Understanding and control of the spin relaxation time T1 is among the key challenges for spin-based qubits. A larger T1 is generally favored, setting the fundamental upper limit to the qubit coherence and spin readout fidelity. In GaAs quantum dots at low temperatures and high in-plane magnetic fields B, the spin relaxation relies on phonon emission and spinorbit coupling. The characteristic dependence T1 B5 and pronounced B-field anisotropy were already confirmed experimentally. However, it has also been predicted 15 years ago that atlow enough fields, the spinorbit interaction is replaced by the coupling to the nuclear spins, where the relaxation becomes isotropic, and the scaling changes to T1 B3. Here, we establish these predictions experimentally, by measuring T1 over an unprecedented range of magnetic fieldsmade possible by lower temperatureand report a maximum T1 57 15 s at the lowest fields, setting a record electron spin lifetime in a nanostructure.
Journal Article - Open Access
nature COMMUNICATIONS , 9, 3454, 01 Jan 0001, 01 Jan 0001,