Neutral atoms trapped in arrays of optical tweezers are a versatile platform for multiple research efforts in quantum information science. In particular, alkaline-earth atoms like Yb offer many advantages including ultralong coherence nuclear spin states for quantum information storage and high-fidelity qubit operations, optical transitions to Rydberg states for generating strong, long-range interactions between atoms, and narrow optical transitions for efficient cooling and metrology. Additionally, optical transitions from the long-lived 3P0 nuclear spin state have frequencies in the telecommunications band making integration with fiber networks and silicon nanophotonics an attractive avenue of exploration for hybrid quantum systems and quantum communication. Finally, these optical tweezer platforms are well suited for investigating the cooperative response of an array of atoms, where the proximity of neighboring atoms fundamentally alters the systems optical response which has implications for quantum information storage. Here I will present efforts to investigate these research avenues using alkaline-earth atoms in optical tweezers.
Neutral atoms trapped in arrays of optical tweezers are a versatile platform for multiple research efforts in quantum information science. In particular, alkaline-earth atoms like Yb offer many advantages including ultralong coherence nuclear spin states for quantum information storage and high-fidelity qubit operations, optical transitions to Rydberg states for generating strong, long-range interactions between atoms, and narrow optical transitions for efficient cooling and metrology. Additionally, optical transitions from the long-lived 3P0 nuclear spin state have frequencies in the telecommunications band making integration with fiber networks and silicon nanophotonics an attractive avenue of exploration for hybrid quantum systems and quantum communication. Finally, these optical tweezer platforms are well suited for investigating the cooperative response of an array of atoms, where the proximity of neighboring atoms fundamentally alters the systems optical response which has implications for quantum information storage. Here I will present efforts to investigate these research avenues using alkaline-earth atoms in optical tweezers.
Neutral atom arrays are a rapidly developing platform for quantum science.Recently, alkaline earth atoms (AEAs) have attracted interest because their unique level structure provides several opportunities for improved performance.In this work, we present the first demonstration of a universal set of quantum gate operations on a nuclear spin qubit in an AEA, using 171 Yb.We implement narrow-line cooling and imaging using a newly discovered magic trapping wavelength at λ ¼ 486.78 nm.We also demonstrate nuclear spin initialization, readout, and single-qubit gates and observe long coherence times [T 1 ≈ 20 s and24ð5Þ s] and a single-qubit operation fidelity F 1Q ¼ 0.99959ð6Þ.We also demonstrate two-qubit entangling gates using the Rydberg blockade, as well as coherent control of these gate operations using light shifts on the Yb þ ion core transition at 369 nm.These results are a significant step toward highly coherent quantum gates in AEA tweezer arrays.
Engineering controllable, strongly interacting many-body quantum systems is at the frontier of quantum simulation and quantum information processing. Arrays of laser-cooled neutral atoms in optical tweezers have emerged as a promising platform because of their flexibility and the potential for strong interactions via Rydberg states. Existing neutral atom array experiments utilize alkali atoms, but alkaline-earth atoms offer many advantages in terms of coherence and control, and also open the door to new applications in precision measurement and time keeping. In this Letter, we present a technique to trap individual alkaline-earth-like ytterbium (Yb) atoms in optical tweezer arrays. The narrow ^{1}S_{0}-^{3}P_{1} intercombination line is used for both cooling and imaging in a magic-wavelength optical tweezer at 532 nm. The low Doppler temperature allows for imaging near the saturation intensity, resulting in a very high atom detection fidelity. We demonstrate the imaging fidelity concretely by observing rare (<1 in 10^{4} images) spontaneous quantum jumps into and out of a metastable state. We also demonstrate stochastic loading of atoms into a two-dimensional, 144-site tweezer array. This platform will enable advances in quantum information processing, quantum simulation, and precision measurement. The demonstrated narrow-line Doppler imaging may also be applied in tweezer arrays or quantum gas microscopes using other atoms with similar transitions, such as erbium and dysprosium.
