Rydberg atoms, with their enormous electronic orbitals, exhibit dipole–dipole interactions reaching the gigahertz range at a distance of a micrometre, making them a prominent contender for realizing ultrafast quantum operations. However, such strong interactions between two single atoms have so far never been harnessed due to the stringent requirements on the fluctuation of the atom positions and the necessary excitation strength. Here we introduce novel techniques to explore this regime. First, we trap and cool atoms to the motional quantum ground state of holographic optical tweezers, which allows control of the inter-atomic distance down to 1.5 μm with a quantum-limited precision of 30 nm. We then use ultrashort laser pulses to excite a pair of these nearby atoms to a Rydberg state simultaneously, far beyond the Rydberg blockade regime, and perform Ramsey interferometry with attosecond precision. This allows us to induce and track an ultrafast interaction-driven energy exchange completed on nanosecond timescales—two orders of magnitude faster than in any other Rydberg experiments in the tweezers platform so far. This ultrafast coherent dynamics gives rise to a conditional phase, which is the key resource for a quantum gate, opening the path for quantum simulation and computation operating at the speed limit set by dipole–dipole interactions with this ultrafast Rydberg platform.

里德堡原子具有巨大的电子轨道，在微米距离处表现出达到千兆赫兹范围的偶极-偶极相互作用，使其成为实现超快量子操作的重要竞争者。然而，由于对原子位置的波动和必要的激发强度的严格要求，迄今为止从未利用过两个单原子之间如此强的相互作用。在这里，我们介绍了探索这种制度的新技术。首先，我们将原子捕获并冷却到全息光镊的运动量子基态，这允许将原子间距离控制到 1.5 μm，量子限制精度为 30 nm。然后，我们使用超短激光脉冲将一对附近的原子同时激发到里德堡状态，远远超出里德堡封锁状态，并以阿秒精度执行 Ramsey 干涉测量。这使我们能够诱导和跟踪在纳秒时间尺度上完成的超快相互作用驱动的能量交换——比迄今为止在镊子平台上的任何其他 Rydberg 实验快两个数量级。这种超快相干动力学产生了条件相位，这是量子门的关键资源，为量子模拟和计算开辟了道路，该路径以偶极-偶极相互作用所设定的速度极限与这个超快的里德堡平台进行。