A cascaded Random-Access Quantum Memory in a 3D multimode cavity (Part I)

Similar to classical computers, random access quantum memory (RAQM) enhances quantum computing by offering immediate storage and retrieval of data from any randomly selected register. Three-dimensional (3D) cavities are promising memory registers due to their high coherence times. The flute technique facilitates the integration of multiple modes within a single bulk cavity for hardware efficiency. Here, we experimentally demonstrate a multimode RAQM system with a three-layer architecture for crosstalk suppression: Qubit-Processor (2 modes)-Storage (7 modes). The Storage layer serves as high-coherence memory registers, while the Processor layer functions as working memory, facilitating the storage and retrieval of data. The qubit is dispersively coupled to the Processor modes for state preparation and measurement. A tunable coupler provides the SWAP operations between the Storage and Processor layers via parametric modulation. We designed an on-chip fast flux line for 3D cavity systems that enables fast (500 ns), high-fidelity (post-selected fidelity up to 99.9%), and low-crosstalk (below 3 kHz) parametric interactions while preserving high coherence (T1 up to 1.2 ms) for the Storage modes.

This is the first part of a two-part talk. This part will focus on the device setup and essential experimental characterization, including universal single-mode control, full RAQM active reset, and modes’ parametric modulation calibration.