David Awschalom of the University of Californa at Santa Barbara and colleagues trapped electrons in a seminconductor device made of layered gallium arsenide and aluminum gallium arsenide. By carefully adjusting the distribution of electron-transmitting aluminum across the device, they were able to create an energy barrier with sloping sides like a valley, instead of the usual box shape. When the researchers applied a voltage to the setup, the valley walls tilted like a seesaw. As electrons crossed from one material to the other through the well, quantum mechanical effects altered their spins according to how positive or negative the field was. "It's a scalable, controllable way to manipulate the electron's spin at the nanometer scale," Awschalom says. "Most schemes for quantum information processing require you to electrically tune the spin of the electron."
He adds that the very difficult next step would be to find a way to bind together the spin states of multiple electrons within these wells. But meeting this goal will require a lot of new physics, he says. "These devices will be a lab in which we can explore this physics."