Last Updated on December 7, 2025 by Dr. Sushanta Barman
Quantum computing is a new way of doing computation. It uses the rules of quantum mechanics to process information. Classical computers work with bits that are either 0 or 1. Quantum computers use qubits, which can be 0, 1, or both at the same time. This special property allows them to try many possibilities at once. Because of this, quantum computers can solve some problems much faster than classical computers. They may become a major technology for future computing and cybersecurity.
Classical Bits vs Quantum Qubits
A bit is like a tiny switch. It can be ON (1) or OFF (0).
A qubit is different. It uses the rules of quantum mechanics. A qubit can be 0, 1, or both at the same time. This is called superposition. Because of this, quantum computers can try many answers at once. This gives them a huge speed advantage for some problems.
Qubits can be made using different physical systems, such as:
These advanced technologies are the heart of quantum technology, helping build future quantum computers and quantum networks.
How Quantum Computers Work
Quantum computers use quantum gates to control and change qubits. These gates follow the rules of quantum mechanics, so they do much more than simple YES-NO logic. They allow the qubits to explore many possibilities at the same time and use interference to increase the chance of getting correct results. This makes certain tasks faster and can also reduce energy use. At the end of the calculation, the qubits are measured, and each one becomes either 0 or 1. The final answer is classical, but the powerful computation happens during the quantum evolution before measurement.
Role of Entanglement
Quantum computers get much of their power from a special effect called entanglement. When qubits are entangled, they become strongly connected. Changing one qubit instantly affects the other qubit, even if they are far apart. This is something that classical computers cannot do.
Entanglement helps quantum computers handle a huge amount of information at the same time. A classical bit can only be one value: 0 or 1. A qubit can be 0, 1, or both at once. So, one qubit can store 2 states at the same time. Ten classical bits store only one combination at a time. But ten qubits can store 2¹⁰ = 1024 states at once. With 50 qubits, a quantum computer can store more than one quadrillion states at the same time. This massive power allows quantum computers to solve very hard problems in chemistry, cryptography, and artificial intelligence. These are tasks that even the fastest supercomputers find hard to solve.
What Can Quantum Computers Do?
Quantum computers are still developing, but they already show great potential in many areas.
They can help improve cryptography by breaking current encryption methods and creating quantum-safe security. In chemistry and materials science, they can help design new molecules and advanced superconductors. They can also boost artificial intelligence by speeding up optimization and pattern recognition. In finance, they may improve risk analysis and portfolio planning. For logistics, they can find the best routes and schedules faster. They can even support climate and energy research by helping design better solar cells and clean-energy technologies like fusion. These real-world applications show why quantum computing is expected to become an important technology for the future.
Challenges of Quantum Technology
Quantum computers are extremely delicate:
- Qubits easily interact with the environment
- Noise leads to data errors (decoherence)
- Cooling close to absolute zero is needed for stability
- Scaling qubits while maintaining accuracy is difficult
Current systems are called NISQ devices (Noisy Intermediate-Scale Quantum), meaning we can run only limited quantum algorithms today.
Research efforts by companies like Google, IBM, Microsoft, and national quantum missions worldwide are pushing rapid progress.
Summary
Quantum computing is a new type of computing. It uses qubits instead of bits. Qubits can be 0, 1, or both at the same time. This helps quantum computers check many possibilities at once. Because of this, they can solve some very hard problems much faster than classical computers.
Quantum computers may help in cryptography, chemistry, artificial intelligence, finance, and clean energy. But the technology is still developing. Qubits are very sensitive and can lose information easily. Today’s quantum computers are still limited in what they can do. Even so, scientists and companies are working to make them better. In the future, quantum computing may become very important for many areas of science and technology.
References
- Sushanta Barman, “Types of Qubits in Quantum Computing”, MatterWaveX.Com, August 23, (2024).
- James Dargan, “What Is NISQ Quantum Computing?”, TheQuantumInsider.Com, September 24, (2025).
I am a Fellow of Academic and Research Excellence (FARE) in the Department of Physics at IIT Kanpur. My work focuses on ion-beam optics and matter-wave phenomena. I am also interested in emerging matter-wave technologies.
