Reconfigurable quadruple quantum dot linear array with tunable couplings and dispersive sensing

We discuss measurement results on a device that we show can demonstrate spin-based manipulation and readout in a multi-gate CMOS device. An array of four dot gates in series control the charge occupancy of their respective underlying quantum dots, while five independently tuneable exchange gates regulate their inter-dot coupling. Such a structure can form the basis of various qubit device configurations, whether that be a 4 quantum dot device or a 2 or 3 quantum dot device along with a corresponding sensing quantum dot.



The readout is performed using both DC measurement of the CMOS nanowire, as well as gate-based radio-frequency reflectometry readout. Two resonators, with superconducting spiral inductor and capacitor pairs designed in-house capable of delivering high quality factors, are connected to the dot gates to allow the reflectometry readout; the other two dot gates connect to microwave sources allowing pulses, suitable for real-time operation of the quantum dot.