Electron and nuclear spin control in semiconductors: progress towards robust environment Hamiltonian engineering

• Speaker: Kim, Dohun (Seoul National University)

The electron and nuclear spin degrees of freedom in solids form natural bases for constructing quantum two level systems, or qubits. The electron spin qubit offers a route for fast manipulation of spins using magnetic resonance, but generally suffers from fast dephasing due to strong coupling to the environment, especially nuclear spin bath, where decoherence dynamics is often non-Markovian. On the other hand, nuclear spins in semiconductors are attracting great interest due to their extremely long coherence time, but generally requires interaction to electron spins to achieve quantum control. In this talk I will discuss experimental progresses, with examples in GaAs 2-dimensional electron gas – based quantum dots and nitrogen-vacancy (NV) centers in diamond, towards controlling nuclear spins via hyperfine interaction with electron spins. In quantum dot system, spatially distributed electron wavefunctions sees millions of nuclear spins, where controlling spin bath polarization is achieved using electrical pulse-based dynamic nuclear polarization scheme. In diamond NV center, hyperfine interaction in combination with optical illumination is used to polarize individual nuclear spins around electron spin. Introducing these concepts, I will further discuss implication of these experiments toward efficient environment Hamiltonian engineering.