Phonons and Quantum Computers UPSC NOTE

 

What are Quantum computers?

• Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement.

• Devices that perform quantum computations are known as quantum computers.

• Quantum computing is an area of computing based on the principles of quantum theory, which explains the behaviour of energy and material on the atomic and subatomic levels.

• Information storage and manipulation are based on Quantum Bit or “qubit”.

• It is possible to be in more than one state at a time.

• In quantum computers, data processing is done in the Quantum Processing Unit or QPU, which consists of several interconnected qubits.

• Quantum computers will allow much larger calculations.

What are qubits?

• In quantum computing the information is encoded in qubits.

• A qubit (or quantum bit) is the quantum mechanical analogue of a classical bit. 

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• A qubit is a two-level quantum system where the two basis qubit states are usually written as ∣0⟩ and ∣1⟩. 

• A qubit can be in state∣0⟩, ∣1⟩ or (unlike a classical bit) in a linear combination of both states. The name of this phenomenon is superposition. 

• A qubit can be a particle — like an electron; a collection of particles; or a quantum system engineered to behave like a particle.

• Other forms of quantum computing use other units of information. 

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• 
  For example, linear optical quantum computing (LOQC) uses photons, the particles of light, as qubits. 

• LOQC offers to use optical equipment — like mirrors, lenses, splitters, waveplates — with photons to process information.

What are phonons?

• Phonons are packets of vibrational energy.

• According to a paper published in Science, we can build a quantum computer whose information unit is, colloquially speaking, sound.

• Acoustic beam-splitters needed to manipulate phonons.

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The findings of the study

• The researchers developed an acoustic beam-splitter.

• It was placed in the middle of a two-mm-long channel of lithium niobate. 

• Each end of the channel had a superconducting qubit — a qubit whose circuit components were superconducting — that could both emit and detect individual phonons. 

• The whole setup was maintained at an ultra-low temperature. 

• If these phonons were converted to sound, their frequency would be too high for humans to hear.