An analysis is conducted of the multipartite entanglement for Gaussian states generated by the parametric down-conversion of a femtosecond frequency comb. Using a recently introduced method for constructing optimal entanglement criteria, a family of tests is formulated for mode decompositions that extends beyond the traditional bipartition analyses. A numerical optimization over this family is performed to achieve maximal significance of entanglement verification. For experimentally prepared 4-, 6-, and 10-mode states, full entanglement is certified for all of the 14, 202, and 115 974 possible nontrivial partitions, respectively.
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http://dx.doi.org/10.1103/PhysRevLett.114.050501 | DOI Listing |
Entropy (Basel)
November 2024
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China.
Controlled quantum teleportation is an important extension of multipartite quantum teleportation, which plays an indispensable role in building quantum networks. Compared with discrete variable counterparts, continuous variable controlled quantum teleportation can generate entanglement deterministically and exhibit higher superiority of the supervisor's authority. Here, we define a measure to quantify the control power in continuous variable controlled quantum teleportation via Greenberger-Horne-Zeilinger-type entangled coherent state channels.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea and Division of Quantum Information Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea.
High-dimensional multipartite entanglement plays a crucial role in quantum information science. However, existing schemes for generating such entanglement become complex and costly as the dimension of quantum units increases. In this Letter, we overcome the limitation by proposing a significantly enhanced linear optical heralded scheme that generates the d-level N-partite Greenberger-Horne-Zeilinger (GHZ) state with single-photon sources and linear operations.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Physics and HK Institute of Quantum Science & Technology, The University of Hong Kong, Hong Kong, Hong Kong.
Quantum entanglement uncovers the essential principles of quantum matter, yet determining its structure in realistic many-body systems poses significant challenges. Here, we employ a protocol, dubbed entanglement microscopy, to reveal the multipartite entanglement encoded in the full reduced density matrix of the microscopic subregion in spin and fermionic many-body systems. We exemplify our method by studying the phase diagram near quantum critical points (QCP) in 2 spatial dimensions: the transverse field Ising model and a Gross-Neveu-Yukawa transition of Dirac fermions.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
December 2024
Physics Department, University of Strathclyde, Glasgow G4 0NG, UK.
The controlled SWAP test for detecting and quantifying entanglement applied to pure qubit states is robust to small errors in the states and efficient for large multi-qubit states (Foulds . 2021 . , 035002 (doi:10.
View Article and Find Full Text PDFScience
December 2024
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
Collective phenomena arise from interactions within complex systems, leading to behaviors absent in individual components. Observing quantum collective phenomena with macroscopic mechanical oscillators has been impeded by the stringent requirement that oscillators be identical. We demonstrate the quantum regime for collective motion of = 6 mechanical oscillators, a hexamer, in a superconducting circuit optomechanical platform.
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