogenic temperatures, and only governments and large corporations can hope to keep a quantum computer on the premises. The rest of us would have to depend on cloud computing and software as a service. Not the shiniest rig if you aspire to hack the living daylights out of Gmail, for instance.

But initially, governments and corporations would be the only users of quantum computing, because only they are interested in the questions it answers. The quantum computer was posited by Feynman for modelling quantum systems. Now, it will find use in labs for modelling systems which exist in the real world only under extreme conditions, like in the Large Hadron Collider.

Quantum Computer: Test done, real-world use a long way away A component of Google’s Quantum Computer in the Santa Barbara lab, California, US. (Photo via Reuters)

Labs would be able to produce cutting edge work without having to invest in large-scale infrastructure, and may not have to collaborate across nations and continents. Quantum computers would also be useful for tasks which handle huge amounts of data. Data mining and artificial intelligence would be major beneficiaries, along with sciences which deal in volumes of data, from astronomy to linguistics.

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The dark side

The dark side of quantum computing is the disruptive effect that it will have on cryptographic encryption, which secures communications and computers. Encryption depends on very large prime numbers, which serve as the seeds from which cryptographic keys are generated and exchanged by the parties to a conversation. It works because encryption and decryption are operationally asymmetric. It is easier for a computer to multiply very large prime numbers than it is to factor a product down to its constituent primes. This differential keeps your WhatsApp messages private, but if the odds were evened by exponentially powerful computers, privacy online would be dead.

Technology isn’t always the solution. Often, it creates new problems, and the solution lies in the law. Long after the birth of social media and artificial intelligence, there are now demands to regulate them. It would be prudent to develop a regulatory framework for quantum computing before it becomes widely available. It is a transformative technology whose future uses, across a wide spectrum of sectors from data analysis to geopolitics, cannot be fully anticipated. In that sense, it is rather like nuclear technology, which was regulated by a global regime 23 years after Hiroshima by the Non-Proliferation Treaty. It would be useful to regulate quantum computing now, or at least define the limits of its legitimate use.

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