Mediated gates between spin qubits

Jianjia Fei, Dong Zhou, Yun-Pil Shim, Sangchul Oh, Xuedong Hu, and Mark Friesen
Phys. Rev. A 86, 062328 – Published 26 December 2012

Abstract

In a typical quantum circuit, nonlocal quantum gates are applied to nonproximal qubits. If the underlying physical interactions are short-range (e.g., exchange interactions between spins), intermediate swap operations must be introduced, thus increasing the circuit depth. Here we develop a class of “mediated” gates for spin qubits, which act on nonproximal spins via intermediate ancilla qubits. At the end of the operation, the ancillae return to their initial states. We show how these mediated gates can be used (1) to generate arbitrary quantum states and (2) to construct arbitrary quantum gates. We provide some explicit examples of circuits that generate common states [e.g., Bell, Greenberger-Horne-Zeilinger (GHZ), W, and cluster states] and gates (e.g., swap, swap, cnot, and Toffoli gates). We show that the depths of these circuits are often shorter than those of conventional swap-based circuits. We also provide an explicit experimental proposal for implementing a mediated gate in a triple-quantum-dot system.

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  • Received 26 July 2012

DOI:https://doi.org/10.1103/PhysRevA.86.062328

©2012 American Physical Society

Authors & Affiliations

Jianjia Fei1,*, Dong Zhou2, Yun-Pil Shim1, Sangchul Oh3, Xuedong Hu3, and Mark Friesen1

  • 1Department of Physics, University of Wisconsin—Madison, Madison, Wisconsin 53706, USA
  • 2Department of Physics, Yale University, New Haven, Connecticut 06520, USA
  • 3Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA

  • *jfei@wisc.edu

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Vol. 86, Iss. 6 — December 2012

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