Experiments on quantum causality

Abstract

Quantum causality extends the conventional notion of fixed causal structure by allowing channels and operations to act in an indefinite causal order. The importance of such an indefinite causal order ranges from the foundational---e.g. towards a theory of quantum gravity---to the applied---e.g. for advantages in communication and computation. In this review, we will walk through the basic theory of indefinite causal order and focus on experiments that rely on a physically realisable indefinite causal ordered process---the quantum switch.

References in corpus (26)

• Entanglement detection
• Quantum correlations with no causal order
• Quantum computations without definite causal structure
• Theoretical framework for quantum networks
• Experimental Superposition of Orders of Quantum Gates
• Computational advantage from quantum-controlled ordering of gates
• Experimental Verification of an Indefinite Causal Order
• Enhanced communication with the assistance of indefinite causal order
• Perfect discrimination of no-signalling channels via quantum superposition of causal structures
• Indefinite Causal Order in a Quantum Switch
• Towards Quantum Gravity: A Framework for Probabilistic Theories with Non-Fixed Causal Structure
• Exponential Communication Complexity Advantage from Quantum Superposition of the Direction of Communication
• Witnessing causal nonseparability
• Experimental transmission of quantum information using a superposition of causal orders
• Experimental Quantum Switching for Exponentially Superior Quantum Communication Complexity
• Bell's Theorem for Temporal Order
• Quantum computation with programmable connections between gates
• Quantum Switch for the Quantum Internet: Noiseless Communications through Noisy Channels
• Communicating via ignorance: Increasing communication capacity via superposition of order
• Communication through quantum-controlled noise
• Time-delocalized quantum subsystems and operations: on the existence of processes with indefinite causal structure in quantum mechanics
• Resource theories of communication
• Updating the Born rule
• Quantum computation with indefinite causal structures
• On the definition and characterisation of multipartite causal (non)separability
• Classical and Quantum Causal Interventions

Cited by in corpus (34)

• Indefinite causal order enables perfect quantum communication with zero capacity channels
• Work extraction from coherently activated maps via quantum switch
• Quantum and Classical Data Transmission through Completely Depolarising Channels in a Superposition of Cyclic Orders
• Experimental Aspects of Indefinite Causal Order in Quantum Mechanics
• Thermal devices powered by generalized measurements with indefinite causal order
• Beyond Shannon Limits: Quantum Communications through Quantum Paths
• Deterministic transformations between unitary operations: Exponential advantage with adaptive quantum circuits and the power of indefinite causality
• Random-Receiver Quantum Communication
• Causal structure in the presence of sectorial constraints, with application to the quantum switch
• Measuring incompatibility and clustering quantum observables with a quantum switch
• Exploring quantum thermodynamics with NMR
• Identification is Pointless: Quantum Coordinates, Localisation of Events, and the Quantum Hole Argument
• On single-photon and classical interference
• Reassessing thermodynamic advantage from indefinite causal order
• Quantum communication through devices with indefinite input-output direction
• Embedding cyclic information-theoretic structures in acyclic spacetimes: no-go results for indefinite causality
• Experimentally demonstrating indefinite causal order algorithms to solve the generalized Deutsch's problem
• Fundamental limits for realising quantum processes in spacetime
• Quantum communication using a quantum switch of quantum switches
• Breaking the limits of purification: Postselection enhances heat-bath algorithmic cooling
• Quantum switch in the gravity of Earth
• Gravitational quantum switch on a superposition of spherical shells
• Memory in quantum processes with indefinite time direction and causal order
• Quantum networks boosted by entanglement with a control system
• Lightcone Bounds for Quantum Circuit Mapping via Uncomplexity
• Interplay between the Hilbert-space dimension of a control system and the memory induced by a quantum SWITCH
• The Möbius game and other Bell tests for relativity
• Quantum theory cannot violate a causal inequality
• Quantum switch as a thermodynamic resource in the context of passive states
• Entropic uncertainty under indefinite causal order and input-output direction
• Correlations in a quantum switch-based heat engine with measurements: A proof-of-principle demonstration
• Witnessing latent time correlations with a single quantum particle
• Causality in a qubit-based quantum switch
• Quantum probabilities for the causal ordering of events