Title: Quantum information processing with 4 electrons and 10^6 nuclei

 

Abstract: Individual spins in semiconductors can retain their quantum phase coherence for times exceeding one second. Such long coherence times makes spins a versatile platform for exploring quantum information processing and condensed matter physics. I will discuss recent work exploiting the joint spin-state of two electrons in a GaAs double quantum dot as a spin qubit. This qubit is highly sensitive to its local magnetic environment. We leverage this sensitivity to precisely measure the statistically fluctuating nuclear polarization in the semiconductor crystal. Surprisingly, we can harness the random nuclear polarization in the semiconductor to suppress electrical decoherence in the spin qubit, enabling a high-fidelity entangling gate between spin qubits.