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  • 02 December, 2020

  • 3 Min Read



What is Quantum Supremacy?

  • It describes the point where quantum computers can do things that classical computers cannot.
  • Superposition and entanglement are what give quantum computers the ability to process so much more information so much faster.

Differences between a standard computer and a quantum computer:

  • A classical computer performs calculations using bits that is 0 (representing off )and 1 (representing on).
  • It uses transistors to process information in the form of sequences of zeros and ones called computer binary language.
  • A quantum computer uses the laws of quantum mechanics.
  • Here, different states can be achieved in particles due to their internal angular momentum called spin.
  • The two states 0 and 1 can be represented in the spin of the particle.
  • Thus, in a classical computer information is expressed through single number either 0 or 1.
  • A quantum computer uses Qubits which is described as a 0 and 1 at the same time giving us more processing power.

Source: TH

  • 10 March, 2020

  • 9 Min Read

Quantum Supremacy

Quantum Supremacy

Part of: GS Prelims and GS-III- S&T

Recently, Google’s quantum computer, named Sycamore, claimed “quantum supremacy”, as it reportedly did the task in 200 seconds that would have apparently taken a supercomputer 10,000 years to complete.

What is “quantum supremacy”?

  • The phrase “quantum supremacy” was coined in 2012 by John Preskill.
  • Quantum supremacy refers to a quantum computer solving a problem that cannot be expected of a classical computer in a normal lifetime.

Quantum Computing vs Traditional Computing

  • Traditional computers work on the basis of the laws of classical physics, specifically by utilizing the flow of electricity. A quantum computer, on the other hand, seeks to exploit the laws that govern the behavior of atoms and subatomic particles.
  • Conventional computers process information in ‘bits’ or 1s and 0s, following classical physics under which our computers can process a ‘1’ or a ‘0’ at a time.
  • Quantum computers compute in ‘qubits’ (or quantum bits). They exploit the properties of quantum mechanics, the science that governs how matter behaves on the atomic scale.
    • In this scheme of things, processors can be a 1 and a 0 simultaneously, a state called quantum superposition.
  • Because of quantum superposition, a quantum computer — if it works to plan — can mimic several classical computers working in parallel.
  • World's most powerful supercomputers today can juggle 148,000 trillion operations in a second and requires about 9000 IBM CPUs connected in a particular combination to achieve this feat.
  • At that tiny scale, many laws of classical physics cease to apply, and the unique laws of quantum physics come into play.
  • Unlike classical physics, in which an object can exist in one place at one time, quantum physics looks at the probabilities of an object being at different points. Existence in multiple states is called superposition, and the relationships among these states is called entanglement.
  • The higher the number of qubits, the higher the amount of information stored in them. Compared to the information stored in the same number of bits, the information in qubits rises exponentially. That is what makes a quantum computer so powerful.
  • Building reliable quantum hardware is challenging because of the difficulty of controlling quantum systems accurately.

What is quantum computing?

Let’s start with the basics.

An ordinary computer chip uses bits. These are like tiny switches, that can either be in the off position – represented by a zero – or in the on position – represented by a one. Every app you use, website you visit and photograph you take is ultimately made up of millions of these bits in some combination of ones and zeroes.

This works great for most things, but it doesn’t reflect the way the universe actually works. In nature, things aren’t just on or off. They’re uncertain. And even our best supercomputers aren’t very good at dealing with uncertainty. That’s a problem.

That's because, over the last century, physicists have discovered when you go down to a really small scale, weird things start to happen. They’ve developed a whole new field of science to try and explain them. It’s called quantum mechanics.

Quantum mechanics is the foundation of physics, which underlies chemistry, which is the foundation of biology. So for scientists to accurately simulate any of those things, they need a better way of making calculations that can handle uncertainty. Enter, quantum computers.

How do quantum computers work?

Instead of bits, quantum computers use qubits. Rather than just being on or off, qubits can also be in what’s called ‘superposition’ – where they’re both on and off at the same time, or somewhere on a spectrum between the two.

Take a coin. If you flip it, it can either be heads or tails. But if you spin it – it’s got a chance of landing on heads, and a chance of landing on tails. Until you measure it, by stopping the coin, it can be either. Superposition is like a spinning coin, and it’s one of the things that makes quantum computers so powerful. A qubit allows for uncertainty.

If you ask a normal computer to figure its way out of a maze, it will try every single branch in turn, ruling them all out individually until it finds the right one. A quantum computer can go down every path of the maze at once. It can hold uncertainty in its head.

It’s a bit like keeping a finger in the pages of a choose your own adventure book. If your character dies, you can immediately choose a different path, instead of having to return to the start of the book.

The other thing that qubits can do is called entanglement. Normally, if you flip two coins, the result of one coin toss has no bearing on the result of the other one. They’re independent. In entanglement, two particles are linked together, even if they’re physically separate. If one comes up heads, the other one will also be heads.

