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Efficient Networks for Quantum Factoring

David Beckman·Amalavoyal N. Chari·Srikrishna Devabhaktuni·John Preskill
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Abstract

We consider how to optimize memory use and computation time in operating a quantum computer. In particular, we estimate the number of memory qubits and the number of operations required to perform factorization, using the algorithm suggested by Shor. A $K$-bit number can be factored in time of order $K^3$ using a machine capable of storing $5K+1$ qubits. Evaluation of the modular exponential function (the bottleneck of Shor's algorithm) could be achieved with about $72 K^3$ elementary quantum gates; implementation using a linear ion trap would require about $396 K^3$ laser pulses. A proof-of-principle demonstration of quantum factoring (factorization of 15) could be performed with only 6 trapped ions and 38 laser pulses. Though the ion trap may never be a useful computer, it will be a powerful device for exploring experimentally the properties of entangled quantum states.

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David Beckman, Amalavoyal N. Chari, Srikrishna Devabhaktuni, John Preskill. 1996-02-21. Efficient Networks for Quantum Factoring. https://doi.org/10.1103/physreva.54.1034

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