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Main Authors: Li, Lu, Bu, Kaifeng, Koh, Dax Enshan, Jaffe, Arthur, Lloyd, Seth
Format: Preprint
Published: 2022
Subjects:
Online Access:https://arxiv.org/abs/2208.06306
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author Li, Lu
Bu, Kaifeng
Koh, Dax Enshan
Jaffe, Arthur
Lloyd, Seth
author_facet Li, Lu
Bu, Kaifeng
Koh, Dax Enshan
Jaffe, Arthur
Lloyd, Seth
contents Given a unitary transformation, what is the size of the smallest quantum circuit that implements it? This quantity, known as the quantum circuit complexity, is a fundamental property of quantum evolutions that has widespread applications in many fields, including quantum computation, quantum field theory, and black hole physics. In this letter, we obtain a new lower bound for the quantum circuit complexity in terms of a novel complexity measure that we propose for quantum circuits, which we call the quantum Wasserstein complexity. Our proposed measure is based on the quantum Wasserstein distance of order one (also called the quantum earth mover's distance), a metric on the space of quantum states. We also prove several fundamental and important properties of our new complexity measure, which stand to be of independent interest. Finally, we show that our new measure also provides a lower bound for the experimental cost of implementing quantum circuits, which implies a quantum limit on converting quantum resources to computational resources. Our results provide novel applications of the quantum Wasserstein distance and pave the way for a deeper understanding of the resources needed to implement a quantum computation.
format Preprint
id arxiv_https___arxiv_org_abs_2208_06306
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Wasserstein Complexity of Quantum Circuits
Li, Lu
Bu, Kaifeng
Koh, Dax Enshan
Jaffe, Arthur
Lloyd, Seth
Quantum Physics
Computational Complexity
High Energy Physics - Theory
Mathematical Physics
Given a unitary transformation, what is the size of the smallest quantum circuit that implements it? This quantity, known as the quantum circuit complexity, is a fundamental property of quantum evolutions that has widespread applications in many fields, including quantum computation, quantum field theory, and black hole physics. In this letter, we obtain a new lower bound for the quantum circuit complexity in terms of a novel complexity measure that we propose for quantum circuits, which we call the quantum Wasserstein complexity. Our proposed measure is based on the quantum Wasserstein distance of order one (also called the quantum earth mover's distance), a metric on the space of quantum states. We also prove several fundamental and important properties of our new complexity measure, which stand to be of independent interest. Finally, we show that our new measure also provides a lower bound for the experimental cost of implementing quantum circuits, which implies a quantum limit on converting quantum resources to computational resources. Our results provide novel applications of the quantum Wasserstein distance and pave the way for a deeper understanding of the resources needed to implement a quantum computation.
title Wasserstein Complexity of Quantum Circuits
topic Quantum Physics
Computational Complexity
High Energy Physics - Theory
Mathematical Physics
url https://arxiv.org/abs/2208.06306