Double quantum dot as detector of spin bias

It was proposed that a double quantum dot can be used to be a detector of spin bias. Electron transport through a double quantum dot is investigated theoretically when a pure spin bias is applied on two conducting leads contacted to the quantum dot. It is found that the spin polarization in the left and right dots may be induced spontaneously while the intra-dot levels are located within the spin bias window and breaks the left-right symmetry of the two quantum dots. As a result, a large current emerges. For an open external circuit an charge bias instead of a charge current will be induced in equilibrium, which is believed to be measurable according to the current nanotechnology. This method may provide a practical and whole electrical approach to detect the spin bias (or the spin current) by measuring the charge bias or current in a double quantum dot.