Fig. 1: Device and basic operation.
From: High-fidelity spin qubit operation and algorithmic initialization above 1 K
Readout probability is unscaled in all data. a, Schematic experimental setup with a scanning electron micrograph of a device nominally identical to that used in this work. The RFSET, the microwave (MW) antenna and other active gate electrodes are highlighted with colours. An external d.c. magnetic field B0 and the antenna-generated a.c. magnetic field B1 are indicated with arrows. The system operates at T = 1 K, unless otherwise specified. b, Device cross-section schematic with the intended quantum dot location, the electron-spin qubits Q1, Q2 and the RFSET as the charge sensor indicated. c, Charge stability diagram as a function of P1, P2 voltage detuning and the J gate voltage VJ, showing the operation regime. The operation points for readout (M), single-qubit (X, Z, I) and two-qubit controlled phase (CZ) operation are labelled as star, triangle and square, respectively. The insets schematically show the operations that are performed at each position. d, Probability of reading out a blockaded state, Pblockade, when preparing |↓↓⟩ and reading out at different VJ and P1, P2 voltage detuning. The readout location for subsequent experiments is set amid the readout window that appears as the high-Pblockade region. e, Rabi oscillations at VJ = 1.1 V as a function of microwave frequency fMW and pulse time tMW. f, Decoupled controlled phase (DCZ) oscillations as a function of exchange time texchange and VJ. g, Calibration of the single-qubit X(π/2) gates. h, Calibration of the two-qubit DCZ gate. a.u., arbitrary units. RF, radiofrequency. Scale bar, 100 nm (a).
