Curator's Take
This breakthrough addresses one of the most persistent challenges in photonic quantum computing: storing quantum information long enough to perform meaningful operations without losing the delicate quantum states to decoherence. The researchers achieved over one microsecond of storage time for telecom-wavelength photons in a nanophotonic chip, which is remarkable because typical on-chip propagation would destroy the quantum information through losses in a fraction of that time. What makes this particularly exciting is the use of erbium-doped lithium niobate, which operates at standard telecom wavelengths and can be fabricated using existing semiconductor processes, making it highly compatible with current fiber optic infrastructure and scalable manufacturing. This represents a crucial step toward practical quantum networks and distributed quantum computing systems that can reliably store and retrieve quantum information across realistic timescales.
— Mark Eatherly
Summary
Nanophotonic quantum memory is a vital component for scalable quantum information processing in quantum computing, networking, and sensing. Here we store single-photon-level telecom-band optical pulses for more than 1 microsecond using an atomic frequency comb in erbium-doped thin-film lithium niobate, far exceeding what is practically achievable by propagation in even the best nanophotonic devices because of propagation losses. We verify the quantum nature of this storage by demonstrating phase coherence and sub-single-photon noise upon retrieval. We also show the flexibility of our platform by storing up to 20 temporal modes and demonstrating an acceptance bandwidth up to 2.2 GHz. These results establish erbium-doped thin-film lithium niobate as a practical platform for on-chip quantum memory at telecom wavelengths, a key missing element for photonic quantum computing and quantum networking.