  Increasing the separation between semiconductor quantum dots offers scaling
advantages by fa- cilitating gate routing and the integration of sensors and
charge reservoirs. Elongated quantum dots have been utilized for this purpose
in GaAs heterostructures to extend the range of spin-spin interactions. Here,
we study a metal-oxide-semiconductor (MOS) device where two quantum dot arrays
are separated by an elongated quantum dot (340 nm long, 50 nm wide). We monitor
charge transitions of the elongated quantum dot by measuring radiofrequency
single-electron currents to a reservoir to which we connect a lumped-element
resonator. We operate the dot as a single electron box to achieve charge
sensing of remote quantum dots in each array, separated by a distance of 510
nm. Simultaneous charge detection on both ends of the elongated dot
demonstrates that the charge is well distributed across its nominal length,
supported by the simulated quantum-mechanical electron density. Our results
illustrate how single-electron boxes can be realised with versatile foot-
prints that may enable novel and compact quantum processor layouts, offering
distributed charge sensing in addition to the possibility of mediated coupling.
