Dipolar superfluidity in electron-hole bilayer systems

Bilayer electron-hole systems, where the electrons and holes are created via doping and are confined to separate layers, undergo excitonic condensation when the distance between the layers is smaller than the typical distance between the particles within the layer. We argue that the excitonic condensate is a novel dipolar superfluid in which the phase of the condensate couples to the gradient of the vector potential. We predict the existence of a dipolar supercurrent which can be tuned by an in-plane magnetic field. Thus the dipolar superfluid offers an example of excitonic condensate in which the composite nature of its constituent excitons is manifest in the macroscopic superfluid state. We also discuss various properties of this superfluid including the role of vortices.

A pseudo-spin surface-acoustic-wave quantum computer

A modification to the surface-acoustic-wave quantum computer is described. The use of pseudo-spin qubits is introduced as a way to simplify the fabrication and programming of the computer. A form of optical readout that relies on the electrons in each surface-acoustic-wave minimum recombining with holes in a two-dimensional hole gas is suggested as a means to measure the output. The suggested modification would allow the quantum computer to be made smaller and to operate faster.