A qubit can be made from anything that follows quantum rules and can be controlled precisely. Researchers are still working out which approach will scale best, so several are being developed side by side, much as early computers used valves and relays before transistors won.
The main approaches at a glance
| Type | How qubits are made | Strengths | Challenges | Examples |
|---|---|---|---|---|
| Superconducting | Tiny electrical circuits cooled close to absolute zero | Very fast operations; made with chip-manufacturing techniques | Needs large refrigerators; qubits are relatively short-lived | IBM, Google, Rigetti |
| Trapped ions | Charged atoms held in place by electric fields | Very accurate operations; any qubit can interact with any other | Slower operations; hard to scale to many ions | Quantinuum, IonQ |
| Neutral atoms | Uncharged atoms held by focused lasers (“optical tweezers”) | Large arrays of hundreds to thousands of atoms; flexible layouts | Slower operations; atoms can be lost | QuEra, Pasqal, Atom Computing |
| Photonic | Particles of light travelling through optical circuits | Works with fibre optics; much of the hardware runs near room temperature | Photons are easily lost and hard to make interact | PsiQuantum, Xanadu |
| Silicon spin | Single electrons trapped in silicon chips | Could use existing chip factories; very small | Early stage; sensitive to tiny material defects | Intel, Diraq |
A special case: quantum annealers
Companies such as D-Wave build quantum annealers: machines with thousands of qubits designed for one kind of task, finding low-energy solutions to optimisation problems. They are not general-purpose quantum computers and cannot run algorithms like Shor’s.
On the horizon: topological qubits
Microsoft and others are pursuing topological qubits, which aim to be naturally resistant to errors. This approach is still at an early research stage.
Which one will win?
Nobody knows yet, and there may be no single winner. Different designs may suit different jobs, and future machines may combine them, for example using light to link separate processors.
task_altKey takeaways
- check_circleLeading qubit types: superconducting, trapped ions, neutral atoms, photonic and silicon spin.
- check_circleEach trades off speed, accuracy and ease of scaling differently.
- check_circleQuantum annealers are special-purpose machines, not general quantum computers.