Experimental test of entangled histories

Cotler, Jordan; Duan, Luming; Hou, Panyu; Wilczek, Frank; Xu, Da; Yin, Zhang-qi; Zu, Chong

doi:10.1016/j.aop.2017.09.004

Cited by 18 publications

(26 citation statements)

References 40 publications

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“…Similar as Ref. [20], we find that there are boundaries between entangled histories and the classical histories.…”

Section: Temporal Ghz Tests With Arbitrary Time Nodes and Dimen-ssupporting

confidence: 85%

“…Hence, a gap is observed between the quantum prediction and classical prediction. For n = 4, d = 2, the GHZ-type test for entangled histories was performed with single photon experiment [20]. The quantum and classical predictions gap we proved here makes the GHZ-type entangled histories tests for arbitrary time nodes possible in experiment.…”

Section: A Temporal Ghz Test For Qubitsmentioning

confidence: 71%

“…In Ref. [20], the minimum of E t (4, 2) was calculated and proved. This corresponded to a qubit system with 3 time nodes.…”

Section: A Temporal Ghz Test For Qubitsmentioning

confidence: 99%

“…In 2016, the quantum entangled history was experimentally verified through a temporal Greenberger-Horne-Zeilinger (GHZ) test [18,19] for quantum entangled history state with 3 time nodes [20]. The classical stochastic processes were introduced as the representative of classical theories.…”

Section: Introductionmentioning

confidence: 99%

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Greenberger-Horne-Zeilinger test for multi-dimension and arbitrary time nodes entangled histories

Dong¹,

Chen²,

Xu³

et al. 2017

Science Bulletin

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Based on the framework of consistent history theory, the quantum entangled history was proposed in 2015 and experimentally verified through temporal Greenberger-Horne-Zeilinger (GHZ) test with 3 time nodes in 2016. In this paper, we extend the temporal GHZ test to arbitrary time nodes and even system dimensions. Then, we define a witness to distinguish between the quantum entangled histories and the classical histories. The minimums of the witness for the classical histories are calculated for arbitrary number of time nodes and the system dimensions 2 and ∞. It is found that the minimums of the witness for the classical histories is always larger than the quantum entangled histories minimum −1. Only when both the number of time nodes and system dimensions approach to infinity, the minimum of the witness for classical and quantum entangled histories are identical.

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“…Similar as Ref. [20], we find that there are boundaries between entangled histories and the classical histories.…”

Section: Temporal Ghz Tests With Arbitrary Time Nodes and Dimen-ssupporting

confidence: 85%

Section: A Temporal Ghz Test For Qubitsmentioning

confidence: 71%

“…In Ref. [20], the minimum of E t (4, 2) was calculated and proved. This corresponded to a qubit system with 3 time nodes.…”

Section: A Temporal Ghz Test For Qubitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Greenberger-Horne-Zeilinger test for multi-dimension and arbitrary time nodes entangled histories

Dong¹,

Chen²,

Xu³

et al. 2017

Science Bulletin

Self Cite

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show abstract

“…We can write any operator in B(H hist. ) as i1,i2,...,in c i1,i2,...,in X in ⊗ · · · ⊗ X i2 ⊗ X i1 (18) for some coefficients c i1,i2,...,in . Then Eqn.…”

Section: Spacetime Statesmentioning

confidence: 99%

Superdensity operators for spacetime quantum mechanics

Cotler

Jian

et al. 2018

J. High Energ. Phys.

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We introduce superdensity operators as a tool for analyzing quantum information in spacetime. Superdensity operators encode spacetime correlation functions in an operator framework, and support a natural generalization of Hilbert space techniques and Dirac's transformation theory as traditionally applied to standard density operators. Superdensity operators can be measured experimentally, but accessing their full content requires novel procedures. We demonstrate these statements on several examples. The superdensity formalism suggests useful definitions of spacetime entropies and spacetime quantum channels. For example, we show that the von Neumann entropy of a superdensity operator is related to a quantum generalization of the Kolmogorov-Sinai entropy, and compute this for a many-body system. We also suggest experimental protocols for measuring spacetime entropies.

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Experimentally Demonstrating Indefinite Causal Order Algorithms to Solve the Generalized Deutsch's Problem

Liu,

Meng,

Song

et al. 2024

Adv Quantum Tech

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Deutsch's algorithm is the first quantum algorithm to demonstrate an advantage over classical algorithms. Here, Deutsch's problem is generalized to functions and a quantum algorithm with an indefinite causal order is proposed to solve this problem. The algorithm not only reduces the number of queries to the black box by half compared to the classical algorithm, but also significantly decreases the complexity of the quantum circuit and the number of required quantum gates compared to the generalized Deutsch's algorithm. The algorithm is experimentally demonstrated in a stable Sagnac loop interferometer with a common path, which overcomes the obstacles of both phase instability and low fidelity of the Mach–Zehnder interferometer. The experimental results show both ultrahigh and robust success probabilities . This study opens a path toward solving practical problems with indefinite cause‐order quantum circuits.

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Experimental test of entangled histories

Cited by 18 publications

References 40 publications

Greenberger-Horne-Zeilinger test for multi-dimension and arbitrary time nodes entangled histories

Greenberger-Horne-Zeilinger test for multi-dimension and arbitrary time nodes entangled histories

Superdensity operators for spacetime quantum mechanics

Experimentally Demonstrating Indefinite Causal Order Algorithms to Solve the Generalized Deutsch's Problem

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