Which one of the following is the context in which the term "qubit" is mentioned?
Answer & explanation
Answer: (b) Quantum Computing
A qubit is a quantum bit, the basic unit of information in a quantum computer. An ordinary bit is either 0 or 1, but a qubit can be 0, 1 or a mix of the two at the same time (a superposition).
- ✓ (b) Quantum computers use qubits in place of the classical bits of a normal computer. Qubits can also be entangled with one another, which gives quantum machines their extra power. India's National Quantum Mission aims at quantum computers with 50-1000 physical qubits.
- ✗ (a) Cloud services supply storage and computing over the internet; they run on ordinary bits and bytes, not qubits.
- ✗ (c) Visible light communication (Li-Fi) sends ordinary digital data as flickers of light, so it has nothing to do with qubits.
- ✗ (d) Wireless communication technologies such as Wi-Fi and mobile networks carry classical bits by radio waves.
Remember · Qubit = quantum bit, the unit of a quantum computer. It can be 0, 1 or a superposition of both.
Sources
- NIST, Quantum Computing Explained (Internet Archive copy) ↗ “instead of regular classical bits, quantum computers use quantum bits, or qubits”
- PIB, Cabinet approves National Quantum Mission (Internet Archive copy) ↗ “The new mission targets developing intermediate scale quantum computers with 50-1000 physical qubits in 8 years in various platforms like superconducting and photonic technology.”
Question and answer: UPSC's official GS Paper I (2022, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·