Understand the concept of quantum computing for UPSC CSE/IAS prelims and mains

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Username akashaky
on 24/10/2019

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The Present Context

  • Google has officially claimed that they have achieved quantum supremacy.
  • Google claims that they are able to build a quantum computer that is able to solve complicated in just 200 seconds that take the world's fastest supercomputer 10000 years.
  • This computer is a 54 qubit( qubit is explained later in this article) computer.
  • However, this claim of google is challenged by IBM.

Quantum Computer: A quantum computer is a computation system that makes direct use of quantum-mechanical phenomena.

Classical computing and classical bits

  • Classical bits: The basic component of a classical computer is the bit(a single binary variable values of 0 and 1)
  • A classical computer uses binary bits(0s and 1s) for the process of computing.
  • The classical computer can exist in only one stage at a given instance. However, they have 2^n combinations of states.
  • The stage of a classical computer is described by some long combinations of 0s and 1s. Ex: 000011110000101010........
  • For example, a 32-bit computer has 2^32 stages but can exist in only one stage a given instance.

Origin of Qubit and Schrodinger's Cat thought experiment

  • Schondrigner imagined a box inside which there is a cat and there is also a flask of poison.
  • The flask of poison has to be opened by an automatic trigger that has been placed inside the box.
  • When the flask will open the poison is going to kill the cat.
  • But for an external observer, there is no way to know when the trigger is opening the flask and going to kill the cat.
  • The only way to know the condition of the cat is to open the box, so for the external observer, the cat is appeared to be both dead and alive at the same time.
  • This originates the concept of quantum superposition and qubit which can store more than one stage at an instance

Quantum Computing and qubits

  • Science students may know that a part of Quantum Physics deals with multiple behaviors of the electron, and photons at a given time.
  • Quantum computers use Qubits for the process of computing. Here Qu in Qubits stands for Quantum.
  • The main difference between bit and qubit is that the qubit allows quantum computers to occupy 2^n(n is the number of qubits) stages at a given instance which makes the quantum computing exponentially faster than classical computing, while the bit allows a classical computer to occupy only one stage at a given instance.
  • The property of quantum computers to occupy multiple stages at any instance of time is known as Quantum Superposition.

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