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Quantum Supremacy

  Jun 12, 2020

Quantum Supremacy

What is quantum supremacy?

John Preskill, a theoretical physicist coined the term "quantum supremacy" in 2012 by John Preskill to describe the point at which quantum computers can perform tasks that classical computers simply can't.

Why is it in news?

Scientists and engineers from Google announced that their machine was able to finish a job in just 200 seconds—and that the world's most powerful supercomputers would need 10,000 years to accomplish the same task. The task involved executing a randomly chosen sequence of instructions

What are quantum computers and how do they operate?

The language that classical computers speak is all about manipulating strings of zeros and ones, but the language of quantum physics is quite different. Instead of using ‘bits’ like computers of today do, quantum systems would use ‘quantum bits’ or ‘qubits’.

Two concepts help capture the quantum computers: super-imposition and entanglement.

Schrödinger's Cat is often used to frame a basic concept of quantum theory to explain the peculiar, but important, concept of superposition where something can exist in multiple states at once.

For Schrodinger's cat- the simultaneous states were dead and alive.

Superposition is what makes quantum computing so potentially powerful.

Standard computer processors rely on packets or bits of information, each one representing a single yes or no answer- 0 or 1.

Quantum processors are different. They don't work in the realm of yes or no, but in the world of yes and no. This twin-state of quantum information is known as a qubit.

How does the power of quantum computers increase?

To harness their power, we have to link multiple qubits together, a process called entanglement. With each additional qubit added, the computation power of the processor is effectively doubled. This means that more powerful quantum computers - ones that will be useful for complex problem solving, like working out how proteins fold or modelling physical processes inside complex atoms - will need numerous qubits. 

What are the practical uses?

It does not have any particular practical uses. But shows the future promise of quantum computing. It is compared to the first successful flight by the Wright brothers. The first plane flew only for 12 seconds, and so there is no practical application of that. But it showed the possibility that a plane could fly.

Scientists see in quantum chemistry a big impact, which could be important in

Some scientists believe it is the possible solution to some of the most complex problems, from global warming and hunger to epidemics.

Its future is bright as universe fundamentally works in a quantum way, so we will be able to understand nature better. 

Any one example with details?

Take fertilizers—the Haber process produces 2% of carbon [emissions] in the world. In nature the same process gets done more efficiently. (The Haber-Bosch process, which makes ammonia for fertilizer by combining nitrogen from the air with hydrogen from natural gas and steam, produces an estimated 1.44% of global carbon dioxide emissions and over 1% of total greenhouse gas emissions.)

Is the claim to “quantum supremacy” challenged?

Computer scientists at IBM have countered that their most powerful supercomputer, called Summit, could complete the same task in 2.5 days rather than 10,000 years. But that is much more than 200 seconds. 

What about India?

Department of Science & Technology has set up a programme called Quantum-Enabled Science & Technology (QuEST). As a part of the programme, it will invest a sum of Rs 80 crore in a span of three years to facilitate research in this field. DST held the first meeting for its QuEST programme at International Institute of Information Technology (IIIT)-Hyderabad earlier in 2019.

The first phase of the project, centred on building infrastructure and acquiring human resources will be over in three years. It would see researchers develop basic physical and computation structures such as logic gates, light sources, sensors, imaging devices, clocks, and more, all in quantum states. The focus would be on quantum metrology (improved precision in measurements) and sensors.

In the 2nd phase, the Indian Space Research Organisation (ISRO), Defence Research and Development Organisation (DRDO), and Department of Atomic Energy (DAE) are expected to jointly pool in a sum of Rs 300 crores to push QuEST to Phase 2, that would ensure that India's quantum computing programme matches international standards.