Charge redistribution spectroscopy as a probe of spin phenomena in quantum dots

Two transport techniques are described for performing charge redistribution spectroscopy at a fixed electron number. In the first method we simply apply the well established 'Cambridge' QPC charge detector technique to a dot with no leads to external reservoirs. In the second technique we use two (lots in series in the regime where the electrochemical potential of only one of the dots is aligned with the external leads. In this case the transport involves cotunneling processes through the second dot. Charge rearrangements occurring in one dot are picked up through shifts in the electrochemical potential of the other. We perform proof of concept demonstrations using well characterised transitions in the vicinity of filling factor 2 to confirm that both techniques can be used for charge redistribution spectroscopy. We discuss why such spectroscopy can provide new information about complex many-body spin phenomena in quantum dots.