The Modular Universal Scalable Ion-trap Quantum Computer (MUSIQC) Program is a soon-to-be concluded collaborative effort to develop technologies in order to scale an ion-trap quantum computer. The modular vision of a largescale quantum computer consists of elementary logic units (ELUs) linked together by optical connections. Each ELU will have some qubit resources devoted to processing tasks while other qubits are devoted to communication links.
MIST group focuses on working with microfabricated surface electrode ion traps, which are designed and fabricated by Sandia National Laboratories. The potential for mass production with uniform behavior distinguishes this trapping technology from the macroscopic four rod traps commonly used. This also allows for more precise control of the electric field with smaller electrodes. Complicated trap geometries can be made giving the ability to shuttle the atoms and rearrange their order.
For individual addressing of qubits, microelectromechanical systems (MEMS) technology allows one to design movable micromirrors to focus laser beams on individual ions and steer the focal point in two dimensions. This system provides low optical loss across a broad wavelength range and can scale to multiple beams. To improve the fidelity of the single qubit gates, compensated pulse sequences are used.
Other past work includes using a custom high numerical aperture imaging lens for high speed, high efficiency state detection. Custom low noise control electronics have also been designed and assembled for digital and analog control of the experiments.
Current Work:
Fiber Coupling Scattered Ion Light
The custom high NA lens that was originally tested here for free space state detection was also designed to couple well into a UV single mode fiber optic. We are currently working on increasing this coupling efficiency for performing entanglement between two separate chambers, and testing the UV efficiency of SNSPD detectors (see the Novel Single Photon Detectors or Superdense Quantum Teleportation pages for more on SNSPDs).
Multiqubit Gates
Novel approaches to multiple qubit gates are being explored currently.
Co-trapping Barium and Ytterbium Ions
Barium can be used to sympathetically cool trapped ytterbium ions, eliminating the need for esonant light at the ytterbium frequencies for Doppler cooling. Barium can also be used as a communication qubit potentially. We are currently working on trapping both barium and ytterbium at the same time for these purposes.
Compact Interference Filter Laser Development
Semiconductor laser diodes are too spectrally broad to be compatible with atomic physics without some other frequency selective mechanisms. The interference filter laser utilizes a band-pass filter external to the laser diode to provide optical feedback and narrow the spectrum of the laser. The creation of compact low cost interefence filter lasers was explored.
Relevent Papers:
Scaling the Ion Trap Quantum Processor
Single qubit manipulation in a microfabricated surface electrode ion trap
Error compensation of single-qubit gates in a surface-electrode ion trap using composite pulses