Coherent control and quantum simulation in large ion crystals
We describe experimental efforts aimed at the realization of nonlinear multipartite interactions using planar ion crystals in a Penning trap. This system benefits from the ability to confine large ion arrays with regular and stable crystalline order without the need for significant trap engineering efforts. Of particular interest is the triangular lattice which arises naturally in a two-dimensional ion crystal, and which is known to show frustration in the presence of spin-spin interactions. Coherent control over trapped ion qubits is demonstrated and characterized through randomized benchmarking, yielding a single-bit operational fidelity of 99.92%. Coherence limits in this system are explored through dynamical decoupling protocols, dramatically suppressing decoherence. A global entangling interaction is engineered using state-dependent optical dipole forces, resulting in a simple distance-independent Ising interaction, and we observe hallmark signatures of spin-motional, and spin-spin entanglement in arrays approaching ~150 ions. Experimental challenges such as the influence of spontaneous emission are discussed, and a new theoretical framework to fully account for dephasing induced by elastic Rayleigh scattering is presented.