Experimental Quantum Switching for Exponentially Superior Quantum Communication Complexity

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Author(s)
Wei, Kejin
Tischler, Nora
Zhao, Si-Ran
Li, Yu-Huai
Arrazola, Juan Miguel
Liu, Yang
Zhang, Weijun
Li, Hao
You, Lixing
Wang, Zhen
Chen, Yu-Ao
Sanders, Barry C
Zhang, Qiang
Pryde, Geoff J
Xu, Feihu
Pan, Jian-Wei
Year published
2019
Metadata
Show full item recordAbstract
Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication complexity. Recently, a novel quantum resource called the quantum switch—which creates a coherent superposition of the causal order of events, known as quantum causality—has been harnessed theoretically in a new protocol providing provable exponential separation. We experimentally demonstrate such an advantage by realizing a superposition of communication directions for a two-party distributed ...
View more >Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication complexity. Recently, a novel quantum resource called the quantum switch—which creates a coherent superposition of the causal order of events, known as quantum causality—has been harnessed theoretically in a new protocol providing provable exponential separation. We experimentally demonstrate such an advantage by realizing a superposition of communication directions for a two-party distributed computation. Our photonic demonstration employs d-dimensional quantum systems, qudits, up to d=2 13 dimensions and demonstrates a communication complexity advantage, requiring less than (0.696±0.006) times the communication of any causally ordered protocol. These results elucidate the crucial role of the coherence of communication direction in achieving the exponential separation for the one-way processing task, and open a new path for experimentally exploring the fundamentals and applications of advanced features of indefinite causal structures.
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View more >Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication complexity. Recently, a novel quantum resource called the quantum switch—which creates a coherent superposition of the causal order of events, known as quantum causality—has been harnessed theoretically in a new protocol providing provable exponential separation. We experimentally demonstrate such an advantage by realizing a superposition of communication directions for a two-party distributed computation. Our photonic demonstration employs d-dimensional quantum systems, qudits, up to d=2 13 dimensions and demonstrates a communication complexity advantage, requiring less than (0.696±0.006) times the communication of any causally ordered protocol. These results elucidate the crucial role of the coherence of communication direction in achieving the exponential separation for the one-way processing task, and open a new path for experimentally exploring the fundamentals and applications of advanced features of indefinite causal structures.
View less >
Journal Title
PHYSICAL REVIEW LETTERS
Volume
122
Issue
12
Copyright Statement
© 2019 American Physical Society. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Subject
Mathematical sciences
Physical sciences
Engineering