Coherence time and gate fidelities in Rydberg atom quantum simulators and computers are fundamentally limited by the Rydberg state lifetime. Circular Rydberg states are highly promising candidates to overcome this limitation by orders of magnitude, as they can be effectively protected from decay due to their maximum angular momentum. We report the first realization of alkaline-earth circular Rydberg atoms trapped in optical tweezers, which provide unique and novel control possibilities due to the optically active ionic core. Specifically, we demonstrate creation of very high-$n$ ($n=79$) circular states of ${}^{88}\mathrm{Sr}$. We measure lifetimes as long as 2.55 ms at room temperature, which are achieved via cavity-assisted suppression of black-body radiation. We show coherent control of a microwave qubit encoded in circular states of nearby manifolds, and characterize the qubit coherence time via Ramsey and spin-echo spectroscopy. Finally, circular-state tweezer trapping exploiting the ${\mathrm{Sr}}^{+}$ core polarizability is quantified via measurements of the trap-induced light shift on the qubit. Our work opens routes for quantum simulations with circular Rydberg states of divalent atoms, exploiting the emergent toolbox associated with the optically active core ion.

中文翻译：

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光镊中碱土原子的长寿命圆形里德伯量子位

里德堡原子量子模拟器和计算机中的相干时间和门保真度从根本上受到里德堡态寿命的限制。圆里德伯态是非常有希望克服这个数量级限制的候选者，因为它们可以由于其最大角动量而有效地防止衰变。我们报告了首次实现了光镊中捕获的碱土圆形里德伯原子，由于光学活性离子核，它提供了独特且新颖的控制可能性。具体来说，我们展示了非常高的创造$n$（$n=79$）循环状态${}^{88}锶$。我们在室温下测得寿命长达 2.55 毫秒，这是通过空腔辅助抑制黑体辐射实现的。我们展示了对以附近流形的圆形状态编码的微波量子位的相干控制，并通过拉姆齐和自旋回波光谱来表征量子位相干时间。最后，利用环形镊子捕获${锶}^{+}$核心极化率通过测量量子位上陷阱引起的光位移来量化。我们的工作利用与光学活性核心离子相关的新兴工具箱，为二价原子的圆形里德伯态的量子模拟开辟了道路。