Long coherence of electron spins coupled to a nuclear spin bath

Understand

Qubits, the quantum mechanical bits required for quantum computing, must retain their fragile quantum states over long periods of time.

• In many types of electron spin qubits, the primary source of decoherence is the interaction between the electron spins and nuclear spins of the host lattice.
• For electrons in gate defined GaAs quantum dots, previous spin echo measurements have revealed coherence times of about 1 $\mu$s at low magnetic fields below 100 mT.
• Here, we show that coherence in such devices can actually survive to much longer times, and provide a detailed understanding of the measured nuclear spin induced decoherence.