2014/04/30 by Jo-Tzu Hung, Jianjia Fei, Mark Friesen +1 · 2 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.90.045308
published as Phys. Rev. B 90, 045308 (2014) · 15 pages, 8 figures
openalex publication_date 2014/07/18 · arxiv created 2014/07/22 · arxiv updated 2014/07/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study three-electron-spin decoherence in a semiconductor triple quantum dot with a linear geometry. The three electron spins are coupled by exchange interactions J12 and J23, and we clarify inhomogeneous and homogeneous dephasing dynamics for a logical qubit encoded in the (S=1/2,Sz=1/2) subspace. We first justify that qubit leakage via the fluctuating Overhauser field can be effectively suppressed by sufficiently large Zeeman and exchange splittings. In both J12=J23 and J12\ensuremath≠J23 regimes, we construct an effective pure dephasing Hamiltonian with the Zeeman splitting EZ\ensuremath≫J12,J23. Both effective Hamiltonians have the same order of magnitude as that for a single-spin qubit, and the relevant dephasing time scales (T2*,TFID, etc.) are of the same order as those for a single spin. We provide estimates of the dynamics of three-spin free induction decay, the decay of a Hahn spin echo, and the decay of echoes from a CPMG pulse sequence for GaAs quantum dots.