Dynamical Decoupling — Pulse Sequences

Protecting qubit coherence with timed π-pulses. CPMG beats Hahn echo for 1/f noise by targeting low-frequency dephasing.

Parameters

No decoupling
Hahn Echo (1 π-pulse)
CPMG (N π-pulses)
Key result: CPMG extends T₂ by ~Nα for 1/fα noise.
For white noise: T₂eff ≈ T₂.
For 1/f noise: CPMG suppresses low-f dephasing exponentially.