Entanglement-assisted classical communication can simulate classical communication without causal order

Abstract

Phenomena induced by the existence of entanglement, such as nonlocal correlations, exhibit characteristic properties of quantum mechanics distinguishing from classical theories. When entanglement is accompanied by classical communication, it enhances the power of quantum operations jointly performed by two spatially separated parties. Such a power has been analyzed by the gap between the performances of joint quantum operations implementable by local operations at each party connected by classical communication with and without the assistance of entanglement. In this work, we present a new formulation for joint quantum operations connected by classical communication beyond special relativistic causal order but without entanglement and still within quantum mechanics. Using the formulation, we show that entanglement assisting classical communication necessary for implementing a class of joint quantum operations called separable maps can be interpreted to simulate "classical communication" not respecting causal order. Our results reveal a new counter-intuitive aspect of entanglement related to spacetime.

References in corpus (6)

• Experimental Superposition of Orders of Quantum Gates
• Multipartite Nonlocality without Entanglement in Many Dimensions
• Towards Quantum Gravity: A Framework for Probabilistic Theories with Non-Fixed Causal Structure
• Closed timelike curves via post-selection: theory and experimental demonstration
• The quantum mechanics of time travel through post-selected teleportation
• Nonlocal Entanglement Transformations Achievable by Separable Operations

Cited by in corpus (6)

• A resource theory of quantum memories and their faithful verification with minimal assumptions
• Optimal quantum networks and one-shot entropies
• Quantum superposition of causal structures as a universal resource for local implementation of nonlocal quantum operations
• Interplay between the Hilbert-space dimension of a control system and the memory induced by a quantum SWITCH
• Trading causal order for locality
• Multi-system measurements in generalized probabilistic theories and their role in information processing