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[pib] Quantum coin or ‘qubit’ and Entanglement Theory


From UPSC perspective, the following things are important :

Prelims level : Qubit, Quantum Entanglement

Mains level : Quantum Computing and its applications

Researchers from Raman Research Institute (RRI), an autonomous institution under the Dept. of Science & Technology, have devised a new test for fairness of quantum coin or ‘qubit’ using entanglement theory. The Qubit is the basic unit of information in a quantum computer.

Entanglement Theory

  • It is a special type of correlation that exists in the quantum world with no classical counterpart.
  • The researchers from RRI made use of this quantum resource to arrive at a test for fairness of a quantum coin (a qubit).
  • Their strategy, which makes use of entanglement, enables better discrimination between quantum states. Such advantage is valuable in quantum sensors.
  • This work is a significant contribution to the domain of quantum state discrimination, which is an essential aspect of quantum information science.
  • It brings out the crucial role of entanglement in improving our ability to discriminate quantum states.
  • In this work the researchers concretely implemented the theoretical idea on the simulation facility of the IBM quantum computer.

Quantum coins

  • By repeated trials, one can determine the fairness of a classical coin with a confidence which grows with the number of trials.
  • A quantum coin can be in a superposition of heads and tails.
  • Given a string of qubits representing a series of trials, one can measure them individually and determine the state with a certain confidence.
  • The team has shown that there is an improved strategy which measures the qubits after entangling them, which leads to a greater confidence.


  • This is a significant contribution to quantum state discrimination, an essential aspect of quantum information science which is expected to influence quantum sensing.
  • The domain of Quantum Information and Quantum Computing Technology is a growing area of research which is expected to influence Data Processing, which in turn, plays a central role in our lives in this Information Age.
  • For instance, bank transactions, online shopping and so on crucially depend on the efficiency of information transfer.
  • Thus the recent work on quantum state discrimination is expected to be valuable in people’s lives in the current era.
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