Experimental realization of Shor’s quantum factoring algorithm using qubit recycling

Enrique Martin-Lopez, Anthony Laing, Thomas M Lawson, Roberto Alvarez, Xiao-Qi Zhou, Jeremy L O'Brien

Research output: Contribution to journalArticle (Academic Journal)peer-review

181 Citations (Scopus)


Quantum computational algorithms exploit quantum mech- anics to solve problems exponentially faster than the best classical algorithms. Shor’s quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realize a quantum computer. However, due to the substantial resource requirement, to date there have been only four small-scale demonstrations. Here, we address this resource demand and demonstrate a scalable version of Shor’s algorithm in which the n-qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one-third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N=21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor’s algorithm by harnessing scalable resource reductions applicable to all physical architectures.
Original languageEnglish
Pages (from-to)773-776
Number of pages4
JournalNature Photonics
Issue number11
Early online date21 Oct 2012
Publication statusPublished - Nov 2012

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    O'Brien, J. L.


    Project: Research

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