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How smooth is quantum complexity?

delete2021-10-28
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OA
AI
V
Vir B. Bulchandani *
S
S. L. Sondhi
DOI:10.1007/JHEP10(2021)230delete
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Abstract

Abstract

En 中文
The quantum complexity of a unitary operator measures the difficulty of its construction from a set of elementary quantum gates. While the notion of quantum complexity was first introduced as a quantum generalization of the classical computational complexity, it has since been argued to hold a fundamental significance in its own right, as a physical quantity analogous to the thermodynamic entropy. In this paper, we present a unified perspective on various notions of quantum complexity, viewed as functions on the space of unitary operators. One striking feature of these functions is that they can exhibit non-smooth and even fractal behaviour. We use ideas from Diophantine approximation theory and sub-Riemannian geometry to rigorously quantify this lack of smoothness. Implications for the physical meaning of quantum complexity are discussed.
Keywords:
AdS-CFT Correspondence
Differential and Algebraic Geometry

Journal

Journal of High Energy Physics cover
Journal of High Energy Physics
IF:
5.5
Papers:
3.9W
Citations:
13.7W

Organization

P
Princeton University
Scholars:
2.1W
Papers: 2.3W
Citations: 5.1W