Eliminating Leakage Errors in Hyperfine Qubits

Understand

Population leakage outside the qubit subspace presents a particularly harmful source of error that cannot be handled by standard error correction methods.

• Using a trapped $^{171}$Yb$+$ ion, we demonstrate an optical pumping scheme to suppress leakage errors in atomic hyperfine qubits.
• The selection rules and narrow linewidth of a quadrupole transition are used to selectively pump population out of leakage states and back into the qubit subspace.
• Each pumping cycle reduces the leakage population by a factor of $\sim3$, allowing for an exponential suppression in the number of cycles.