Channel capacity enhancement with indefinite causal order

Abstract

Classical communication capacity of a channel can be enhanced either through a device called a 'quantum switch' or by putting the channel in a quantum superposition. The gains in the two cases, although different, have their origin in the use of a quantum resource, but is it the same resource? Here this question is explored through simulating large sets of random channels. We find that quantum superposition always provides an advantage, while the quantum switch does not: it can either increase or decrease communication capacity. The origin of this discrepancy can be attributed to a subtle combination of superposition and non-commutativity.

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Cited by in corpus (24)

• Experimental Quantum Communication Enhancement by Superposing Trajectories
• Communication through coherent control of quantum channels
• Resource theories of communication
• Quantum circuits with classical versus quantum control of causal order
• Noisy quantum metrology with the assistance of indefinite causal order
• Quantum and Classical Data Transmission through Completely Depolarising Channels in a Superposition of Cyclic Orders
• Classical Communications with Indefinite Causal Order for $N$ completely depolarizing channels
• Quantum parameter estimation on coherently superposed noisy channels
• Indefinite causal order for quantum metrology with quantum thermal noise
• Quick charging of a quantum battery with superposed trajecotries
• Measuring incompatibility and clustering quantum observables with a quantum switch
• Reassessing thermodynamic advantage from indefinite causal order
• Space-time dual quantum Zeno effect: Interferometric engineering of open quantum system dynamics
• Quantum communication through devices with indefinite input-output direction
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• Maxwell's two-demon engine under pure dephasing noise
• Quantum networks boosted by entanglement with a control system
• Indefinite causal key distribution
• Indefinite Time Directed Quantum Metrology
• Boosting entanglement growth of many-body localization by superpositions of disorder
• Emergent non-Markovianity and dynamical quantification of the quantum switch
• Expressibility, entangling power and quantum average causal effect for causally indefinite circuits
• Multifold behavior of the information transmission by the quantum 3-switch
• Thermodynamic criteria for signaling in quantum channels