Atomtronics:: Ultracold-atom analogs of electronic devices

Atomtronics focuses on atom analogs of electronic materials, devices, and circuits. A strongly interacting ultracold Bose gas in a lattice potential is analogous to electrons in solid-state crystalline media. As a consequence of the gapped many-body energy spectrum, cold atoms in a lattice exhibit insulatorlike or conductorlike properties. P-type and N-type material analogs are created by introducing impurity sites into the lattice. Current through an atomtronic wire is generated by connecting the wire to an atomtronic battery which maintains the two contacts at different chemical potentials. The design of an atomtronic diode with a strongly asymmetric current-voltage curve exploits the existence of superfluid and insulating regimes in the phase diagram. The atom analog of a bipolar junction transistor exhibits large negative gain. Our results provide the building blocks for more advanced atomtronic devices and circuits such as amplifiers, oscillators, and fundamental logic gates.