Search

The article focuses on the study of J. Bylander and colleagues which examines the quantum dynamics of a superconducting flux qubit with the use of a superconducting quantum interference device (SQUID). It says that the qubit will have decoherence problems if it freely evolves in an uncontrolled environmental noise. It mentions that the study allows noise power spectral density reconstruction and comparison against known noise mechanism.

Recent studies have shown that applying a sequence of Hahn spin-echo pulses to a qubit system at judiciously chosen intervals can, in certain noise environments, greatly improve the suppression of phase errors compared to traditional dynamical decoupling approaches. By enforcing a simple analytical condition, we obtain sets of dynamical decoupling sequences that are designed for optimized noise filtration, but are independent of the noise spectrum up to a single scaling factor set by the coherence time of the system. These sequences are tested in a model qubit system, ;{9}Be;{+} ions in a Penning trap. Our combined theoretical and experimental studies show that in high-frequency-dominated noise environments with sharp high-frequency cutoffs this approach may suppress phase errors orders of magnitude more efficiently than comparable techniques can.