Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states

Fuente: arXiv
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Main Authors: Liu, Xiangjing, Jia, Zhian, Qiu, Yixian, Li, Fei, Dahlsten, Oscar
Format: Preprint
Published: 2023
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author Liu, Xiangjing
Jia, Zhian
Qiu, Yixian
Li, Fei
Dahlsten, Oscar
author_facet Liu, Xiangjing
Jia, Zhian
Qiu, Yixian
Li, Fei
Dahlsten, Oscar
contents We consider the relation between three different approaches to defining quantum states across several times and locations: the pseudo-density matrix (PDM), the process matrix, and the multiple-time state approaches. Previous studies have shown that bipartite two-time states can reproduce the statistics of bipartite process matrices. Here, we show that the operational scenarios underlying two-time states can be represented as PDMs, and thereby construct a mapping from process matrices with measurements to PDMs. The existence of this mapping implies that PDMs can, like the process matrix, model processes with indefinite causal orders. The results contribute to the unification of quantum models of spatiotemporal states.
format Preprint
id arxiv_https___arxiv_org_abs_2306_05958
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states
Liu, Xiangjing
Jia, Zhian
Qiu, Yixian
Li, Fei
Dahlsten, Oscar
Quantum Physics
We consider the relation between three different approaches to defining quantum states across several times and locations: the pseudo-density matrix (PDM), the process matrix, and the multiple-time state approaches. Previous studies have shown that bipartite two-time states can reproduce the statistics of bipartite process matrices. Here, we show that the operational scenarios underlying two-time states can be represented as PDMs, and thereby construct a mapping from process matrices with measurements to PDMs. The existence of this mapping implies that PDMs can, like the process matrix, model processes with indefinite causal orders. The results contribute to the unification of quantum models of spatiotemporal states.
title Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states
topic Quantum Physics
url https://arxiv.org/abs/2306.05958