Controlled resonant tunneling in a coupled double-quantum-dot system

The authors investigate electrostatic coupling between two double quantum dots (DQDs) defined in an Al Ga As ∕ Ga As heterostructure by measuring the correlation between resonant tunneling currents through the DQDs. Resonant tunneling in one DQD can be controlled by the charge state of the other DQD. This controlled resonant tunneling is consistent with the capacitance model for the geometry and can be used to investigate the statistics of single-electron charge states in the DQD. The observed electrostatic coupling is strong enough to perform two-qubit quantum gates both for charge- and electron-spin-based qubit schemes.