Fundamental limits of electron and nuclear spin qubit lifetimes in an isolated self-assembled quantum dot

Abstract Combining external control with long spin lifetime and coherence is a key challenge for solid state qubits. Tunnel coupling electron Fermi reservoir provides robust charge in semiconductor quantum dots, but results undesired relaxation of nuclear spins through mechanisms that lack complete understanding. Here, we unravel the contributions tunnelling-assisted phonon-assisted by systematically adjusting tunnelling wide range, including limit an isolated dot. These experiments reveal fundamental limits trade-offs dot dynamics: while reduced can be used to achieve qubit lifetimes exceeding 1 s, optical initialisation fidelity below 80%, limited Auger recombination. Comprehensive understanding electron-nuclear attained here roadmap design optimal operating conditions