It sounds like magic, and physicists still don’t fully understand how or why it works. But in the realm of quantum computing, it means that you can move information around, even if it contains uncertainty. You can take that spinning coin and use it to perform complex calculations. And if you can string together multiple qubits, you can tackle problems that would take our best computers millions of years to solve.

What can quantum computers do?

Quantum computers aren’t just about doing things faster or more efficiently. They’ll let us do things that we couldn’t even have dreamed of without them. Things that even the best supercomputer just isn’t capable of.

They have the potential to rapidly accelerate the development of artificial intelligence. Google is already using them to improve the software of self-driving cars. They’ll also be vital for modelling chemical reactions.

Right now, supercomputers can only analyse the most basic molecules. But quantum computers operate using the same quantum properties as the molecules they’re trying to simulate. They should have no problem handling even the most complicated reactions.

That could mean more efficient products – from new materials for batteries in electric cars, through to better and cheaper drugs, or vastly improved solar panels. Scientists hope that quantum simulations could even help find a cure for Alzheimer’s.

Quantum computers will find a use anywhere where there’s a large, uncertain complicated system that needs to be simulated. That could be anything from predicting the financial markets, to improving weather forecasts, to modelling the behaviour of individual electrons: using quantum computing to understand quantum physics.

Cryptography will be another key application. Right now, a lot of encryption systems rely on the difficulty of breaking down large numbers into prime numbers. This is called factoring, and for classical computers, it’s slow, expensive and impractical. But quantum computers can do it easily. And that could put our data at risk.

There are rumours that intelligence agencies across the world are already stockpiling vast amounts of encrypted data in the hope that they’ll soon have access to a quantum computer that can crack it.

The only way to fight back is with quantum encryption. This relies on the uncertainty principle – the idea that you can’t measure something without influencing the result. Quantum encryption keys could not be copied or hacked. They would be completely unbreakable.

How will it help us?

  • The speed and capability of classical supercomputers are limited by energy requirements. Along with these they also need more physical space.
  • It can have a major impact through quantum chemistry, which could be important in agriculture and human health.
  • It could help with the development of new pharmaceuticals, new energy sources, new ways to collect solar power, and new materials.
  • Looking for really useful information by processing huge amounts of data quickly is a real-world problem and one that can be tackled faster by quantum computers.
    • For example, if we have a database of a million social media profiles and had to look for a particular individual, a classical computer would have to scan each one of those profiles which would amount to a million steps.
  • In 1996, Lov K. Grover from Bell Labs discovered that a quantum computer would be able to do the same task with one thousand steps instead of a million. That translates into reduced processors and reduced energy.
  • A quantum computer can attack complex problems that are beyond the scope of a classical computer. The basic advantage is speed as it is able to simulate several classical computers working in parallel.
  • 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.

Government's Initiative

  • In 2018, the Department of Science & Technology unveiled a programme called Quantum-Enabled Science & Technology (QuEST) and committed to investing ?80 crore over the next three years to accelerate research.
  • The ostensible plan is to have a quantum computer built in India within the next decade.

Challenges Associated with Quantum Computing

  • The dark side of quantum computing is the disruptive effect that it can have on cryptographic encryption, which secures communications and computers.
  • It might pose a challenge for the government also because if this technology goes into wrong hands, all the government’s official and confidential data will be at a risk of being hacked and misused.

Way Forward

  • 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 will be better to regulate it or define the limits of its legitimate use, nationally and internationally before the problem gets out of hand like nuclear technology.

Source: TH

  • 26 September, 2019

  • 3 Min Read

Quantum Supremacy

GS-III: Quantum Supremacy.


A draft research paper claimed Google researchers have achieved a long-ought-after goal in physics called “quantum supremacy”.

Quantum Supremacy:

  • It refers to a quantum computer solving a problem that cannot be expected of a classical computer in a normal lifetime.
  • This relates to the speed at which a quantum computer performs.
  • The phrase “quantum supremacy” was coined in 2011 by John Preskill, Professor of Theoretical Physics at the California Institute of Technology in a speech.
  • According to reports the quantum processor took 200 seconds to perform a calculation that the world’s fastest supercomputer, Summit, would have taken 10,000 years to accomplish.
  • The draft paper is believed to be an early version of a paper that has been submitted to a scientific journal.

What is quantum computing?

  • Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time.
  • Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

How is Quantum computer different from a traditional computer?

  • What differentiates a quantum computer from a traditional computer is the way the two store information.
  • Quantum computers perform calculations based on the probability of an object’s state before it is measured instead of just 1s or 0s which means they have the potential to process exponentially more data compared to classical computers.
  • Classical computers carry out logical operations using the definite position of a physical state.
  • These are usually binary, meaning its operations are based on one of two positions. A single state – such as on or off, up or down, 1 or 0 is called a bit.
  • In quantum computing, operations instead use the quantum state of an object to produce what’s known as a qubit.
  • These states are the undefined properties of an object before they’ve been detected, such as the spin of an electron or the polarisation of a photon.

Source: Indian Express

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