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Quantum Computing
5.1 Classical vs. Quantum Computing (PYQ 2023 — Q18)
| Parameter | Classical Computing | Quantum Computing |
|---|---|---|
| Basic Unit | Bit (0 or 1) | Qubit (superposition of 0 and 1) |
| Processing | Sequential/parallel logical operations | Quantum parallelism — explores all states simultaneously |
| Key Principles | Boolean logic, transistors | Superposition, Entanglement, Interference |
| Error Rate | Very low with mature error correction | Currently high (NISQ era — noisy intermediate-scale quantum) |
| Applications | General purpose computation | Cryptography, optimization, drug discovery, ML acceleration |
| India's Status | India has supercomputers (PARAM series) | NQM targets 50–1,000 qubit computers by 2031 |
Key Quantum Concepts for RPSC
- Superposition: A qubit can be in state 0 and 1 simultaneously until measured (unlike classical bit which is fixed at 0 or 1).
- Entanglement: Two qubits can be "entangled" — measuring one instantly determines the state of the other, regardless of distance. Einstein called this "spooky action at a distance."
- Quantum Decoherence: The main engineering challenge — qubits lose their quantum state due to interaction with environment; requires ultra-cold temperatures (near absolute zero, ~15 millikelvin).
5.2 National Quantum Mission (NQM)
The National Quantum Mission was approved by the Cabinet Committee on Economic Affairs (CCEA) on 19 April 2023, with a budget of Rs 6,003 crore over 8 years (2023–2031). It is a Mission-Mode project under the Department of Science and Technology (DST).
Four Strategic Thematic Hubs (T-Hubs)
- Quantum Computing — hosted at IISc Bangalore; target: develop superconducting, photonic, and trapped-ion based quantum computers
- Quantum Communication — hosted at IIT Madras; target: secure quantum key distribution (QKD) over 2,000 km fiber and free-space communication
- Quantum Sensing & Metrology — hosted at IIT Bombay; target: atomic clocks with 10⁻¹⁸ precision, gravity sensors, quantum imaging
- Quantum Materials & Devices — hosted at TIFR Mumbai; target: topological qubits, quantum memory, quantum materials synthesis
India's Targets under NQM
- Quantum computers: 50–1,000 physical qubits by 2031
- Secure quantum satellite communication between ground stations
- Quantum cryptography networks for financial and defence applications
- High-sensitivity quantum gravimeters and magnetometers
Global Context
The US has invested $1.2 billion in its National Quantum Initiative (2018). China has achieved 100+ qubit quantum advantage experiments. India's NQM positions it in the second tier of quantum-capable nations.
India's Early Quantum Steps
- C-DoT (Centre for Development of Telematics) demonstrated India's first quantum communication link (100 km fiber) in 2022.
- ISRO has worked on quantum key distribution for satellite communication.
- Quantum Computing India startup ecosystem: QNu Labs (Bengaluru) sells commercial QKD systems; BosonQ Psi focuses on quantum simulation for aerospace.