Fig. 3: iSWAP oscillations between two distant spin qubits.
From: Cavity-mediated iSWAP oscillations between distant spins
a, Pulse sequence for the measurement of iSWAP oscillations starting from |10〉. The two qubits are initialized in |00〉 by relaxation at the charge degeneracy point. Then, qubit 2 is isolated in the left dot for 500 ns, during which a π-pulse is applied to qubit 1. After 10 ns, qubit 2 is pulsed back into interaction, and both spins interact with each other for tint. After the interaction interval, qubit 2 is isolated in its left dot for 1 μs, where relaxation is expected to be slower, whereas qubit 1 is read out using a 400-ns-long probe tone. Subsequently, qubit 1 is isolated in its left dot and qubit 2 is read out using a 400 ns probe tone. b, The data points show the measured (change in) transmission, representative of the spin-up population for each spin, starting from |10〉. Each data point is averaged for 106 times. Here gs,1(2)/2π ≈ 21.5 MHz and Δ2s,1(2)/2π ≈ 65.5 MHz. The solid lines represent fits to the dispersive Hamiltonian model of equation (1) (with noise added; Supplementary Section D), from which we extract an interaction strength 2J/2π of 11.6 ± 0.2 MHz. c, Pulse sequence similar to that in a, but starting from |01〉. d, Similar data and fit as in b, but starting from |01〉. Here we extract 2J/2π = 11.8 ± 0.2 MHz.
