The characterization and classification of multipartite entanglement is crucial for the investigation of many-body systems, foundational problems and quantum technologies. A central goal of the MENTA project is to discover robust, experimentally accessible criteria to witness and explore the many facets of quantum correlations. Multipartite entanglement provides formidable challenges arising from the exponential increase of the HIlbert space dimension with the number of the quantum system constituents. For instance, the full classification of multipartite entanglement is missing in the literature, and the possibility to witness the classes of entangled states allowing quantum advantages in different quantum information applications is still largely unexplored.
The experimental groups in this project have substantial infrastructure permitting the use of ultra-cold atoms and their detection. The techniques include: coherent spin manipulation, atom chips, Bose-Einstein condensates, atom interferometry and arrays of optical tweezers. They have already developed powerful atom detection techniques with: high quantum efficiency, a capacity for the detection of multiple atoms and their correlations as well as good spatial resolution, all of which will be used to develop experimental protocols for witnessing multipartite entanglement.
A crucial asset is the dedicated collaboration of two theoretical groups to guide the exploration of the many possible experimental strategies to make these characterizations. The high degree of experimental control and detection efficiencies will permit the evaluation of Fisher information the Dyson rank and other multipartite entanglement witnesses based on the measurement of collective variables. Significant efforts will be dedicated to investigate novel quantifiers specifically tailored to the experimental platforms created in this project. Successful completion of this project will provide to the community a deeper understanding of multipartite entanglement and its relation with fundamental and technological applications.
Coordinator: Christoph Westbrook (Laboratoire Charles Fabry de l’Institut d’Optique, FR)
Carsten Klempt (Leibniz University Hannover, DE)
Jörg Schmiedmayer (Technische Universität Wien, AT)
Géza Tóth (University of the Basque Country, ES)
Augusto Smerzi (Consiglio Nazioneale delle Ricerche, IT)
The characterization and classification of multipartite entanglement is crucial for the investigation of many-body systems, foundational problems and quantum technologies. A central goal is to discover robust, experimentally accessible criteria to witness and explore the many facets of quantum correlations. Multipartite entanglement provides formidable challenges arising from the exponential increase of the Hilbert space dimension with the number of the quantum system constituents. For instance, the full classification of multipartite entanglement is missing in the literature, and the possibility to witness the classes of entangled states allowing quantum advantages in different quantum information applications is still largely unexplored.
- Entanglement depths and related concepts, and their detection (Florence)
The entanglement depth is not the only quantitier of multipartite entanglement and that further parameters are needed. Very recenily, the so-called Dyson rank has been suggested, which is defined as r= w - h, where w is the quantum information processing and h is the number of separable partitions.
Metrological detection of multipartite entanglement from young diagrams
Z. Ren, W. Li, A. Smerzi, M. Gessner
Phys. Rev. Lett. 126 (8), 080502 (2021)
Background: Sz. Szalay,
k-stretchability of entanglement, and the duality of k-separability and k-producibility,
Quantum 3, 204 (2019)
- Detection of bipartite entanglement in large particle ensembles (Bilbao)
We can divide the collection of atoms into spatially separated entangled sub-ensembles. This step is important for the unltracold gas community, since quantum information processing and even Bell inequality tests need spatially separated qudits.
G. Vitagliano, M. Fadel, I. Apellaniz, M. Kleinmann, B. Lücke, C. Klempt, G. Tóth,
Number-phase uncertainty relations and bipartite entanglement detection in spin ensembles,
Quantum 7, 914 (2023).
- Dynamical optical potentials for Rb atoms at demonstrated LUH
Atoms are prepared in entangled spin states and are then separated in multiple wells in a spin-independent way.
- Multiparticle interferometry experiment at LCF
Correlated atom pairs are generated in the source at time t = 0. Standing wave lasers recombine paths. Multiple atoms and their correlations are recorded.
- Correlation pair production at TUW
Afoms are trapped on an atom chip in a one-dimensional geometry. They are then excited transversely and decay as correlated pairs. Correlations, and entanglement are probed by manipulation of the trapping potential.
- Optical tweezer arrays for Sr Rydberg atoms at CNR-INO
Rydberg-based entanglement is created between Sr atoms trapped in optical tweezers within the Rydberg blockade radius. Separated ensembles with variable number of parties are realized.
