Scalable local control over gate operations is an outstanding challenge in the field of quantum computing and programmable quantum simulation with Rydberg-atom arrays. One approach is to use a global ...field to excite atoms to the Rydberg state and tune individual atoms in and out of resonance via local light shifts. In this work, we point out that photon-scattering errors from light shifts can be significantly reduced if the light shift is applied to the Rydberg state instead of the ground state, which can be realized in Rydberg states of alkaline-earth atoms using optical transitions in the ion core. As a proof of concept, we experimentally demonstrate global control of Rydberg excitations in an Yb optical-tweezer array via light shifts induced by a laser tuned near the Yb^{+}6s→6p_{1/2} transition. We also perform detailed spectroscopy of the induced light shift and scattering rates of the 6sns^{3}S_{1} Rydberg states and reveal the existence of satellite lines where losses from autoionization are strongly suppressed. This work can be readily extended to implement local gate operations in Rydberg-atom arrays.
Integrating nanophotonics and cold atoms has drawn increasing interest in recent years due to diverse applications in quantum information science and the exploration of quantum many‐body physics. For ...example, dispersion‐engineered photonic crystal waveguides (PCWs) permit not only stable trapping and probing of ultracold neutral atoms via interactions with guided‐mode light, but also the possibility to explore the physics of strong, photon‐mediated interactions between atoms, as well as atom‐mediated interactions between photons. While diverse theoretical opportunities involving atoms and photons in 1D and 2D nanophotonic lattices have been analyzed, a grand challenge remains the experimental integration of PCWs with ultracold atoms. Here, an advanced apparatus that overcomes several significant barriers to current experimental progress is described, with the goal of achieving strong quantum interactions of light and matter by way of single‐atom tweezer arrays strongly coupled to photons in 1D and 2D PCWs. Principal technical advances relate to efficient free‐space coupling of light to and from guided modes of PCWs, silicate bonding of silicon chips within small glass vacuum cells, and deterministic, mechanical delivery of single‐atom tweezer arrays to the near fields of photonic crystal waveguides.
Integrating nanophotonics and cold atoms is drawing growing interest due to diverse applications in quantum information science and quantum many‐body physics. However, laboratory progress has lagged theory due to grand challenges in combining ultracold atoms and nanophotonic devices. Here, an advanced apparatus is described that overcomes several significant barriers toward the experimental integration of nano‐photonics with single‐atom tweezer arrays.
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=486.78 nm. We also demonstrate nuclear spin initialization, readout, and single-qubit gates and observe long coherence times T_{1}≈20 s and T_{2}^{*}=1.24(5) s and a single-qubit operation fidelity F_{1Q}=0.99959(6). 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^{+} ion core transition at 369 nm. These results are a significant step toward highly coherent quantum gates in AEA tweezer arrays.
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, usingYb171. We implement narrow-line cooling and imaging using a newly discovered magic trapping wavelength atλ=486.78nm. We also demonstrate nuclear spin initialization, readout, and single-qubit gates and observe long coherence times T1≈20sandT2*=1.24(5)s and a single-qubit operation fidelityF1Q=0.99959(6). We also demonstrate two-qubit entangling gates using the Rydberg blockade, as well as coherent control of these gate operations using light shifts on theYb+ion core transition at 369 nm. These results are a significant step toward highly coherent quantum gates in AEA tweezer arrays.
We present multichannel quantum defect (MQDT) models for highly excited \(^{174}\)Yb and \(^{171}\)Yb Rydberg states with \(L \leq 2\). The models are developed using a combination of existing ...literature data and new, high-precision laser and microwave spectroscopy in an atomic beam, and validated by detailed comparison with experimentally measured Stark shifts and magnetic moments. We then use these models to compute interaction potentials between two Yb atoms, and find excellent agreement with direct measurements in an optical tweezer array. From the computed interaction potential, we identify an anomalous F\"orster resonance that likely degraded the fidelity of previous entangling gates in \(^{171}\)Yb using \(F=3/2\) Rydberg states. We then identify a more suitable \(F=1/2\) state, and achieve a state-of-the-art controlled-Z gate fidelity of \(\mathcal{F}=0.994(1)\), with the remaining error fully explained by known sources. This work establishes a solid foundation for the continued development quantum computing, simulation and entanglement-enhanced metrology with Yb neutral atom arrays.
Neutral atom arrays are a rapidly developing platform for quantum science. In this work, we demonstrate a universal set of quantum gate operations on a new type of neutral atom qubit: a nuclear spin ...in an alkaline earth-like atom (AEA), \(^{171}\)Yb. We present techniques for cooling, trapping and imaging using a newly discovered magic trapping wavelength at \(\lambda = 486.78\) nm. We implement qubit initialization, readout, and single-qubit gates, and observe long qubit lifetimes, \(T_1 \approx 20\) s and \(T^*_2 = 1.24(5)\) s, and a single-qubit operation fidelity \(\mathcal{F}_{1Q} = 0.99959(6)\). 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\(^+\) ion core transition at 369 nm. These results are a significant step towards highly coherent quantum gates in AEA tweezer arrays.
The development of scalable, high-fidelity qubits is a key challenge in quantum information science. Neutral atom qubits have progressed rapidly in recent years, demonstrating programmable processors ...and quantum simulators with scaling to hundreds of atoms. Exploring new atomic species, such as alkaline earth atoms, or combining multiple species can provide new paths to improving coherence, control and scalability. For example, for eventual application in quantum error correction, it is advantageous to realize qubits with structured error models, such as biased Pauli errors or conversion of errors into detectable erasures. In this work, we demonstrate a new neutral atom qubit, using the nuclear spin of a long-lived metastable state in \({}^{171}\)Yb. The long coherence time and fast excitation to the Rydberg state allow one- and two-qubit gates with fidelities of 0.9990(1) and 0.980(1), respectively. Importantly, a significant fraction of all gate errors result in decays out of the qubit subspace, to the ground state. By performing fast, mid-circuit detection of these errors, we convert them into erasure errors; during detection, the induced error probability on qubits remaining in the computational space is less than \(10^{-5}\). This work establishes metastable \({}^{171}\)Yb as a promising platform for realizing fault-tolerant quantum computing.
Scalable, local control over gate operations is an outstanding challenge in the field of quantum computing and programmable quantum simulation with Rydberg atom arrays. One approach is to use a ...global field to excite atoms to the Rydberg state, and tune individual atoms in and out of resonance via local light shifts. In this work, we point out that photon scattering errors from light shifts can be significantly reduced if the light shift is applied to the Rydberg state instead of the ground state, which can be realized in Rydberg states of alkaline earth atoms using optical transitions in the ion core. As a proof-of-concept, we experimentally demonstrate global control of Rydberg excitations in a Yb optical tweezer array via light shifts induced by a laser tuned near the Yb\(^+\) \(6s\rightarrow6p_{1/2}\) transition. We also perform detailed spectroscopy of the induced light shift and scattering rates of the \(6sns\) \(^3\)S\(_1\) Rydberg states and reveal the existence of satellite lines where losses from autoionization are strongly suppressed. This work can be readily extended to implement local gate operations in Rydberg atom arrays.
PDF