Experimental Work Towards an Individually-Addressed-Ion Penning Trap Quantum Simulator

Trapped ions constitute a robust platform for quantum simulation. Penning traps provide a means to increase the number of trapped ion qubits to many hundreds or even thousands by confining the particles in a planar configuration. Penning traps utilize static electric and magnetic fields for confining ions which provide the advantage of reduced motional heating and state-of-the-art motional frequency stability. We designed and operate a compact Penning trap using rare earth permanent magnets for increased optical access to the trapped ⁴⁰Ca⁺ ions as compared to superconducting magnet systems. However, the trapped ions rotate in the trap’s magnetic field making individual addressing and readout challenging. We implement the proposed technique [1, 2] to use a triangular rotating wall potential to lock the rotation frequency and phase of the planar trapped ⁴⁰Ca⁺ crystal with minimal structural defects. A Tpx3Cam collects the scattered photons’ positions and incident times to perform individual readout of each ion’s state. We perform the individual addressing of metastable (D_5/2) qubits using either stimulated-Raman interactions or a focused AC Stark shifting laser beam combined with global microwave rotations. We detail our work towards a global light-shift entangling gate with applications including the quantum approximate optimization algorithm (QAOA).

[1] Khan, A., Yoshimura, B. and Freericks, J. K. Phys. Rev. A 92, 043405 (2015).

[2] Dubin, D. H. E. Phys. Rev. A 88, 013403 (2013).