Quantum Computing
Quantum computers use qubits that can be 0 and 1 at once.
About this topic
Quantum computing uses the laws of quantum physics to process information in new ways. Classical computers use bits that are either 0 or 1. Quantum computers use qubits, which thanks to superposition can be in a combination of 0 and 1 until measured. Entanglement links qubits so their states are correlated, and interference is used to boost correct answers and cancel wrong ones.
This does not mean a quantum computer tries every answer at once and simply picks the right one; algorithms must be cleverly designed. Shor's algorithm could factor large numbers far faster than known classical methods, which threatens some current encryption such as RSA, while Grover's algorithm speeds up searching. Quantum computers may also simulate molecules for new medicines and materials.
Today's machines are small and noisy: qubits are fragile and need extreme cold and isolation, and errors are common, so building large reliable ones is a major challenge. A common misconception is that quantum computers will replace ordinary computers or make everything faster; they are only expected to help with certain problems. Researchers are developing post-quantum cryptography to protect data in the future. It is an exciting field where physics, maths and computer science meet.
Key ideas
- Superposition and entanglement
- Good at some special problems
- Still experimental
Quick check
Use cases: where Quantum Computing helps
- Homework: review the key idea behind Quantum Computing before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Quantum Computing without notes.
- Visual learning: play with the interactive lab to see how Quantum Computing changes when you adjust its inputs.
- Teaching a friend: explain Quantum Computing in your own words, then compare your version with the key ideas.
Computing ideas run phones, search engines, games and the wider internet.
Frequently asked questions
What is Quantum Computing?
Quantum computers use qubits that can be 0 and 1 at once.
What will I learn in Quantum Computing?
Superposition and entanglement. Good at some special problems. Still experimental.
Is Quantum Computing part of Computer Science?
Yes. It is one of 80 Computer Science topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Quantum Computing lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Quantum Computing?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.