Extended Rydberg Lifetimes in a Cryogenic Atom Array

Neutral atoms in optical tweezer arrays are a promising platform for large-scale quantum computing. Two-qubit gate fidelities are increasingly limited by the ground-Rydberg T₁ lifetime. We report on the realization of atom arrays in a cryogenic blackbody radiation environment. Combined with a single-photon Rydberg excitation scheme, this allows us to achieve long ground-Rydberg qubit T₁, about 400 µs for the 55P_3/2 Rydberg state, a factor of 3.3 longer than the T₁ at room temperature. This corresponds to an effective blackbody-radiation (BBR) temperature of ~10 K and more than an order-of-magnitude suppression of BBR-induced decay. Compared with two-photon schemes, single-photon Rydberg excitation also exhibits substantially reduced light shifts, making it less susceptible to decoherence from laser intensity fluctuations. These results pave the path towards further improvements in neutral-atom two-qubit gate fidelities. The strong suppression of BBR-induced decay also benefits quantum simulation and metrology applications based on Rydberg dressing.