Quantum Computing: Journey from bits to qubits

Syllabus: Science and Technology

Source:  IE

Context: Quantum computing has drawn global attention after Google, IBM, and China’s Jiuzhang showcased systems crossing 100 qubits.

About Quantum Computing: Journey from bits to qubits:

What Is Quantum Computing?

• Quantum computing uses the principles of quantum mechanics—not classical physics—to perform complex computations using qubits (quantum bits).
• Origin: Proposed by Richard Feynman in 1981, it aims to simulate quantum systems using machines that follow quantum rules like superposition and entanglement.

How It Works?

• Superposition: Qubits can represent both 0 and 1 simultaneously, unlike classical bits (0 or 1), enabling massive parallel processing.

E.g. A 100-qubit system can represent 2¹⁰⁰ (~10³⁰) states at once.

• Entanglement: Qubits become interlinked so that the state of one instantly affects another, regardless of distance — a feature Einstein called “spooky action at a distance”.
• Quantum Gates and Circuits: Logical operations are performed using quantum gates that manipulate qubits’ phase and entangled state.

Applications of Quantum Computing:

• Drug Discovery & Material Science: Simulate molecular interactions to design drugs and materials at the atomic level.

E.g. Pfizer and IBM collaborate on quantum simulations for drug development.

• Logistics and Optimization: Solve complex problems in supply chains, traffic control, and portfolio management.
• Cybersecurity: Enables quantum key distribution (QKD) for secure communication and could break existing encryption using Shor’s Algorithm.
• High-Precision Sensing: Used in mineral detection, gravitational field mapping, and medical imaging.

Progress So Far:

• Google’s Sycamore (2019) performed a task in 200 seconds that would take a supercomputer 10,000 years.
• IBM has built systems with over 100 qubits and targets 1,000-qubit machines.
• China’s Jiuzhang achieved quantum advantage using photonic qubits.
• Startups like IonQ, PsiQuantum explore trapped ions and photonic methods for scalability.

Challenges in Implementation:

• Decoherence and Fragility: Qubits collapse quickly under environmental noise—lasting only 10⁻⁴ seconds in some cases.
• Error Correction Overhead: Requires many physical qubits to build one stable logical qubit.
• Scalability: Current machines with 100–200 qubits only deliver 5 reliable logical qubits—not enough for real-world applications.
• Infrastructure Cost: Requires ultra-cold environments, vacuum chambers, and advanced quantum labs.

Global Race in Quantum Computing:

• China: Leads with $15 billion public funding, investing in national quantum networks.
• USA: Spent $4 billion; firms like IBM, Google, Microsoft dominate the private sector.
• EU: Runs a €1 billion “Quantum Flagship” program.
• UK, Japan, Canada: Invested in quantum-safe encryption and hybrid computing.

India’s Status:

• Launched National Quantum Mission (2020) with ₹8,000 crore funding.
• Institutes like IITs, IISc, TIFR run 5–10 qubit systems and goal set for 50–100 qubits by 2030.
• Working on quantum-safe cryptography, sensing systems, and post-quantum communication.
• India is among the top five global investors, alongside China, US, EU, and UK.

Future Outlook:

• Full-scale, fault-tolerant quantum computers with millions of qubits are expected by 2040s.
• Quantum will augment classical computing, solving tasks like quantum simulations, decryption, and complex optimizations.
• Global push is on for quantum-safe systems, cross-border collaborations, and indigenous R&D.

Conclusion:

Quantum computing signifies a paradigm shift that can transform science, defence, and economy. India’s early commitment positions it to become a key quantum power if it sustains investment and research. From bits to qubits, the future belongs to those who decode the quantum universe.

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