Experimental aspects of indefinite causal order in quantum mechanics

LA Rozema, T Strömberg, H Cao, Y Guo, BH Liu… - Nature Reviews …, 2024 - nature.com
In the past decade, the toolkit of quantum information has been expanded to include
processes in which the basic operations do not have definite causal relations. Originally …

Experiments on quantum causality

K Goswami, J Romero - AVS Quantum Science, 2020 - pubs.aip.org
Quantum causality extends the conventional notion of the fixed causal structure by allowing
channels and operations to act in an indefinite causal order. The importance of such an …

Strict hierarchy between parallel, sequential, and indefinite-causal-order strategies for channel discrimination

J Bavaresco, M Murao, MT Quintino - Physical review letters, 2021 - APS
We present an instance of a task of minimum-error discrimination of two qubit-qubit quantum
channels for which a sequential strategy outperforms any parallel strategy. We then …

Cyclic quantum causal models

J Barrett, R Lorenz, O Oreshkov - Nature communications, 2021 - nature.com
Causal reasoning is essential to science, yet quantum theory challenges it. Quantum
correlations violating Bell inequalities defy satisfactory causal explanations within the …

Quantum circuits with classical versus quantum control of causal order

J Wechs, H Dourdent, AA Abbott, C Branciard - PRX Quantum, 2021 - APS
Quantum supermaps are transformations that map quantum operations to quantum
operations. It is known that quantum supermaps which respect a definite, predefined causal …

[HTML][HTML] Communication through coherent control of quantum channels

AA Abbott, J Wechs, D Horsman, M Mhalla… - Quantum, 2020 - quantum-journal.org
A completely depolarising quantum channel always outputs a fully mixed state and thus
cannot transmit any information. In a recent Letter [3], it was however shown that if a …

Communication through quantum-controlled noise

PA Guérin, G Rubino, Č Brukner - Physical Review A, 2019 - APS
In a recent series of works [Ebler, Phys. Rev. Lett. 120, 120502 (2018) PRLTAO 0031-9007
10.1103/PhysRevLett. 120.120502; arxiv: 1809.06655 v2; arxiv: 1810.10457 v2], it has …

Computational advantage from the quantum superposition of multiple temporal orders of photonic gates

MM Taddei, J Cariñe, D Martínez, T García, N Guerrero… - PRX Quantum, 2021 - APS
Models for quantum computation with circuit connections subject to the quantum
superposition principle have recently been proposed. In them, a control quantum system can …

Time-delocalized quantum subsystems and operations: on the existence of processes with indefinite causal structure in quantum mechanics

O Oreshkov - Quantum, 2019 - quantum-journal.org
It has been shown that it is theoretically possible for there to exist higher-order quantum
processes in which the operations performed by separate parties cannot be ascribed a …

Communication Enhancement through Quantum Coherent Control of N Channels in an Indefinite Causal-Order Scenario

LM Procopio, F Delgado, M Enríquez, N Belabas… - Entropy, 2019 - mdpi.com
In quantum Shannon theory, transmission of information is enhanced by quantum features.
Up to very recently, the trajectories of transmission remained fully classical. Recently, a new …