What is quantum computing?

Quantum computing is a nascent technology that exploits the fundamentals of quantum mechanics with the aim of processing exponential quantities of data at exceptionally rapid speeds. We present an overview of the key technologies and concepts involved in developing these complex systems, recognising that they are extremely high-level in nature and potentially difficult to understand. We hope that this at least provides some basic information regarding the subject as it evolves over the remainder of this decade.

Quantum computing, which holds the promise of surpassing the world’s fastest supercomputers, is now at the early stage where prototypes are functioning efficiently; it remains uncertain as to what form these machines will eventually take, for example what technology will predominantly be used to house qubits.

What are qubits?

Quantum computing revolves around ‘qubits’, or quantum bits, which are essentially two-state basic units of quantum information (typically subatomic particles such as electrons or photons). Unlike classical computer units, ‘bits’, which can be in only one of two states at any moment with values of 0 or 1, qubits are capable of superposition, meaning they can be in both states simultaneously. Currently the two main architectures for housing qubits are the superconducting method (nanoscale loops of superconducting wire chilled to near absolute zero temperatures (-273°C)) and ion traps (ions trapped in magnetic fields), but other technologies may emerge.

Market prospects

The global quantum computer race is intensifying, with the number of new prototype technologies increasing exponentially. To date, the United States has led the way but Europe and Asia are seeing significant growth in the number of startups and new projects. Various sources indicate that the quantum computing market size was c $470m in 2021 and is expected to exhibit a CAGR of 30% to 2030, surpassing $1bn by 2026. Other sources predict that it will exceed $125bn by 2030. We expect the hardware segment, in particular, to record appreciable expansion, driven by rising product usage in artificial intelligence (AI) and molecular simulation applications.

While hardware revenues are expected to grow, the number of quantum computers is expected to be limited, although the values will be high. As a pricing example, the European Commission selected a consortium to build a 100-qubit quantum computer by 2025 with an initial budget of €18–20m. Most of the market revenue growth is projected to come from cloud access services to a quantum computer.

Over time quantum computer applications are expected to create most value for markets such as finance, energy, materials, telecoms and healthcare/ pharmaceuticals.

Key concepts

Two key quantum concepts applicable to qubits are explained below:

Superposition: an electron’s spin can either be in alignment with a magnetic field, known as spin-up state (1), or opposite the field, known as spin-down state (0). A pulse of energy generated (usually from a laser beam) can initiate a change in the state of the electron’s spin. Besides being in state 1 or 0, qubits can also represent numerous combinations of 0 and 1 at the same time. The ability to be in multiple states simultaneously is called ‘superposition’. To put qubits into superposition, researchers need to manipulate them using precision lasers or microwaves. Superposition provides the ability to crunch a high number of potential outcomes at the same time. During a single measurement, the number of possibilities is 2ⁿ (n  = number of qubits used); thus a 64-qubit computer has enough memory for over 18 quintillion numbers. This ambiguity (the ability to ‘be’ and ‘not be’ concurrently) is what provides quantum computers with such power.

Entanglement: entanglement is the term used for particles that are entangled pairs of qubits that exist in a state where changing one qubit directly changes the other, which will simultaneously assume the opposite spin direction, enabling operations to occur at lightning speed. Knowing the spin state of the entangled particle (spin-up or spin-down) gives away the spin of the other in the opposite direction. This phenomenon is essential for a quantum algorithm to offer exponential speeds compared to classical computations.

Edison Insight
Quantum computers provide a step change in processing speeds and computing power. While still in the early stages of development, the quantum computing market is expected to grow rapidly to c $5bn by 2030 from c $470m in 2021.