Science Daily January 27, 2023
Optically active semiconductor quantum dots have unparalleled photonic properties, but also modest spin coherence limited by their resident nuclei. The nuclear inhomogeneity has thus far bound all dynamical decoupling measurements to a few microseconds. An international team of researchers (UK, Austria) eliminated the inhomogeneity using lattice-matched GaAs–AlGaAs quantum dot devices and demonstrated dynamical decoupling of the electron spin qubit beyond 0.113(3) ms. Leveraging the 99.30(5)% visibility of our optical π-pulse gates, we use up to Nπ = 81 decoupling pulses and find a coherence times hundreds of microseconds. This scaling manifests an ideal refocusing of strong interactions between the electron and the nuclear spin ensemble, free of extrinsic noise, which holds the promise of lifetime-limited spin coherence. According to the researchers their work may lead to devices that enable the creation of entangled light states for all-photonic quantum computing and allow foundational quantum control experiments of the nuclear spin ensemble…read more. TECHNICAL ARTICLE
Optically addressable spin in a GaAs–AlGaAs QD. Credit: Nature Nanotechnology (2023)