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A bucket-brigade quantum random access memory
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DOI：10.1038/s41567-026-03218-2.png)
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Abstract
En 中文
Quantum random access memory (QRAM) enables efficient access to classical data for quantum computers and is a prerequisite for many quantum algorithms in achieving quantum speed-up. Despite various proposals, there have not been many experimental realizations of QRAM. Here we use a superconducting quantum processor to implement a circuit-based bucket-brigade QRAM, which uses a binary tree of quantum routers to enable efficient addressing of the stored information. To facilitate the experimental implementation, we introduce an efficient gate decomposition scheme for quantum routers, which effectively reduces the depth of the QRAM circuit compared with the conventional controlled-SWAP implementation. We further propose an error mitigation method to improve the query fidelity of the QRAM. With these techniques, we are able to experimentally implement the QRAM architectures for addressing four and eight classical bits, achieving query fidelities up to 0.809 ± 0.025 and 0.604 ± 0.005, respectively. Additionally, we study the error propagation mechanism and the scalability of our QRAM implementation, which provides experimental evidence for the noise resilience of the bucket-brigade architecture. Our results highlight the potential of superconducting quantum processors for realizing a scalable QRAM architecture. Random access memory has multiple data registers and uses addresses to specify which register should be read or modified. Now a quantum random access memory has been demonstrated that uses quantum addresses to return data in superposition.
Keywords:
Physics
Quantum physics
general
Theoretical
Mathematical and Computational Physics
Classical and Continuum Physics
Atomic
Molecular
Optical and Plasma Physics
Condensed Matter Physics
Complex Systems
Journal
IF:
18.4
Papers:
6.7K
Citations:
5.7W