Dynamical Decoupling in Triangular Exchange-Only Spin Qubits

Full-permutation dynamical decoupling (DD) in triple quantum dot (TQD) exchange-only (EO) spin qubits has been experimentally demonstrated to significantly enhance qubit lifetimes [1]. Typical linear dot layouts have incomplete inter-spin coupling which leads to dephasing from locally varying magnetic fields between the uncoupled dots. Our group has shown the electrostatic and coherent operation of a triangular layout with complete inter-spin coupling and average single-qubit gate fidelity of 99.84% [2]. We now present novel triangular EO qubit DD sequences which rephase quasistatic collinear magnetic noise for any input Bloch vector. Analytic formalisms and numeric simulations are used to evaluate various EO qubit DD sequences for a broad range of exchange and magnetic noise spectra. This analysis suggests triangular DD sequences may be advantageous over linear counterparts in qubits limited by hyperfine fluctuations.



[1] B. Sun et al., “Full-Permutation Dynamical Decoupling in Triple-Quantum-Dot Spin Qubits,” PRX Quantum 5, 020356 (2023).

[2] E. Acuna et al., “Coherent control of a triangular exchange-only spin qubit,” arXiv:2406.03705 (2024).