A Concise Introduction to Quantum Computing

By Anand G Shankar – Admissions Mentor

A computer is a machine that follows algorithms—step-by-step sets of instructions—to process data and solve problems. The foundation of computing lies in computer theory, especially automata theory and the concept of the Turing machine, which mathematically defines what a computer can and cannot compute. In simple terms, algorithms tell a computer how to solve a task, while computer theory defines the limits and possibilities of what any computer can achieve.

Classical computing uses bits that are either 0 or 1, and it processes information step by step in a deterministic way. For example, if you search for a key in a room with 1,000 drawers, a classical computer would open each drawer one by one until it finds the right one. Quantum computing, on the other hand, uses qubits that can exist in superposition (both 0 and 1 at once) and become entangled, which lets it explore many possibilities simultaneously; in the same key-search problem, a quantum computer could test all 1,000 drawers in parallel and collapse to the correct one when measured. This means classical computers are efficient for everyday tasks like browsing, accounting, or running apps, while quantum computers are designed for highly complex problems such as breaking encryption, simulating molecules for drug discovery, or optimizing huge logistics networks.

Classical computing and quantum computing both rely on semiconductors, but in very different ways. In classical computers, semiconductors (like silicon) are used to make transistors, the tiny on/off switches that represent bits as 0 or 1; billions of these transistors are packed onto chips to perform logic operations and store data. In quantum computers, semiconductors are also crucial, but instead of simple switches, they are engineered into structures like quantum dots or silicon spin qubits, where the quantum properties of electrons (such as spin or energy levels) are harnessed to create qubits that can exist in superposition and entanglement. Thus, while classical computing uses semiconductors to control the flow of electric current in binary states, quantum computing pushes the same materials to their quantum limits, exploiting the behavior of particles at the atomic scale to process information in entirely new ways.

The future possibilities of quantum computing are huge, because it promises to solve problems that classical computers—even supercomputers—cannot handle efficiently. In the coming years, quantum computing could make a big impact in cryptography, where it may break current encryption methods and push the world toward new, quantum-safe security. In medicine and drug discovery, it could simulate molecules at the quantum level to design new treatments much faster. In materials science, it may help create better batteries, superconductors, and clean energy technologies. In finance and logistics, quantum algorithms could optimize portfolios, supply chains, or traffic routes with a scale and speed far beyond today’s systems. It may also accelerate progress in artificial intelligence by boosting machine learning tasks. In the long term, combining quantum and classical computing could lead to entirely new industries and scientific breakthroughs, but large-scale, reliable quantum computers are still years away, and the real challenge is scaling qubits while controlling errors.

Several big companies and startups are leading the race in quantum computing. IBM is well known for its superconducting qubits and already offers access to quantum machines through the cloud. Google made headlines in 2019 by showing quantum supremacy and is working toward larger, error-corrected systems. Microsoft is developing a unique type of qubit called topological qubits and provides access through Azure Quantum. Intel is using its semiconductor expertise to build silicon spin qubits and special chips that control quantum systems. Amazon does not build its own quantum computers but provides cloud access to machines from different providers through AWS Braket. Among startups, D-Wave was the first to sell quantum computers using quantum annealing for optimization problems, IonQ builds stable trapped-ion qubits, Rigetti works with superconducting qubits for hybrid systems, Quantinuum combines Honeywell’s hardware with Cambridge Quantum’s software using trapped ions, and PsiQuantum is trying to build a large quantum computer using light particles (photons). Big semiconductor companies like TSMC and Samsung also play an important role by supporting the manufacturing of quantum chips. Together, these players are shaping the future of quantum computing.

Many leading universities around the world are actively researching quantum computing, each with a different focus. Together, these universities form the backbone of global quantum research, from the physics of qubits to practical applications.

Top Graduate Programs in Quantum Computing

University Country Specialization / Focus Area
MIT USA Superconducting qubits, algorithms, error correction
Harvard University USA Neutral atom qubits, quantum networks
Caltech USA Quantum communication theory, fault tolerance
UC Berkeley USA Trapped-ion qubits, quantum simulation
Yale University USA Pioneering superconducting qubit systems
University of Oxford UK Ion-trap qubits, error correction
University of Cambridge UK Quantum algorithms, optics
ETH Zurich Switzerland Scaling superconducting qubits
TU Delft Netherlands Spin qubits in semiconductors
University of Innsbruck Austria Trapped-ion experiments
University of Waterloo Canada Quantum cryptography, algorithms, hardware
Université de Sherbrooke Canada Quantum devices, materials research
University of Tokyo Japan Superconducting qubits, software
Tsinghua University China Photonic & superconducting qubits
USTC China Photonic quantum computers, quantum communication
University of Sydney Australia Silicon-based qubits, error correction

At Learners Cortex, we help you find the best universities for your master’s program in quantum computing, semiconductors, and supercomputing.