Fig. 1: A germanium hole two-qubit system.

a, Schematic drawing of the three-quantum-dot device. We define qubits Q1 and Q2 underneath plunger gates P1 and P2, respectively, that can be read out using the nearby charge sensor (CS) defined by gates SP, SB1 and SB2. The coupling between the qubits is controlled by B12, whereas the coupling of Q1 (Q2) to its respective reservoir is controlled by RB1 (RB2). We record the response of the charge sensor on the computer (PC) by measuring the differential current between the source (S) and drain (D) contacts, measured using transimpedance amplifiers A. V_S, source bias voltage; V_D, drain bias voltage. b, Two-quantum-dot charge stability diagram as a function of two virtualized plunger gate voltages \({V}_{\overline{{{{{\rm{P}}}}}{1}}}\) and \({V}_{\overline{{{{{\rm{P}}}}}{2}}}\), with the colour corresponding to the charge sensor current I_sensor. The different charge configurations are indicated by the numbers in parentheses (N₁, N₂). The direction of the virtual detuning ϵ and on-site energy U axes are indicated. c, Spin-to-charge conversion is performed via latched Pauli spin blockade readout. The pulses applied to the ϵ and U axes, as well as the qubit drive pulses V_RF, are shown in the top panels. The spin state ❘ψ❭ is initialized in the \(\left\vert \downarrow \uparrow \right\rangle\) state by adiabatically sweeping across the interdot transition (1 → 2). Next we apply either no pulse (left panel) or an X_π pulse (right panel) to Q2 (2) and sweep (2 → 3) to the readout point (V_ϵ,3, V_U,3), which is rasterized to compose the entire map. Red lines indicate (extended) lead transition lines, whereas the white lines correspond to the interdot transition lines of the quantum-dot ground (solid) and excited (dashed) states.