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Ions on a Chip

January 12, 2010

JQI scientists are testing a new chip, fabricated at Sandia National Laboratories, that will trap ions for study. Trapped atomic ions are widely regarded as a highly promising hardware platform for quantum computing, with each atom holding a single quantum bit (qubit) of information.

"However," says JQI Fellow Chris Monroe, "it is tricky to scale ion-trap structures to large numbers -- say, thousands -- of qubits, as current designs have bulky electrodes that are noisy and have surface and alignment defects."

Future ion trap structures will likely be fabricated using semiconductor processes in order to support hundreds or thousands of pristine and precisely-aligned electrodes, borrowing techniques from microelectromechanical systems. The first demonstrated monolithic ion trap chip was fabricated at the Laboratory for Physical Sciences in 2006, and now the ion trap group at JQI is again moving in this direction with a collaboration with Sandia National Laboratory with support from the IARPA Ion Trap Foundry Project.

Pictured is the latest Sandia "surface" ion trap, fabricated from Si/SiO2 chip-growing techniques and installed in the JQI ion trap laboratory. The chip trap comes mounted on a standard chip-carrier that is simply plugged into a receptacle under ultra-high vacuum. "The center of the chip shows what looks like a diagonal railroad track of 20 segmented electrodes, that should allow many ions to be confined and shuttled through the device," Monroe says. "The atomic ions will be confined in a straight line, floating about 0.1 millimeters above the surface and aligned along the 0.5 millimeter-wide railroad track. Laser beams are directed along the surface, and the fluorescence from the ions can be collected along the view of the picture."

JQI researchers will trap and laser cool large strings of atomic ion qubits in this structure, and characterize its use for quantum simulations of magnetic order between interacting spins, as well as quantum logic gates between ions for quantum computing.

The ion trap research team includes D. Stick and M. Blain of Sandia National Laboratories, and J. Sterk, L. Luo, A. Manning, and C. Monroe from JQI.