Science
What is Quantum entanglement?
Quantum entanglement is a link between particles so that measuring one instantly fixes the matching property of the other, no matter how far apart they are. The particles share one quantum state — what Einstein famously called 'spooky action at a distance.'
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains quantum entanglement.
Key things to understand
- 1Two entangled particles act as a single system: measure one and you instantly know the other's correlated value.
- 2It cannot send usable information faster than light — you can't control which result you get.
- 3Confirmed by experiments testing Bell's inequalities, ruling out hidden pre-set values.
- 4It is the backbone of quantum computing, quantum cryptography, and quantum teleportation.
Frequently asked questions
- Does entanglement allow faster-than-light communication?
- No. The outcomes are random, so you can't encode a message in them; comparing results still needs an ordinary, light-speed-limited channel.
- Why did Einstein dislike it?
- He called it 'spooky action at a distance' and argued quantum theory was incomplete — but experiments have repeatedly confirmed entanglement is real.
- How is entanglement used?
- It powers quantum computers' speed, ultra-secure quantum key distribution, and lab demonstrations of quantum teleportation.