Trapped Ion Qubits

Ytterbium, calcium, beryllium, and strontium ions

Trapping Technique

1. Ions are trapped using radiofrequency (RF) and DC electric fields in Paul or Penning traps
2. Paul trap uses oscillating RF field to create a pseudopotential that traps ions
3. Penning trap uses static magnetic field combined with DC electric field
4. Ions are laser-cooled to near ground state of motion
5. Multiple ions can be trapped in linear or 2D arrays with precise spacing
6. Ion chains form a crystal structure due to Coulomb repulsion

Gate Mechanism

1. Single-qubit gates performed via laser or microwave pulses addressing individual ions
2. Laser pulses drive optical or hyperfine transitions between qubit states
3. Microwave pulses used for hyperfine qubits, avoiding photon scattering
4. Two-qubit gates use shared motional modes (phonons) as a quantum bus
5. Mølmer-Sørensen gate uses bichromatic laser fields to couple qubits via motion
6. Direct Coulomb interaction can also mediate gates between nearby ions