Key Terms & Concepts — UPSC Mains
Quantum Computing
"A computation paradigm that uses quantum mechanical phenomena — superposition and entanglement — to process information in ways that can exponentially outperform classical computers for specific problem types."
Quantum computing is a type of computation that harnesses quantum mechanical phenomena to process information. Unlike classical computers that use bits (0 or 1), quantum computers use quantum bits (qubits) that can exist in a superposition of 0 and 1 simultaneously — enabling a quantum computer to explore many possible solutions in parallel. Entanglement — a quantum phenomenon where two qubits can be correlated such that the state of one instantly influences the other regardless of distance — allows quantum computers to perform certain computations with a degree of parallelism impossible for classical machines. Quantum advantage (or quantum supremacy) refers to the point where a quantum computer can solve a problem that a classical computer cannot solve in any reasonable timeframe. Google claimed quantum supremacy in 2019 when its 53-qubit Sycamore processor performed a specific calculation in 200 seconds that it estimated would take a classical supercomputer 10,000 years — though IBM disputed the claim. Applications where quantum computing offers potential advantage: breaking current RSA encryption (which relies on the difficulty of factoring large numbers — Shor's algorithm can factor these exponentially faster on a quantum computer); drug discovery and materials science (simulating molecular behaviour); financial modelling (portfolio optimisation); logistics (travelling salesman and supply chain optimisation); and accelerating artificial intelligence training. India's National Quantum Mission (NQM): announced in April 2023 with an outlay of Rs 6,003 crore for 2023-2031. Targets: developing intermediate-scale quantum computers with 50-1,000 physical qubits; satellite-based quantum communication over 2,000 km; quantum cryptography for secure communications; and quantum sensing. Four Thematic Hubs (T-Hubs) will be established at premier institutions (IITs, IISc, TIFR). Post-quantum cryptography: NIST (US) finalised post-quantum cryptography standards in 2024 to replace RSA/ECC before quantum computers become capable of breaking them.
Important for UPSC GS3 Science and Technology. National Quantum Mission is a high-relevance recent policy. Prelims: qubit vs bit; NQM outlay (Rs 6,003 crore); target (50-qubit computer by 2028); 4 T-Hubs. Mains: strategic implications of quantum computing (breaking encryption, national security, Quantum Key Distribution for secure communications), and India's technology sovereignty goals.
- 1 Qubit: quantum bit — can be 0 and 1 simultaneously (superposition)
- 2 Entanglement: correlated qubits influence each other instantaneously regardless of distance
- 3 Quantum advantage: exponentially faster than classical computers for specific problems
- 4 Applications: cryptography, drug discovery, materials science, AI, logistics, finance
- 5 Shor's algorithm: can break RSA encryption on a sufficiently large quantum computer
- 6 National Quantum Mission (NQM): Rs 6,003 crore; 2023-2031; target 50-1000 qubit computers
- 7 NQM T-Hubs: 4 Thematic Hubs at IITs/IISc/TIFR
- 8 Post-quantum cryptography: NIST 2024 standards — future-proofing encryption against quantum attacks
India's National Quantum Mission aims to build a 50-qubit quantum computer by 2028 at one of its Thematic Hubs. Achieving this would allow Indian researchers to simulate molecular structures for drug discovery that are currently computationally intractable, giving domestic pharmaceutical companies a significant research advantage.