QSE Quantum Seminar: High-fidelity entanglement and coherent multi-qubit mapping in an atom array, Alex Baumgartner

Please join us for the QSE Center Quantum Seminar with Alex Baumgartner from University of Colorado Boulder who will give the talk "High-fidelity entanglement and coherent multi-qubit mapping in an atom array" on Thursday January 8 from 12pm to 1:30pm.
Location: CM 1 120

Pizzas will be available at 12:00. All PhDs, postdocs, students, group leaders, and PIs are welcome to join us.

TITLE: "High-fidelity entanglement and coherent multi-qubit mapping in an atom array"

ABSTRACT:
Neutral atoms in optical tweezer arrays possess broad applicability for quantum information science, in computing, simulation, and metrology. Among atomic species, Ytterbium-171 is unique as it hosts multiple qubits, each of which is impactful for these distinct applications. Consequently, this atom is an ideal candidate to bridge multiple disciplines, which, more broadly, has been an increasingly effective strategy within the field of quantum science. Realizing the full potential of this synergy requires high-fidelity generation and transfer of many-particle entanglement between these distinct qubit degrees of freedom, and thus between these distinct applications. Here we demonstrate the creation and coherent mapping of entangled quantum states across multiple qubits in Ytterbium-171 tweezer arrays. We map entangled states onto the optical clock qubit from the nuclear spin qubit or the Rydberg qubit. We coherently transfer up to 20 atoms of a Z2-ordered Greenberger-Horne-Zeilinger (GHZ) state from the interacting Rydberg manifold to the metastable nuclear spin manifold. The many-body state is generated via a novel disorder-robust pulse in a two-dimensional ladder geometry. We further find that clock-qubit-based spin detection applied to Rydberg and nuclear spin qubits facilitates atom-loss-detectable qubit measurements and >90% Rydberg decay detection. This enables mid-circuit and delayed erasure detection, yielding an error-detected two-qubit gate fidelity of 99.78(4)% in the metastable qubits. This error detection also enables Rydberg qubit evolution with an effective lifetime of 1.2(2) ms, enhancing the fidelity of the observed many-body dynamics. These results establish a versatile architecture that advances multiple fields of quantum information science while also establishing bridges between them. 

BIO: 
Alex Baumgartner is post-doc at JILA and university of Colorado at Boulder, in the group of Adam Kaufman. He did his PhD at ETHZ in 2024 on dissipation, topology and subradiance in cavity quantum electrodynamics.