Wire recycling for quantum circuit optimization

Alexandru Paler, Robert Wille, and Simon J. Devitt
Phys. Rev. A 94, 042337 – Published 24 October 2016

Abstract

Quantum information processing is expressed using quantum bits (qubits) and quantum gates which are arranged in terms of quantum circuits. Here, each qubit is associated with a quantum circuit wire which is used to conduct the desired operations. Most of the existing quantum circuits allocate a single quantum circuit wire for each qubit and hence introduce significant overhead. In fact, qubits are usually not needed during the entire computation, only between their initialization and measurement. Before and after that, corresponding wires may be used by other qubits. In this work, we propose a solution which exploits this fact in order to optimize the design of quantum circuits with respect to the required wires. To this end, we introduce a representation of the lifetimes of all qubits which is used to analyze the respective need for wires. Based on this analysis, a method is proposed which “recycles” the available wires and, as a result, reduces the size of the resulting circuit. Numerical tests based on established reversible and fault-tolerant quantum circuits confirm that the proposed solution reduces the number of wires by more than 90% compared to unoptimized quantum circuits.

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  • Received 3 September 2016

DOI:https://doi.org/10.1103/PhysRevA.94.042337

©2016 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Quantum Information, Science & Technology

Authors & Affiliations

Alexandru Paler and Robert Wille

  • Johannes Kepler University Linz, Altenberger Strasse 69, 4070 Linz, Austria

Simon J. Devitt

  • Center for Emergent Matter Sciences, Riken, Saitama 351-0198, Japan

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Issue

Vol. 94, Iss. 4 — October 2016

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