Pulse-gated quantum dot hybrid qubit
  A quantum dot hybrid qubit formed from three electrons in a double quantum dot has the potential for great speed, due to presence of level crossings where the qubit becomes charge-like. Here, we show how to take full advantage of the level crossings in a pulsed gating scheme, which decomposes the spin qubit into a series of charge transitions. We develop one and two-qubit dc quantum gates that are simpler than the previously proposed ac gates. We obtain closed form solutions for the control sequences and show that these sub-nanosecond gates can achieve high fidelities. 
Teck Seng Koh, John King Gamble, Mark Friesen, M. A. Eriksson, S. N.   Coppersmith
quant-ph cond-mat.mes-hall