Why quantum computers should excite us
If you still dream of working on a computer that is a million times, or much more, faster than the ones you currently use at home or in your office, here’s some news. Your dream became a reality more than 18 months back.
On 4 May 2016, International Business Machines Corp. (IBM) said its scientists had not only built such a computing platform but also made it available on the IBM Cloud so that any person could access it from their desktop or mobile device—but not for Word documents or Excel sheets. The reason: It was a five-quantum bit (qubit) computer.
“When you talk about quantum computers, you cannot think of them in terms of normal computers. The person will have to learn the programming interface QISKit (quantum software development kit), and have some knowledge of the type of algorithms that are appropriate for a quantum computer,” Arvind Krishna, senior vice-president and director of IBM Research, explained in a recent interview to Lounge.
“IBM’s 5-qubit computer on the public cloud can actually simulate simple molecules like hydrogen,” he added. In early 2017, IBM upgraded the quantum machine to 16 qubits, and to 20 quibits in November. “We also announced around the same time that we have a 50-qubit quantum computer that is ready but not fully operational,” Krishna said.
What exactly is a quantum computer? While the computers we use in our homes and offices today process information with bits (ones and zeroes), quantum computers have qubits that can process the ones and zeroes simultaneously due to a property known as superposition.
Two bits in your normal computer can be in four possible states (00, 01, 10, or 11) but they can represent only one of these states at any given time. A quantum computer, on the other hand, allows two qubits to represent the exact same four states at the same time because of superposition. This is akin to four computers running simultaneously. Further, as you add more qubits, the power of your quantum computer grows exponentially.
Quantum computers also take advantage of another property of quantum physics called quantum entanglement. Albert Einstein referred to entanglement, a property which allows quantum particles to connect regardless of their location in the universe, as “spooky action at a distance”. Hence, when you measure a qubit in an entangled system of two qubits, the outcome tells you what you will see when you measure the other qubit. Quantum entanglement allows qubits to communicate with each other even if they are miles (or even millions of miles) apart.
More than 69,000 “distinct users from outside of IBM have, till date, run around two million different experiments” on the IBM quantum computing platform, trying to solve problems, including “search, optimization, chemistry, and early levels of AI (Artificial Intelligence) and ML (Machine Learning)”, Krishna said.
Companies that have officially signed up to leverage IBM’s quantum computing platform include Daimler AG, JPMorgan Chase and Co. and Samsung. “While JPMorgan Chase is working on financial-risk algorithms, Daimler is interested in materials,” Krishna said. He added that the cloud quantum computing platform is being used by developers, researchers “and even some high-school kids in over 40 countries, including India, but we don’t share break-up numbers”.
A 5-qubit quantum computer, according to Krishna, may not solve a problem that is world-changing “but it will help your brains to get used to solving these kinds of problems”. He clarified, though, that quantum computers will not replace normal computers. “You don’t want, for example, your bank balance to be on a quantum computer because you want to know the exact cash balance you have in the bank—not a probability of the amount,” he explained.
According to Krishna, quantum computers are more suited to problems that “are probabilistic, such as molecules or risk or optimization”. For instance, he explains, “If you try to simulate a caffeine molecule on a normal computer, it (the computer) will have to be over one-tenth the volume of this entire planet in size. But you can perform this task on a 160-qubit computer. Therefore, quantum computers can address problems that traditional computers cannot.”
“We (IBM) also care about problems like financial risk but we may need computers that are bigger. Probably 200-400 qubits to be able to solve a problem to figure out the risk in currency or an investment portfolio, or market movements— volatility, etc.,” Krishna added.
Another area where quantum computing could be used, according to Krishna, is in helping to reduce the amount of energy that fertilizers consume. If researchers learn how bacteria fix nitrogen in the soil effortlessly while consuming negligible amounts of energy, the research could help manufacturers save a lot of energy when producing nitrogenous fertilizers. This will help farmers in India, and the world over, reduce fertilizer costs and simultaneously help tackle climate change, according to Krishna.
However, building a universal quantum computer—one which can be programmed to perform any computing task and be exponentially faster than normal computers for applications in science and business—is easier said than done.
To begin with, the “margin of error by quantum computers today, even when dealing with simple materials, is about 50%”, Krishna cautioned. Adding qubits may result in reducing this margin of error, he added. Second, qubits are coherent only for a small amount of time—“about 90 microseconds,” according to Krishna. Coherence is a property that keeps the qubits stable.
Third, it is expensive to build a quantum computer. According to a 26 January 2017 report in the Wired, cybersecurity firm Temporal Defense Systems “bought the D-Wave 2000Q—the firm’s first 2,000 quantum bit (qubit) quantum computer—and although the price it paid has not been revealed, the computer is valued $15 million (around Rs97 crore).”
While he did not reveal figures, Krishna insisted that the price of quantum computers would fall as economies of scale were achieved.
“It is a standard semiconductor process for the electronics. But you need cryogenics (to store the chips at very low temperatures)—you need 15 milliKelvin, which is about 1,000 times colder than outer space. This (supercooling) is the most expensive part but the costs will reduce as we achieve scale,” Krishna said.
Krishna believes a lot of problems that demonstrate the fundamental advantages of quantum will become accessible to people between 50-100 qubits. He concludes: “At 50 qubits (a prototype for now), a quantum computer will be able to solve a useful problem. I think, by 2020, quantum computers will solve problems that will surprise humans.”
■ The idea of a quantum computer was postulated in 1982 by American theoretical physicist Richard Feynman. Today, technology companies such as IBM, Microsoft, Google, D-Wave, Intel, and academic institutions like the Massachusetts Institute of Technology, Princeton University and the University of Waterloo are all working on quantum computer prototypes.
■ China is building a $10 billion (around Rs64,820 crore) research centre for quantum applications. The National Laboratory for Quantum Information Sciences, slated to open in 2020, has two research goals: quantum metrology and building a quantum computer.
■ Last June, a Chinese quantum satellite dispatched transmissions over a distance of 1,200km to help establish “hack-proof” communications between space and the ground.
■ The D-Wave 2000Q system has 2,000 qubits and a powerful new set of processor-level control features. However, critics say D-Wave’s machine isn’t really a quantum computer, mostly because its qubits aren’t built like those in traditional quantum computers.
■ Princeton University researchers built a rice-grain-sized laser powered by single electrons tunnelling through artificial atoms known as quantum dots. It is being touted as a major step towards building quantum-computing systems out of semiconductor materials
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