New approach transports trapped ions to create entangling gates

Trapped ions excited with a laser beam can be used to create entangled qubits in quantum information systems but addressing several stationary pairs of ions in a trap requires multiple optical switches and complex controls. Researchers at Georgia Tech Research Institute moved calcium ions held in a surface electrode trap through a stationary bichromatic optical beam potentially integrating the existing transport control into quantum logic operations. Measurements showed that the entangled quantum state of the two qubits transported through the optical beam had a fidelity comparable to entangled states produced by stationary gates performed in the same trapping system. The potential advantage of moving the ions into a single beam is that a single beam can be reflected back and forth across a trap, interact with many ions, reducing the need for multiple beams and control complexity. This opens the possibility of sharing the light among multiple sites within a larger structure, without having an optical switch for every pair of ions, and  the intensity of the interaction can be controlled by the movement of ions through the beam rather than by adjusting the laser pulses. A disadvantage is that the ions don’t remain in the most intense portion of the beam, hence require more intense beam to provide power to the ions…read more. (Accepted) TECHNICAL ARTICLE