The Hadamard gate cannot be replaced by a resource state in universal quantum computation

Fuente: arXiv
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Main Authors: Jones, Benjamin D. M., Linden, Noah, Skrzypczyk, Paul
Format: Preprint
Published: 2023
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author Jones, Benjamin D. M.
Linden, Noah
Skrzypczyk, Paul
author_facet Jones, Benjamin D. M.
Linden, Noah
Skrzypczyk, Paul
contents We consider models of quantum computation that involve operations performed on some fixed resourceful quantum state. Examples that fit this paradigm include magic state injection and measurement-based approaches. We introduce a framework that incorporates both of these cases and focus on the role of coherence (or superposition) in this context, as exemplified through the Hadamard gate. We prove that given access to incoherent unitaries (those that are unable to generate superposition from computational basis states, e.g. CNOT, diagonal gates), classical control, computational basis measurements, and any resourceful ancillary state (of arbitrary dimension), it is not possible to implement any coherent unitary (e.g. Hadamard) exactly with non-zero probability. We also consider the approximate case by providing lower bounds for the induced trace distance between the above operations and $n$ Hadamard gates. To demonstrate the stability of this result, this is then extended to a similar no-go result for the case of using $k$ Hadamard gates to exactly implement $n>k$ Hadamard gates.
format Preprint
id arxiv_https___arxiv_org_abs_2312_03515
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Hadamard gate cannot be replaced by a resource state in universal quantum computation
Jones, Benjamin D. M.
Linden, Noah
Skrzypczyk, Paul
Quantum Physics
We consider models of quantum computation that involve operations performed on some fixed resourceful quantum state. Examples that fit this paradigm include magic state injection and measurement-based approaches. We introduce a framework that incorporates both of these cases and focus on the role of coherence (or superposition) in this context, as exemplified through the Hadamard gate. We prove that given access to incoherent unitaries (those that are unable to generate superposition from computational basis states, e.g. CNOT, diagonal gates), classical control, computational basis measurements, and any resourceful ancillary state (of arbitrary dimension), it is not possible to implement any coherent unitary (e.g. Hadamard) exactly with non-zero probability. We also consider the approximate case by providing lower bounds for the induced trace distance between the above operations and $n$ Hadamard gates. To demonstrate the stability of this result, this is then extended to a similar no-go result for the case of using $k$ Hadamard gates to exactly implement $n>k$ Hadamard gates.
title The Hadamard gate cannot be replaced by a resource state in universal quantum computation
topic Quantum Physics
url https://arxiv.org/abs/2312.03515