A no-go result for pure state synthesis in the DQC1 model

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1. Verfasser: Stier, Zachary
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Veröffentlicht: 2024
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author Stier, Zachary
author_facet Stier, Zachary
contents We study the problem of state synthesis in the DQC1 (One Clean Qubit) model of quantum computation, which provides a single pure qubit and $n$ maximally mixed qubits, and after applying any quantum circuit some subset of the qubits are measured or discarded. In the case of discarding, we show that it is impossible to prepare additional pure qubits, and that it is impossible to prepare very low-temperature Gibbs states on additional qubits. In the case of measurements, we show that the probability of synthesizing $m$ additional qubits is bounded by $2^{1-m}$, and that the probability of preparing low-temperature Gibbs states is bounded by $2^{2-m}$. As a consequence, we give a lower-bound the runtime of a recently studied class of repeated interaction quantum algorithms. The techniques used study states and circuits at the level of entries of their respective density and unitary matrices.
format Preprint
id arxiv_https___arxiv_org_abs_2404_04198
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A no-go result for pure state synthesis in the DQC1 model
Stier, Zachary
Quantum Physics
We study the problem of state synthesis in the DQC1 (One Clean Qubit) model of quantum computation, which provides a single pure qubit and $n$ maximally mixed qubits, and after applying any quantum circuit some subset of the qubits are measured or discarded. In the case of discarding, we show that it is impossible to prepare additional pure qubits, and that it is impossible to prepare very low-temperature Gibbs states on additional qubits. In the case of measurements, we show that the probability of synthesizing $m$ additional qubits is bounded by $2^{1-m}$, and that the probability of preparing low-temperature Gibbs states is bounded by $2^{2-m}$. As a consequence, we give a lower-bound the runtime of a recently studied class of repeated interaction quantum algorithms. The techniques used study states and circuits at the level of entries of their respective density and unitary matrices.
title A no-go result for pure state synthesis in the DQC1 model
topic Quantum Physics
url https://arxiv.org/abs/2404.04198