# Semi-device-independent certification of indefinite causal order

@article{Bavaresco2019SemideviceindependentCO, title={Semi-device-independent certification of indefinite causal order}, author={Jessica Bavaresco and Mateus Ara'ujo and {\vC}aslav Brukner and Marco T'ulio Quintino}, journal={Quantum}, year={2019} }

When transforming pairs of independent quantum operations according to the fundamental rules of quantum theory, an intriguing phenomenon emerges: some such higher-order operations may act on the input operations in an indefinite causal order. Recently, the formalism of process matrices has been developed to investigate these noncausal properties of higher-order operations. This formalism predicts, in principle, statistics that ensure indefinite causal order even in a device-independent scenario…

## 9 Citations

Device-independent certification of indefinite causal order in the quantum switch

- Philosophy
- 2022

Quantum theory is compatible with scenarios in which the order of operations is indeﬁnite. Experimental investigations of such scenarios, all of which have been based on a process known as the…

Quantum processes without a causal order

- PhysicsPhotonics for Quantum
- 2022

Less than ten years ago it was realized that quantum theory permits the existence of processes which do not have a defined causal order. To date, several experiments have confirmed the existence of…

Consequences of preserving reversibility in quantum superchannels

- PhysicsQuantum
- 2021

This paper provides a mathematical characterization for pure superchannels with two slots (also known as bipartite pure processes), which are superch channels preserving the reversibility of quantum operations, and shows that the reversible preserving condition restricts all pure super channels withTwo slots to be either a causally ordered quantum circuit only consisting of unitary operations or a coherent superposition of two pure causally order circuits.

Causal orders, quantum circuits and spacetime: distinguishing between definite and superposed causal orders

- Physics, PhilosophyQuantum
- 2020

It is shown that every circuit can be immersed into a classical spacetime, preserving the compatibility between the two causal structures, and a recently introduced operational notion of an event does allow for superpositions of respective causal orders in flat spacetime quantum switch implementations.

Practical computational advantage from the quantum switch on a generalized family of promise problems

- Computer Science
- 2022

The “query per gate” parameter is introduced and used to prove that the quantum switch provides computational advantage for both the continuous and discrete cases and leads to the conclusion that a continuous variable system is necessary to implement the most general promise problem.

“All-versus-nothing” proof of genuine tripartite steering and entanglement certification in the two-sided device-independent scenario

- PhysicsQuantum Studies: Mathematics and Foundations
- 2022

We consider the task of certification of genuine entanglement of tripartite states. For this purpose, we first present an “all-versus-nothing” proof of genuine tripartite Einstein-Podolsky-Rosen…

Reversible dynamics with closed time-like curves and freedom of choice

- PhysicsClassical and Quantum Gravity
- 2020

This work characterisation to an arbitrary number of regions of spacetime finds that there exist several inequivalent processes that can only arise due to non-trivial time travel, which supports the view that complex dynamics is possible in the presence of CTCs, compatible with free choice of local operations and free of inconsistencies.

Unitary channel discrimination beyond group structures: Advantages of sequential and indefinite-causal-order strategies

- Computer ScienceJournal of Mathematical Physics
- 2022

An absolute upper bound for the maximal probability of successfully discriminating any set of unitary channels with any number of copies for the most general strategies that are suitable for channel discrimination is derived.

Hidden nonmacrorealism: Reviving the Leggett-Garg inequality with stochastic operations

- PhysicsPhysical Review Research
- 2021

Huan-Yu Ku, 2, ∗ Hao-Cheng Weng, ∗ Yen-An Shih, Po-Chen Kuo, 2 Neill Lambert, Franco Nori, 4 Chih-Sung Chuu, † and Yueh-Nan Chen 2, ‡ Department of Physics and Center for Quantum Frontiers of…

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