Dual-unitary shadow tomography

Fuente: arXiv
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Main Authors: Akhtar, Ahmed A., Anand, Namit, Marshall, Jeffrey, You, Yi-Zhuang
Format: Preprint
Published: 2024
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author Akhtar, Ahmed A.
Anand, Namit
Marshall, Jeffrey
You, Yi-Zhuang
author_facet Akhtar, Ahmed A.
Anand, Namit
Marshall, Jeffrey
You, Yi-Zhuang
contents We introduce ``dual-unitary shadow tomography'' (DUST), a classical shadow tomography protocol based on dual-unitary brick-wall circuits. To quantify the performance of DUST, we study operator spreading and Pauli weight dynamics in one-dimensional qubit systems, evolved by random two-local dual-unitary gates arranged in a brick-wall structure, ending with a measurement layer. We do this by deriving general constraints on the Pauli weight transfer matrix and specializing to the case of dual-unitarity. Remarkably, we find that operator spreading in these circuits have a rich structure resembling that of relativistic quantum field theories, with massless chiral excitations that can decay or fuse into each other, which we call left- or right-movers. We develop a mean-field description of the Pauli weight in terms of $ρ(x,t)$, which represents the probability of having nontrivial support at site $x$ and depth $t$ starting from a fixed weight distribution. We develop an equation of state for $ρ(x,t)$ and simulate it numerically using Monte Carlo simulations. For the task of predicting operators with (nearly) full support, we show that DUST outperforms brick-wall Clifford shadows of equal depth. This advantage is further pronounced for small system sizes and our results are generally robust to finite-size effects.
format Preprint
id arxiv_https___arxiv_org_abs_2404_01068
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Dual-unitary shadow tomography
Akhtar, Ahmed A.
Anand, Namit
Marshall, Jeffrey
You, Yi-Zhuang
Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Mathematical Physics
We introduce ``dual-unitary shadow tomography'' (DUST), a classical shadow tomography protocol based on dual-unitary brick-wall circuits. To quantify the performance of DUST, we study operator spreading and Pauli weight dynamics in one-dimensional qubit systems, evolved by random two-local dual-unitary gates arranged in a brick-wall structure, ending with a measurement layer. We do this by deriving general constraints on the Pauli weight transfer matrix and specializing to the case of dual-unitarity. Remarkably, we find that operator spreading in these circuits have a rich structure resembling that of relativistic quantum field theories, with massless chiral excitations that can decay or fuse into each other, which we call left- or right-movers. We develop a mean-field description of the Pauli weight in terms of $ρ(x,t)$, which represents the probability of having nontrivial support at site $x$ and depth $t$ starting from a fixed weight distribution. We develop an equation of state for $ρ(x,t)$ and simulate it numerically using Monte Carlo simulations. For the task of predicting operators with (nearly) full support, we show that DUST outperforms brick-wall Clifford shadows of equal depth. This advantage is further pronounced for small system sizes and our results are generally robust to finite-size effects.
title Dual-unitary shadow tomography
topic Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2404.01068