  Due to the spin-orbital coupling in a semiconductor quantum dot, a freely
precessing electron spin produces a time-dependent charge density. This creates
a sizeable electric field outside the dot, leading to promising applications in
spintronics. The spin-electric coupling can be employed for non-invasive single
spin detection by electrical methods. We also consider a spin relaxation
mechanism due to long-range coupling to electrons in gates and elsewhere in the
system, and find a contribution comparable to, and in some cases dominant over
previously discussed mechanisms.
