Fig. 1: Two-qubit device and symmetry operating point.
From: Quantum logic with spin qubits crossing the surface code threshold
a, Scanning electron microscopy images of a device similar to that used here, showing the quantum dot gate pattern and the micromagnet on top (the device used in the experiment has an additional screening gate above the fine gates17). The scale bar in the left panel denotes 500 nm. The scale bar in the right panel denotes 100 nm. b, Control paths for determining the symmetry operation point in the charge-stability diagram. (M, N) represent the number of electrons in the dots underneath the tip of LP and RP, respectively. a.u., arbitrary units. c, Pulse sequence schematic of a decoupled controlled-phase operation interleaved in a Ramsey interference sequence on Q1. d, Spin-up probability of Q1 after the Ramsey sequence in c, as a function of the detuning in the double-dot potential and the total duration of the barrier voltage pulses.
