While electron spins in silicon heterostructures make attractive qubits, little is known about the coherence of electrons at the Si/ SiO2 interface. We report spin relaxation (T1) and coherence (T 2) times for mobile electrons and natural quantum dots at a S 28 i/ SiO2 interface. Mobile electrons have short T1 and T 2 of 0.3 μs at 5 K. In line with predictions, confining electrons and cooling increases T1 to 0.8 ms at 350 mK. In contrast, T 2 for quantum dots is around 10 μs at 350 mK, increasing to 30 μs when the dot density is reduced by a factor of two. The quantum dot T 2 is shorter than T1, indicating that T2 is not controlled by T1 at 350 mK but is instead limited by an extrinsic mechanism. The evidence suggests that this extrinsic mechanism is an exchange interaction between electrons in neighboring dots.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Nov 19 2010|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics