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Explained: What is Quantum Supremacy, claimed by Google?


From UPSC perspective, the following things are important :

Prelims level : Quantum Supremacy

Mains level : Quantum Computing and its applications

  • Google announced that it has achieved a breakthrough called quantum supremacy in computing.
  • Scientists have developed an experimental processor that took just 200 seconds, to complete a calculation that would have taken a classical computer 10,000 years.

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.

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.

 What makes a quantum computer so powerful?

  • In their research paper published in the journal Nature, scientists have announced that their Sycamore computer has solved a problem that is considered intractable for classical computers.
  • This was achieved by developing architecture of what is known as “qubits”.
  • “Qubits” is short for “quantum bits”, which are to quantum computers what bits are to traditional computers.
  • The more the number of qubits, the higher the amount of information, which increases exponentially compared to the information stored in the same number of bits.

What exactly has Google achieved?

  • From the development of a single superconducting qubit, the researchers proceeded to systems including architecture of 54 qubits with Sycamore.
  • One of these did not perform, the University of California, Santa Barbara said in a statement.
  • This architecture led to the 53 qubits being entangled into a superposition state.
  • Preparing this superposition state was accomplished in a matter of microseconds.
  • The researchers then sampled from this distribution by measuring the qubits a million times in 200 seconds.
  • The equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years, they wrote in their paper.

Why does it matter?

  • First, it is important to know that scientists are still a long way from developing a quantum computer.
  • What they have achieved is the development of an architecture of qubits, and the demonstration of its computing capabilities.
  • In the long term, scientists are always looking to improve on what they have already achieved.
  • If and when created, a quantum computer could revolutionise science research and technological advances.
  • It could boost areas like artificial intelligence, lead to new energy sources and even to new drug therapies.

Issues with QC

  • On the other hand, there may also be issues of national security.
  • They could also override the encryption that protects our computers and the data we use online.
  • Because of that, the governments of the United States and China consider quantum computing a national priority.
  • As some scientists work on quantum computers, others are devising security techniques that could thwart their code-breaking abilities.
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