Spectroscopy of Valley Splitting in a Silicon/Silicon-Germanium   Two-Dimensional Electron Gas
  The lifting of the two-fold degeneracy of the conduction valleys in a strained silicon quantum well is critical for spin quantum computing. Here, we obtain an accurate measurement of the splitting of the valley states in the low-field region of interest, using the microwave spectroscopy technique of electron valley resonance (EVR). We compare our results with conventional methods, observing a linear magnetic field dependence of the valley splitting, and a strong low-field suppression, consistent with recent theory. The resonance linewidth shows a marked enhancement above $T\simeq 300$ mK. 
Srijit Goswami, Mark Friesen, J. L. Truitt, Charles Tahan, L. J.   Klein, J. O. Chu, P. M. Mooney, D. W. van der Weide, S. N...