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Science & TechFree till Sep 9

Quantum Technologies: Communication, Computing, and Sensing

July 19, 2026

TOPIC CLASSIFICATION

Subject: Science & Tech | Topic: Emerging Technologies Sub-topic: Quantum Computing, Quantum Communication (QKD), Quantum Sensing, National Quantum Mission Prelims Focus: Qubits vs bits, quantum supremacy, QKD, National Quantum Mission (NQM) targets, MeitY vs DST roles Mains Focus: Applications in cryptography, defence, healthcare; India's preparedness; global race (US, China, EU); ethical/safety concerns

EXAMINER REASONING

Quantum technologies are a frontier area with transformative potential in computing, communication, and sensing. UPSC Prelims tests basic concepts (qubit, superposition, entanglement) and India's National Quantum Mission targets. Mains questions focus on the strategic implications (quantum-safe cryptography), economic impact, and India's position in the global quantum race.

Core Concept

Quantum technologies exploit quantum mechanical phenomena (superposition, entanglement, tunnelling) to perform tasks beyond classical capabilities.

Three Pillars of Quantum Technologies

PillarDescriptionApplications
Quantum ComputingUses qubits (0, 1, or both simultaneously) — superposition for parallel computationDrug discovery, cryptography, optimisation, AI/ML
Quantum CommunicationQuantum Key Distribution (QKD) — theoretically unbreakable encryptionSecure communication (defence, banking)
Quantum SensingExploits quantum sensitivity for ultra-precise measurementGravimetry, navigation, medical imaging, underground mapping

National Quantum Mission (NQM) — India

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AstroSat and India's Space Observatories

AspectDetail
LaunchApril 2023 (Union Cabinet)
Nodal MinistryMinistry of Science & Technology (DST)
Total outlay₹6,003 crore (2023–2031)
ObjectivesBuild quantum computing, communication, and sensing capabilities
Targets50–100 qubit quantum computer by 2028; 1,000 km QKD link by 2027; 3–4 theme-based hubs
Execution4 Thematic Hubs (IITs, IISc, DRDO, ISRO) coordinated by DST
Technology Readiness LevelCurrently 2–4; target TRL 6–7 by 2030

Key Facts

  • Global quantum investment: ~$40 billion (China $15bn, US $8bn, EU $7bn, India $0.7bn).
  • India's quantum maturity: Position ~20th globally; late mover but fast catching up.
  • First QKD demonstration in India: IIT Delhi (2021) — 100 km fibre link.
  • Quantum computers built in India: 1–2 qubit systems (IISc, TIFR); 8-qubit superconducting (IIT Roorkee, 2023).
  • Quantum key distribution (QKD): ISRO demonstrated free-space QKD (satellite-to-ground) in 2023.
  • Quantum supremacy: Google (2019) — 53-qubit Sycamore; China (2020) — 66-qubit Zuchongzhi 2; India yet to reach.
  • Post-quantum cryptography: NIST (2024) standardised 3 algorithms — India needs to migrate before quantum threat arrives.

PYQ Table

YearQuestionMarks
2023"Quantum technologies are poised to revolutionise computing, communication, and sensing." Discuss India's preparedness.15
2022What is meant by 'quantum supremacy'? (Prelims)2
2021"Quantum Key Distribution offers unbreakable encryption." Examine its potential and challenges.12
2020Which of the following is a property of quantum bits? (Prelims)2

Statement Elimination Guide

  1. "A qubit can be only 0 or 1 like a classical bit." → False. A qubit can be 0, 1, or a superposition of both simultaneously.
  2. "Quantum Key Distribution is currently deployed for all internet communication." → False. It is still limited to experimental/specialised networks due to cost and distance constraints.
  3. "Quantum computers will replace classical computers entirely." → False. Quantum excels at specific problems (cryptography, optimisation) but not general purpose computing.
  4. "India launched the National Quantum Mission in 2023." → True. Approved by Cabinet in April 2023 with ₹6,003 crore outlay.

Current Affairs Hook

  • 2025: NQM thematic hubs operationalised; 8-qubit quantum processor demonstrated.
  • 2024: ISRO-DRDO joint project on satellite-based QKD (quantum communication satellite planned).
  • 2023: National Quantum Mission approved; MeitY QKD testbed (Delhi-NCR ring) inaugurated.
  • 2022: IIT Madras start-up QNu Labs launches commercial QKD solution.
  • 2021: India joins Quantum International Network (led by EU, US).
  • 2020: C-DAC, Pune — quantum computing simulation centre established.
  • 2019: Google claims quantum supremacy — India accelerates research funding.

Interlinkages

  • Cryptography: Quantum computers can break RSA/Diffie-Hellman encryption (Shor's algorithm) — post-quantum cryptography needed.
  • Defence: Quantum sensing for submarines (navigation without GPS), secure military comms.
  • Healthcare: Drug simulation (molecular interactions) — faster protein folding, drug discovery.
  • Banking & Finance: Quantum-safe encryption for digital payments, CBDC (Digital Rupee).
  • Space: Quantum communication for deep space missions; ISRO QKD for satellite secure control.
  • AI/ML: Quantum ML — exponential speedup for training complex models.
  • Climate: Quantum simulation for battery chemistry, solar cell efficiency, fusion energy.
  • Supply Chain: Optimisation of logistics (quantum annealing by D-Wave).

Common Mistakes

  • Thinking quantum computers are just faster classical computers — different paradigm (parallelism through superposition).
  • Believing QKD is already commercially mainstream — mostly experimental, high cost, distance sensitive.
  • Confusing quantum supremacy (solving a problem a classical computer can't) with full-scale general quantum computing.
  • Assuming India is a leader — China, US, EU are far ahead in qubit count and investment.
  • Missing the difference between quantum computing (hardware) and post-quantum cryptography (software/algorithm migration).

Revision Snapshot

TechnologyStage in IndiaGlobal Leaders
Quantum Computing1–8 qubits (lab)Google (53), China (66), IBM (127)
Quantum Communication (QKD)100 km fibre, demo free-spaceChina (Micius satellite, 4,600 km)
Quantum SensingResearch stageEU (gravimeter), US (military)
National MissionNQM (2023) ₹6,003 crUS ($8bn), China ($15bn)

Source Notes

  • DST – National Quantum Mission Document (2023)
  • MeitY – Quantum Technologies and Applications (2024)
  • NIST – Post-Quantum Cryptography Standardisation (2024)
  • DST – India Quantum Technology Review (2025)
  • PIB – NQM Launch, Cabinet Decision (April 2023)
  • Isro – Free-Space QKD Experiment Results (2023)
  • Nature India – Quantum Technology in India (2024)