Multimode and Random-Access Optical Quantum Memory via Adiabatic Phase Imprinting

A photonic quantum memory that can store multiple qubits and later recall any randomly chosen subset is essential for large-scale quantum networking and computing. This capability, similar to random-access memory in classical computers, has been difficult to achieve due to the lack of a versatile random-access mechanism and the limited multi-mode storage capacity of existing quantum memory protocols. One promising route uses photon-echo protocols, which apply optical rephasing pulses to selectively read out frequency-multiplexed photonic qubits within a broadened optical transition. Here we advance a photon-echo-based quantum memory protocol using linearly swept adiabatic rephasing pulses, which imprint phase shifts to suppress unwanted echoes. Using the optical transitions of a 171Yb3+:Y2SiO5 crystal, we demonstrate storage and retrieval of multiple complex spectro-temporal photonic modes and achieve random-access memory across eight distinct spectral modes. We show enhanced mode-mapping versatility while substantially lowering the required rephasing pulse intensity, providing a more efficient and reliable approach for high-fidelity qubit storage and retrieval. Scalable quantum networks require memories that store photonic qubits while allowing selective access to individual states, a capability not currently available. A chirped-pulse phase-encoding approach provides random access to spectro-temporal-multiplexed information, enabling storage and retrieval across eight spectral modes with lower rephasing pulse intensity.