Faulty towers: recovering a functioning quantum random access memory in the presence of defective routers
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arXiv
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| Auteurs principaux: | , , , , |
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866909402980679680 |
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| author | Weiss, D. K. Xu, Shifan Puri, Shruti Ding, Yongshan Girvin, S. M. |
| author_facet | Weiss, D. K. Xu, Shifan Puri, Shruti Ding, Yongshan Girvin, S. M. |
| contents | Proposals for quantum random access memory (QRAM) generally have a binary-tree structure, and thus require hardware that is exponential in the depth of the QRAM. For solid-state based devices, a fabrication yield that is less than $100\%$ implies that certain addresses at the bottom of the tree become inaccessible if a router in the unique path to that address is faulty. We discuss how to recover a functioning QRAM in the presence of faulty routers. We present the \texttt{IterativeRepair} algorithm, which constructs QRAMs layer by layer until the desired depth is reached. This algorithm utilizes ancilla flag qubits which reroute queries to faulty routers. We present a classical algorithm \texttt{FlagQubitMinimization} that attempts to minimize the required number of such ancilla. For a router failure rate of $1\%$ and a QRAM of depth $n=13$, we expect that on average 430 addresses need repair: we require only 1.5 ancilla flag qubits on average to perform this rerouting. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_15612 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Faulty towers: recovering a functioning quantum random access memory in the presence of defective routers Weiss, D. K. Xu, Shifan Puri, Shruti Ding, Yongshan Girvin, S. M. Quantum Physics Proposals for quantum random access memory (QRAM) generally have a binary-tree structure, and thus require hardware that is exponential in the depth of the QRAM. For solid-state based devices, a fabrication yield that is less than $100\%$ implies that certain addresses at the bottom of the tree become inaccessible if a router in the unique path to that address is faulty. We discuss how to recover a functioning QRAM in the presence of faulty routers. We present the \texttt{IterativeRepair} algorithm, which constructs QRAMs layer by layer until the desired depth is reached. This algorithm utilizes ancilla flag qubits which reroute queries to faulty routers. We present a classical algorithm \texttt{FlagQubitMinimization} that attempts to minimize the required number of such ancilla. For a router failure rate of $1\%$ and a QRAM of depth $n=13$, we expect that on average 430 addresses need repair: we require only 1.5 ancilla flag qubits on average to perform this rerouting. |
| title | Faulty towers: recovering a functioning quantum random access memory in the presence of defective routers |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2411.15612 |