Concatenated Control Sequences based on Optimized Dynamic Decoupling

TL;DR

This paper introduces a combined quantum control strategy using concatenated and optimized dynamic decoupling sequences to effectively suppress unwanted couplings and decoherence in quantum systems, enhancing their isolation.

Contribution

It presents a novel method that merges concatenation and optimization of pulse intervals, reducing the number of pulses needed for high-order suppression in quantum control.

Findings

Suppression of longitudinal relaxation and transverse dephasing.

Exponential growth in pulses reduces to square root with concatenation.

Polynomial growth achieved with an approximate scheme.

Abstract

Two recent developments in quantum control, concatenation and optimization of pulse intervals, are combined to yield a strategy to suppress unwanted couplings in quantum systems to high order. Longitudinal relaxation and transverse dephasing can be suppressed so that systems with a small splitting between their energy levels can be kept isolated from their environment. The required number of pulses grows exponentially with the desired order but is only the square root of the number needed if only concatenation is used. An approximate scheme even brings the number down to polynomial growth. The approach is expected to be useful for quantum information and for high-precision nuclear magnetic resonance.