Optimizing electrically controlled echo sequences for the exchange-only qubit

TL;DR

This paper compares different exchange-based echo sequences and optimization strategies for the exchange-only qubit, demonstrating that adaptation of these strategies is straightforward and performance varies slightly with noise spectra.

Contribution

It applies UDD and OFDD optimization strategies, originally for single-spin qubits, to exchange-only three-spin qubits, showing their effective adaptation.

Findings

Performance depends slightly on echo sequence choice.

Both Lorentzian and Ohmic noise spectra were considered.

Optimization strategies are straightforward to adapt.

Abstract

Recently, West and Fong [New J. Phys. 14, 083002 (2012)] introduced an echo scheme for an exchange-only qubit, which relies entirely on the exchange-interaction. Here, we compare two different exchange-based sequences and two optimization strategies, Uhrig dynamical decoupling (UDD) and optimized filter function dynamical decoupling (OFDD), which were introduced for a single-spin qubit and are applied in this paper to the three-spin exchange-only qubit. The calculation shows that the adaption of the optimization concepts can be achieved by straight-forward calculation. We consider two types of noise spectra, Lorentzian and Ohmic noise. For both spectra, the results reveal a slight dependence of the performance on the choice of the echo sequence.