Syllabus: Science and Technology

• Quantum computing has gained global momentum with recent breakthroughs from Google, IBM, and China’s Jiuzhang, each demonstrating systems exceeding 100 qubits. Unlike classical computing, which uses bits that exist in binary states (0 or 1), quantum computing is based on the principles of quantum mechanics and uses qubits, which can exist in a superposition of states. This means a qubit can represent both 0 and 1 simultaneously, exponentially increasing computing potential. The concept was first proposed by Richard Feynman in 1981, envisioning machines capable of simulating quantum systems.
• The fundamental principles enabling quantum computing include superposition, entanglement, and quantum logic gates. Superposition allows qubits to hold multiple states simultaneously, such that a 100-qubit system can theoretically process 2¹⁰⁰ (~10³⁰) possible states. Entanglement enables qubits to be interlinked in such a way that the state of one qubit directly affects the state of another, regardless of distance—a phenomenon Einstein described as “spooky action at a distance.” Quantum gates manipulate these qubits to perform calculations within quantum circuits.
• Quantum computing holds transformative potential across sectors. In drug discovery and material science, it can simulate atomic and molecular interactions with unprecedented accuracy, as seen in collaborations like Pfizer and IBM. In logistics and optimization, it solves complex problems involving supply chains, traffic systems, and investment portfolios. In cybersecurity, quantum computing introduces quantum key distribution (QKD) for theoretically unbreakable encryption, while also threatening current encryption methods via Shor’s Algorithm. Additionally, quantum sensing applications extend to mineral detection, gravitational field mapping, and medical imaging.

• Significant progress has already been made. In 2019, Google’s Sycamore quantum processor achieved quantum supremacy by completing a task in 200 seconds that would take classical supercomputers approximately 10,000 years. IBM has developed quantum systems with over 100 qubits and aims to scale up to 1,000 qubits. China’s Jiuzhang system has achieved quantum advantage using photonic qubits. Startups such as IonQ and PsiQuantum are pioneering scalable quantum hardware using ion-trap and photonic technologies.
• However, the road to practical quantum computing is fraught with challenges. Decoherence remains a major issue, as qubits are highly unstable and collapse within fractions of a second due to environmental noise. Quantum error correction is another hurdle, requiring hundreds of physical qubits to create a single reliable logical qubit. Current systems with 100–200 physical qubits yield only around five usable logical qubits. Moreover, quantum infrastructure demands ultra-cold environments, precision control systems, and significant financial investment.
• Globally, nations are in a competitive race to lead in quantum technologies. China has invested approximately $15 billion, developing a national quantum network. The United States has committed over $4 billion, with companies like Google, IBM, and Microsoft leading private sector innovation. The European Union runs a €1 billion Quantum Flagship program, while the UK, Japan, and Canada are focusing on quantum-safe encryption and hybrid quantum-classical systems.
• India launched its National Quantum Mission in 2020 with a ₹8,000 crore outlay, placing it among the world’s top five quantum investors. Institutions such as the IITs, IISc, and TIFR are currently working on early-stage 5–10 qubit systems, with the goal of developing 50–100 qubit machines by 2030. Key focus areas include post-quantum cryptography, quantum sensors, and secure communication infrastructure.
• Looking ahead, fault-tolerant quantum computers with millions of qubits are expected to emerge by the 2040s. These systems are poised to complement classical computing in domains such as quantum simulations, decryption, and large-scale optimization. The global push now emphasizes developing quantum-safe digital infrastructure, fostering international R&D collaboration, and strengthening domestic capabilities.
• In conclusion, quantum computing marks a revolutionary shift with the power to reshape modern science, defence strategies, economic systems, and digital governance. India’s early strategic commitment, coupled with sustained funding and research, positions it as an emerging quantum power ready to lead in the transition from classical bits to quantum qubits.