AI EncyclopediaFirst steps2/5
First steps in quantum computing
A guide for complete beginners
Quantum technology uses the physics of the world smaller than atoms (quantum mechanics) for computing and communication.
Why everyone is talking about it
Ordinary computers calculate with bits, which are either 0 or 1. Quantum computers use qubits, which can be 0 and 1 layered together. They are expected to solve certain problems far faster than today's computers, such as molecule calculations for finding new drugs or materials.
Qubits still make mistakes easily, so this is at the stage of experiments and early use. That is why today's news is less about how many qubits were built and more about how well errors are fixed. There is also worry that quantum computers could break today's encryption, so the switch to new encryption is happening at the same time.
The big picture
- Build qubitsQubits are made from things like superconducting circuits, ions held in an electric field, or particles of light.
- Block disturbanceHeat and electromagnetic noise break their state, so they are cooled to extreme cold or held in a vacuum to protect them.
- Compute with gatesQuantum gates change the state of the qubits and create superposition and entanglement to do the calculation.
- Fix errorsSeveral qubits are grouped so that wrong ones can be found and fixed. A qubit made reliable this way is called a logical qubit.
- Measure the answerAt the end, measuring gives a definite 0 or 1. The program runs many times and the results are combined into an answer.
One quantum computation, shortened to five steps.
Six ideas to know
Read them in this order and the news gets much easier. Each one opens its encyclopedia entry.
- Quantum computerA new kind of computer that uses the physics of the very small (quantum mechanics) to calculate.
- QubitThe smallest unit of information in a quantum computer. It can be in a state that mixes 0 and 1.
- SuperpositionThe property that lets a qubit be in both the 0 and 1 states at once.
- EntanglementThe property that ties two qubits together like one, so measuring one also settles the state of the other.
- Quantum error correctionA technique that bundles error-prone qubits together, finds the wrong ones and fixes them while the calculation goes on.
- Post-quantum cryptography (PQC)New encryption methods designed to be hard to break even for a quantum computer.
Common misunderstandings
MythQuantum computers do every calculation faster.
In fact They can only be faster at certain kinds of problems. For everyday work like writing documents or playing games, today's computers do better.
MythThe more qubits, the better the quantum computer.
In fact What matters more is how rarely the qubits make mistakes. The number of logical qubits that can fix their own errors shows real ability better.
MythEntanglement lets you send news faster than light.
In fact Even with entanglement, information cannot travel faster than light. The strength of quantum communication is that you can tell when someone has listened in.
Who to watch now
Organisations with the highest LastAI Index
- 1IBMIndex 49
- 2MicrosoftIndex 47
- 3Amazon Web ServicesIndex 38
- 4IonQIndex 32
- 5Rigetti ComputingIndex 32
The LastAI Index measures how widely something is used and known, from public data. It is recalculated every 15 minutes and is not a measure of quality or investment value. See the full ranking
Follow on the tech radar
News about each technology, company or person, in date order.
Recent milestones
The three latest events from the timeline. The timeline shows how the field got here.
Where to go next
This guide was written by AI and checked again for accuracy before publishing, and the English edition is translated from the Korean guide. Rankings change quickly, so they are not written into the text; 'Who to watch now' shows the LastAI Index as it is. Tell us if something is wrong. Report an errorLast updated