Physics you can poke
Small interactive demos of the ideas behind trapped-ion quantum computing. No equations required, but they’re there if you want them.
Laser-cool an ion
A trapped ion is sloshing back and forth. Each photon it absorbs from the laser pushes it to the right. Fire when it’s moving toward the laser (left) and you slow it down. Fire when it’s moving away and you speed it up. Get the energy into the green zone as fast as you can. Hold the button, press on the picture, or hold Space.
How real labs do it: tune the laser slightly below the atom’s resonance (red detuning). The Doppler shift brings it into resonance only for an ion moving toward the beam, so the laser automatically “fires” at the right moments. Random recoil from re-emitted photons sets a floor on how cold you can get, called the Doppler limit.
Rabi flopping
Driving a qubit with resonant light rotates its state around the Bloch sphere, from |0⟩ to |1⟩ and back. Detune the drive and the rotation axis tilts: the flopping speeds up but never fully reaches |1⟩. A “π-pulse” is a flip that lasts exactly half a cycle.
Build a Coulomb crystal
Ions repel each other but are held by the trap. Squeeze the trap hard sideways and they line up in a chain, which is what you want for a quantum computer. Loosen it and the chain buckles into a zigzag, then a 2D crystal. Click to drop in more ions.
More to play with
- Normal-mode explorer: solve and animate the vibrational modes of a chain of up to 30 ions.
- Headphone power calculator: how many volts and milliamps does your headphone really need?