Atoms, Energy Levels and Rabi Oscillations
An atom can only hold certain energies, its energy levels, so it gives off and takes in light only at matching colors. Shine light tuned to the gap between two levels and the atom swings smoothly from the lower level to the upper one and back, a Rabi oscillation. That controllable swing is exactly how qubits made from atoms and ions are steered.
Why do quantum computers use atoms at all?
Every atom of the same kind is exactly the same. Two calcium-40 atoms made in different stars are perfect copies. No factory can make parts that match that well. That makes atoms great qubits.
Trapped-ion and neutral-atom quantum computers use real atoms. Superconducting qubits are tiny circuits that behave like artificial atoms. To steer any of them, you need two ideas from this chapter: energy levels, and the swing called a Rabi oscillation.
- Why does each gas glow its own colors?
- Worked example: compute the red line of hydrogen
- What is a Rabi oscillation?
- How long should you shine the light? Work the numbers.
- Run it: a π/2 pulseINTERACTIVE
- Try this: a π pulseINTERACTIVE
- Try this: a 2π pulse, and a short oneINTERACTIVE
- How do energy levels become the world's best clocks?
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