Entanglements
Want the singlet back? With both Qubis on, hold one in each hand and gently bump them together. A flash on both spheres confirms they're entangled again.
This will create a very specific entangled state, called the singlet state. We will learn about it later.
It doesn't matter what you've done before: every bump resets the state. You can do it as many times as you need, and it doesn't change anything.
Contact force matters. After a couple of tries you'll find the right strength.
Calibrating the bump
- Too gentle: nothing happens. Try harder.
- Just right: both spheres flash. You're entangled.
- Too hard: they vibrate (that's a measurement rather than a bump). Try lighter.