Accessible Quantifiers of Multipartite Entanglement in Atomic Systems

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.


Call topic

Quantum Phenomena and Resources

Start date

April 2022


36 months

Funding support

€ 1 373 600

Dynamical optical potential for Rb atoms, demonstrated at LUH. Atoms are prepared in entangled spin states and are then separated in multiple wells in a spin-independent way, creating a rich variety of multipartite entanglement possibilities.

Correlated pair production scheme at TUW. Atoms are trapped on an atom chip in a one dimensional geometry. They are then excited transversely and decay as correlated pairs into a double well.  The correlations, interference and entanglement can then be probed by manipulation of the trapping potential.

Schematic diagram of a typical multiparticle interferometry experiment at the LCF. Correlated atom pairs are generated in source at time t = 0 having different momenta. The atom with momentum p is always accompanied by one with momentum -p. At later time, standing wave lasers form deflectors and beam splitters through Bragg diffraction. Multiple atoms are detected in the various momentum modes, and their correlations are recorded.

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. Different approaches for the creation of entanglement will be explored, including GHZ-like entanglement obtained by combining Rydberg excitation with local manipulation beams [Omran 2019] and Loschmidt echo [Macri 2016] based  on excitations to other internal degrees of freedom (e.g. metastable clock state). The configurable geometry of the array will allow the realization of separated ensembles with variable number of parties.


  • 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)