What is a qubit?
Everyone says quantum. Almost nobody says what it means. There is no maths on this page — only the ideas, in plain language, with something to play with.
A bit is a switch. A qubit is a coin in mid-air.
Every device you have ever owned is built from bits. A bit is a switch: off or on, 0 or 1, nothing else. That predictability is what makes computers useful — and it is also their ceiling.
Click it. It is exactly what you set it to, every time.
Spinning, and genuinely undecided. Click to look.
Every result was genuinely unpredictable, yet the totals settle close to an even split. Give up certainty about any single answer and you get something an ordinary switch cannot do. Everything else in quantum computing is built on that trade.
The words you will hear
Every one of these has a plain meaning hiding behind it, and usually a second name people use interchangeably.
- Qubit also called: quantum bit
- The quantum version of a bit. It can hold a mix of 0 and 1 at once, and settles on one of them only when measured.
- Superposition also called: being in both states at once
- Holding several possibilities at the same time. Not "we don't know which" — it genuinely has not settled yet.
- Entanglement also called: spooky action at a distance
- Two qubits sharing one fate. Measure one and the other resolves instantly, however far apart, with nothing passing between them.
- Quantum gate also called: a quantum operation
- An operation that changes a qubit without measuring it. H creates superposition, X flips 0 and 1, Z shifts the phase. Try them above.
- Measurement also called: collapse, observation, readout
- Looking. It forces the qubit to commit to 0 or 1, with odds set by its state, and destroys the superposition in the process.
- Decoherence also called: losing the quantum
- A qubit leaking its state into its surroundings and quietly turning back into an ordinary bit. It is the main reason quantum computers are hard.
Ninety years, in seven steps
Quantum computing is not new. The argument that started it is older than the transistor.
- 1935
Einstein, Podolsky and Rosen publish a paper arguing that quantum mechanics must be incomplete. The disagreement it starts runs for decades.
- 1964
John Bell turns that philosophical argument into something you can actually test in a laboratory.
- 1981–82
Alain Aspect runs those tests with entangled photons. The results side with quantum mechanics, not with Einstein.
- 1994
Peter Shor publishes an algorithm that would let a quantum computer factor large numbers — the problem most modern encryption leans on.
- 1995–96
Shor and Andrew Steane describe the first quantum error-correcting codes, showing fragile qubits could in principle be protected.
- 2019
Google reports a processor finishing a sampling task it argues is infeasible classically. The claim is disputed, but the race becomes public.
- 2022
The Nobel Prize in Physics goes to Aspect, Clauser and Zeilinger for the entanglement experiments. Einstein was wrong, officially.
We are named after the second one.
Straight answer: LiveQbits does not build quantum computers, and neither does anyone else who is being honest about selling one today. Useful quantum hardware is still research.
What we take from it is the way of thinking — hold every possibility open, commit only when you have to. That is how we build software, AI agents and digital products right now, for clients from first prototype to production scale.