Measurements of capacitive coupling in two double dots in Si/SiGe for application in two qubit gates

We present measurements of a Si/SiGe quantum dot device made with overlapping self-oxidized Al gates. The device includes a linear array of four quantum dots and two auxiliary dots for charge sensing. The dots have a lithographic pitch of 130 nm and are separated from the gates by a 30 nm SiGe spacer and 5 nm of aluminum oxide deposited by ALD. We measure the charge noise in all six dots and observe a power spectral density that is approximately 1/f in the 1-200 Hz range with a chemical potential noise amplitude of 1-2 μeV/Hz^1/2 at 1 Hz. We tune the device to form two tunnel-coupled double dots and observe the capacitive coupling with both double dots at the (0,1)-(1,0) polarization line. We measure a detuning shift of ~8 GHz due to the change in polarization of the adjacent double dot, demonstrating the potential of the system for coherent two-qubit coupling via capacitive interaction.