Spin-dependent transport in silicon/silicon-germanium quantum dots

It is intriguing that silicon, the material at the heart of modem classical electronics, also has properties that are well suited to quantum electronics. These properties include weak spin-orbit coupling and the existence of zero-nuclear spin isotopes. This synergy between quantum and classical properties offers the possibility that silicon quantum dots potentially could be used as quantum bits, if high-quality, extremely stable devices can be fabricated and measured. In this talk, we will present data demonstrating silicon/silicon-germanium quantum dots containing individual electrons. Single-electron occupation is confirmed through the use of integrated charge sensing. We will also present measurements of Si/SiGe double quantum dots, in which we have recently observed Pauli spin blockade a¿¿¿ the suppression of transport current through a double quantum dot due to long lived spin states. Reversing the flow of current leads to a new effect in which long spin lifetimes enhance, rather than suppress, the flow of current through the double dot.