Single- and two-qubit operations on an atomic qubit array

Tian Xia, Kara Maller, Martin Lichtman +4 more

Martin Lichtman

Abstract : This report presents the results of the MQCO project and capstone extension during which a 2D array of neutralatom qubits was developed. The array was used to demonstrate high fidelity single qubit operations (F0.99-0.999)and moderate fidelity two-qubit entanglement, F=0.73. Technology development investigated compact lasersystems for Cs atom control, high performance and compact UHV cells for neutral atom qubit experiments, andMEMS beam scanners for qubit addressing.

Sergei Kurgalin, Sergei Borzunov

Kevin Singh, Shraddha Anand, Andrew Pocklington +2 more

Quantum processing architectures that include multiple qubit modalities offer compelling strategies for high-fidelity operations and readout, quantum error correction, and a path for scaling to large system sizes.Such hybrid architectures have been realized for leading platforms, including superconducting circuits and trapped ions.Recently, a new approach for constructing large, coherent quantum processors has emerged based on arrays of individually trapped neutral atoms.However, these demonstrations have been limited to arrays of a single atomic element where the identical nature of the atoms makes crosstalk-free control and nondemolition readout of a large number of atomic qubits challenging.Here we introduce a dual-element atom array with individual control of single rubidium and cesium atoms.We demonstrate their independent placement in arrays with up to 512 trapping sites and observe negligible crosstalk between the two elements.Furthermore, by continuously reloading one atomic element while maintaining an array of the other, we demonstrate a new continuous operation mode for atom arrays without any off-time.Our results enable avenues for auxiliary-qubit-assisted quantum protocols such as quantum nondemolition measurements and quantum error correction, as well as continuously operating quantum processors and sensors.

Shuanping Du, Zhaofang Bai

Kara Maller, Martin Lichtman, T. Xia +5 more

We present experimental results on two-qubit Rydberg-blockade quantum gates and entanglement in a two-dimensional qubit array. Without postselection against atom loss we achieve a Bell state fidelity of $0.73\ifmmode\pm\else\textpm\fi{}0.05$. The experiments are performed in an array of single Cs atom qubits with a site to site spacing of $3.8\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{m}$. Using the standard protocol for a Rydberg-blockade ${C}_{Z}$ gate together with single qubit operations we create Bell states and measure their fidelity using parity oscillations. We analyze the role of ac Stark shifts that occur when using two-photon Rydberg excitation and show how to tune experimental conditions for optimal gate fidelity.