Speed limits for quantum gates in multiqubit systems

S. Ashhab, P. C. De Groot, Franco Nori

Research output: Contribution to journalArticle

38 Citations (Scopus)


We use analytical and numerical calculations to obtain speed limits for various unitary quantum operations in multiqubit systems under typical experimental conditions. The operations that we consider include single-, two-, and three-qubit gates, as well as quantum-state transfer in a chain of qubits. We find in particular that simple methods for implementing two-qubit gates generally provide the fastest possible implementations of these gates. We also find that the three-qubit Toffoli gate time varies greatly depending on the type of interactions and the system's geometry, taking only slightly longer than a two-qubit controlled-not (cnot) gate for a triangle geometry. The speed limit for quantum-state transfer across a qubit chain is set by the maximum spin-wave speed in the chain.

Original languageEnglish
Article number052327
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
Publication statusPublished - 29 May 2012


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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