What is quantum computing?

Quantum computing is an advanced field of computer science that uses quantum mechanics to solve problems beyond the reach of traditional computers. Unlike classical computers, which process information sequentially using bits (0s and 1s), quantum computers use qubits that can exist in multiple states simultaneously. This allows them to tackle complex problems exponentially faster. Though still in development, quantum computing has the potential to solve challenges that would take traditional supercomputers thousands of years in just minutes.

How do quantum computers work?

Quantum computers differ from classical computers by using qubits instead of bits. While classical bits represent either a 0 or a 1, qubits can represent both simultaneously, enabling quantum computers to process vast amounts of information in parallel. This parallelism allows them to perform complex calculations much faster than traditional systems.

What are Qubits?

Qubits are the fundamental units of quantum information, created by manipulating quantum particles like photons, electrons, trapped ions, and atoms. These particles must be kept at extremely low temperatures to minimise errors caused by environmental noise and maintain their quantum state. The unique properties of qubits enable quantum computers to handle complex tasks that classical computers cannot efficiently solve.

Types of Qubits

• Superconducting qubits – Fast and precise, using superconducting materials at low temperatures.
• Trapped ion qubits – Highly stable, with long coherence times.
• Quantum dots – Tiny semiconductors that hold single electrons, ideal for scalability.
• Photons – Used for quantum communication and cryptography.
• Neutral atoms – Laser-controlled and suited for scaling operations.

Key principles of quantum computing

A quantum computer operates based on quantum principles, which include superposition, entanglement, and decoherence:

Superposition

Qubits can exist in multiple states at once, enabling quantum computers to process millions of operations simultaneously.

Entanglement

When qubits are entangled, knowing one’s state instantly reveals the other's, even at a distance. This enhances computing power and speed.

Decoherence

Qubits lose their quantum state due to environmental factors, posing a challenge in quantum computing. Engineers work to minimise this effect.

What are the components of a quantum computer?

Quantum Hardware:

• Quantum data plane: Contains physical qubits and structures necessary for quantum computation.
• Control and measurement plane: Converts digital signals into analog signals to operate and measure qubit states.
• Control processor & host processor: The control processor runs quantum algorithms, while the host processor manages communication between quantum and classical systems.

Quantum Software:

• Uses quantum circuits to execute specialised algorithms tailored for quantum systems.
• Developers use dedicated quantum programming languages like Q# and tools like IBM’s Qiskit for building quantum applications.

Difference between quantum and classical computing

Classical computing forms the foundation of modern digital devices, using bits (0 or 1) to process data sequentially. This logical and step-by-step approach makes it efficient for everyday applications but limits its ability to handle highly complex problems.

Quantum computing, by contrast, operates using qubits that can represent both 0 and 1 simultaneously (superposition). This parallel processing capability allows quantum computers to handle large-scale problems that are beyond the capabilities of classical machines. While still in early development, hybrid quantum-classical systems are being explored to combine the reliability of classical computing with the efficiency of quantum systems.

How do companies use quantum computing?

Quantum computing has the potential to transform industries by solving complex problems beyond the capabilities of traditional computers. From improving machine learning and optimising operations to revolutionising scientific simulations, quantum technology is opening new frontiers in efficiency, accuracy, and innovation. Here are some key areas where quantum computing is making an impact.

• Machine Learning (ML): Improves data analysis for enhanced predictions, optimises algorithms in chemistry, and assists in simulating molecular structures for drug discovery. Financial institutions use quantum computing for market forecasting and fraud detection.
• Optimisation: Enhances supply chain logistics, production workflows, and resource allocation, reducing operational costs and cycle times. Financial services use quantum systems to optimise loan portfolios and minimise risk.
• Simulation: Enables highly accurate simulations of complex molecules for pharmaceutical research and materials science, surpassing the capabilities of classical supercomputers. Specialised software like QUBEC is used to automate chemistry simulations.