A guided light system for agile individual addressing of Ba⁺ qubits with 10⁻⁴ level intensity crosstalk

Abstract

Trapped ions are one of the leading platforms for quantum information processing, exhibiting the highest gate and measurement fidelities of all contending hardware. In order to realize a universal quantum computer with trapped ions, independent and parallel control over the state of each qubit is necessary. The manipulation of individual qubit states in an ion chain via stimulated Raman transitions generally requires light focused on individual ions. In this manuscript, we present a novel, guided-light individual addressing system for hyperfine Ba+ qubits. The system takes advantage of laser-written waveguide technology, enabled by the atomic structure of Ba+, allowing the use of visible light to drive Raman transitions. Such waveguides define the spatial mode of light, suppressing aberrations that would have otherwise accumulated in a free-space optics set up. As a result, we demonstrate a nearest neighbor relative intensity crosstalk on the order of 10−4, without any active aberration compensation. This is comparable to or better than other previous demonstrations of individual addressing. At the same time, our modular approach provides independent and agile control over the amplitude, frequency, and phase of each channel; combining the strengths of previous implementations.

Trapping Ba+ with seven-fold enhanced efficiency utilizing an autoionizing resonance

“…Additionally, barium has been demonstrated as a qudit, controlling and reading out up to 13-levels [2] by taking advantage of its unusually long-lived metastable 5 d 2 D 5/2 state [3]. The flexibility of the atomic structure in barium and the visible wavelengths used to drive the electric-dipole transitions are also attractive from a practical perspective [4]. All of these key features of barium, coupled with extraordinary experimental state-preparation and measurement results [5][6][7][8] have captured the attention of researchers and motivated the trapping of barium in the most sophisticated surface traps as a front-running platform for quantum information processing [9][10][11][12].…”