UPSC Notes

Quantum Computing

PYQs

8

Articles

1

Momentum

21

Phase IFoundation

Background

Overview

Quantum computing represents a paradigm shift in computational power with potential to revolutionize various sectors like defense, healthcare, finance, and scientific research. UPSC expects candidates to understand such disruptive technologies, their underlying principles, applications, challenges, and India's initiatives in the field.

Quantum computing is an emerging field that harnesses the principles of quantum mechanics, such as superposition and entanglement, to perform computations. Unlike classical computers that use bits representing 0 or 1, quantum computers use qubits which can exist in multiple states simultaneously, enabling them to solve complex problems intractable for traditional supercomputers.

Phase IIStatic core

Facts & tables

Key facts

Fundamental Unit

Uses qubits instead of classical bits, leveraging superposition and entanglement.

Potential Applications

Materials simulation, cryptography, logistics optimization, climate modeling, drug discovery.

Major Challenge

Dealing with 'noise and errors' (decoherence) due to qubit sensitivity and environmental interaction.

Error Correction

Techniques are being developed to create 'logical qubits' from multiple physical qubits to reduce error rates.

Reference table

Classical Bits vs. Quantum Qubits

FeatureClassical BitQuantum Qubit
State0 or 1 (at any time)0, 1, or superposition of both
Fundamental UnitBitQubit
Processing PowerSequentialMassively parallel (due to superposition & entanglement)
SensitivityLess sensitiveHighly sensitive (prone to decoherence)

Reference table

Static syllabus anchors

TypeReference
Conceptual areaEmerging Information Technologies
Conceptual areaPhysics & Materials Science

Reference table

Institutions & roles

BodyRole
Google Quantum AIResearches/develops
IBMResearches/develops
Department of Science & Technology (India)Funds/promotes
Phase IIIExam lens

Prelims angle

Overview

Prelims angle: Statement-based questions

Prelims angle: Factual recall

Quick revision

  • Quantum computing leverages quantum mechanics (superposition, entanglement) for computation.
  • Qubits are fundamental units, unlike classical bits.
  • Promises breakthroughs in materials science, cryptography, and AI.
  • Major hurdle: decoherence and error rates in Noisy Intermediate-Scale Quantum (NISQ) devices.
  • Error correction techniques are crucial for building fault-tolerant quantum computers.

High-confidence PYQs

Topic timeline

Emerging Information TechnologiesPhysics & Materials Science

The quantum computing age will only begin when we silence the noise

09 Jul 2026 · Quantum computing uses quantum mechanics principles (superposition, entanglement) with qubits to solve complex problems beyond classical computers. Key applications are simulation, cryptography, and optimization. Major challenges include decoherence and error correction, which researchers are addressing to achieve fault-tolerant quantum computers.

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Related topics

Practice writing on this topic

UPSC has asked 8 linked questions on Quantum Computing in Mains. Write an answer to one — and get it evaluated.