Neutral atom qubits with Rydberg-mediated interactions are a leading platform for developing large-scale coherent quantum systems. In the majority of experiments to date, the Rydberg states are not trapped by the same potential that confines ground state atoms, resulting in atom loss and constraints on the achievable interaction time. In this Letter, we demonstrate that the Rydberg states of an alkaline earth atom, ytterbium, can be stably trapped by the same red-detuned optical tweezer that also confines the ground state, by leveraging the polarizability of the Yb^{+} ion core. Using the previously unobserved ^{3}S_{1} series, we demonstrate trapped Rydberg atom lifetimes exceeding 100 μs, and observe no evidence of auto- or photoionization from the trap light for these states. We measure a coherence time of T_{2}=59 μs between two Rydberg levels, exceeding the 28 μs lifetime of untrapped Rydberg atoms under the same conditions. These results are promising for extending the interaction time of Rydberg atom arrays for quantum simulation and computing, and are vital to capitalize on the extended Rydberg lifetimes in circular states or cryogenic environments.
Neutral atom qubits with Rydberg-mediated interactions are a leading platform for developing large-scale coherent quantum systems. In the majority of experiments to date, the Rydberg states are not trapped by the same potential that confines ground state atoms, resulting in atom loss and constraints on the achievable interaction time. In this work, we demonstrate that the Rydberg states of an alkaline earth atom, ytterbium, can be stably trapped by the same red-detuned optical tweezer that also confines the ground state, by leveraging the polarizability of the Yb+ ion core. Using the previously unobserved \tripletS series, we demonstrate trapped Rydberg atom lifetimes exceeding 100μs, and observe no evidence of auto- or photo-ionization from the trap light for these states. We measure a coherence time of T2=59μs between two Rydberg levels, exceeding the 28 μs lifetime of untrapped Rydberg atoms under the same conditions. These results are promising for extending the interaction time of Rydberg atom arrays for quantum simulation and computing, and are vital to capitalize on the extended Rydberg lifetimes in circular states or cryogenic environments.
Neutral atom arrays have emerged as a powerful platform for quantum computation, simulation, and metrology.Among them, alkaline-earth-like atoms exhibit distinct advantages, including long coherence time, high-fidelity Rydberg gates, and erasure correction for efficient quantum error correction. However, their scalability has lagged behind that of the alkali atoms. Here, we report 2400 ytterbium-174 atoms trapped in an optical tweezer array with enhanced loading efficiency of 83.5(1)\% via blue-detuned light-assisted collisions. We develop a quantitative model of the collision dynamics and find good agreement between the calculated inelastic collision rates and the experimentally measured loading efficiencies.Notably, the loading efficiency is largely maintained for array sizes ranging from dozens to thousands, exhibiting excellent scalability. We further demonstrate that the enhancement exists robustly across a range of interatomic potentials, suggesting its utility for other atomic species. To establish the capability of the 174Yb arrays toward universal quantum computation, we propose to encode the qubit in the ground-clock state manifold and estimate a 99.9\% two-qubit gate fidelity with experimentally feasible parameters. Our work advances the prospects for realizing large-scale quantum computers using alkaline-earth-like atoms.
We report on the realization of a fast, scalable, and high-fidelity qubit architecture, based on 171 Yb atoms in an optical tweezer array.We demonstrate several attractive properties of this atom for its use as a building block of a quantum information processing platform.Its nuclear spin of 1=2 serves as a long-lived and coherent two-level system, while its rich, alkaline-earth-like electronic structure allows for low-entropy preparation, fast qubit control, and high-fidelity readout.We present a near-deterministic loading protocol, which allows us to fill a 10 × 10 tweezer array with 92.73(8)% efficiency and a single tweezer with 96.0(1.4)%efficiency.In the future, this loading protocol will enable efficient and uniform loading of target arrays with high probability, an essential step in quantum simulation and information applications.Employing a robust optical approach, we perform submicrosecond qubit rotations and characterize their fidelity through randomized benchmarking, yielding 5.2ð5Þ × 10 -3 error per Clifford gate.For quantum memory applications, we measure the coherence of our qubits with T Ã 2 ¼ 3.7ð4Þ s and T 2 ¼ 7.9ð4Þ s, many orders of magnitude longer than our qubit rotation pulses.We measure spin depolarization times on the order of tens of seconds and find that this can be increased to the 100 s scale through the application of a several-gauss magnetic field.Finally, we use 3D Raman-sideband cooling to bring the atoms near their motional ground state, which will be central to future implementations of two-qubit gates that benefit from low motional entropy.