A new type of correlation between the spin and momentum of an electron
arises in an asymmetric quantum well upon photoexcitation. Even if th
e exciting light is unpolarized, the expectation value of the electron
spin turns out to be nonzero. It is directed perpendicular to the ele
ctron quasimomentum in the plane of the well. A longitudinal magnetic
field disrupts the correlation, as can be seen in the intensity of the
hot luminescence.