Significant progress has been made with multipartite entanglement of discrete qubits, but continuous variable systems may provide a more scalable path toward entanglement of large ensembles. We demonstrate multipartite entanglement in a microwave frequency comb generated by a Josephson parametric amplifier subject to a bichromatic pump. We find 64 correlated modes in the transmission line using a multifrequency digital signal processing platform. Full inseparability is verified in a subset of seven modes. Our method can be expanded to generate even more entangled modes in the near future.
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http://dx.doi.org/10.1103/PhysRevLett.130.120601 | DOI Listing |
Phys 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.
View Article and Find Full Text PDFNat Commun
November 2024
Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, China.
Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been restricted to second-order EPs (EP2s) in classical or semiclassical systems. We here propose an NH multi-mode system with higher-order EPs, each of which is underlain by a multifold-degenerate multipartite entangled eigenstate.
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