Pseudorandom and Pseudoentangled States from Subset States

Fuente: arXiv
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Autori principali: Jeronimo, Fernando Granha, Magrafta, Nir, Wu, Pei
Natura: Preprint
Pubblicazione: 2023
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author Jeronimo, Fernando Granha
Magrafta, Nir
Wu, Pei
author_facet Jeronimo, Fernando Granha
Magrafta, Nir
Wu, Pei
contents Pseudorandom states (PRS) are an important primitive in quantum cryptography. In this paper, we show that subset states can be used to construct PRSs. A subset state with respect to $S$, a subset of the computational basis, is \[ \frac{1}{\sqrt{|S|}}\sum_{i\in S} |i\rangle. \] As a technical centerpiece, we show that for any fixed subset size $|S|=s$ such that $s = 2^n/ω(\mathrm{poly}(n))$ and $s=ω(\mathrm{poly}(n))$, where $n$ is the number of qubits, a random subset state is information-theoretically indistinguishable from a Haar random state even provided with polynomially many copies. This range of parameter is tight. Our work resolves a conjecture by Ji, Liu and Song. Since subset states of small size have small entanglement across all cuts, this construction also illustrates a pseudoentanglement phenomenon.
format Preprint
id arxiv_https___arxiv_org_abs_2312_15285
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Pseudorandom and Pseudoentangled States from Subset States
Jeronimo, Fernando Granha
Magrafta, Nir
Wu, Pei
Quantum Physics
Computational Complexity
Cryptography and Security
Pseudorandom states (PRS) are an important primitive in quantum cryptography. In this paper, we show that subset states can be used to construct PRSs. A subset state with respect to $S$, a subset of the computational basis, is \[ \frac{1}{\sqrt{|S|}}\sum_{i\in S} |i\rangle. \] As a technical centerpiece, we show that for any fixed subset size $|S|=s$ such that $s = 2^n/ω(\mathrm{poly}(n))$ and $s=ω(\mathrm{poly}(n))$, where $n$ is the number of qubits, a random subset state is information-theoretically indistinguishable from a Haar random state even provided with polynomially many copies. This range of parameter is tight. Our work resolves a conjecture by Ji, Liu and Song. Since subset states of small size have small entanglement across all cuts, this construction also illustrates a pseudoentanglement phenomenon.
title Pseudorandom and Pseudoentangled States from Subset States
topic Quantum Physics
Computational Complexity
Cryptography and Security
url https://arxiv.org/abs/2312.15285