All Publications

  • Programmable interactions and emergent geometry in an arrayof atom clouds. Nature Periwal, A., Cooper, E. S., Kunkel, P., Wienand, J. F., Davis, E. J., Schleier-Smith, M. 1800; 600 (7890): 630-635


    Interactions govern the flow of information and the formation of correlations between constituents of many-body quantum systems, dictating phases of matter found in nature and forms of entanglement generated in the laboratory. Typical interactions decay with distance and thus produce a network of connectivity governed by geometry-such as the crystalline structure of a material or the trapping sites of atoms in a quantum simulator1,2. However, many envisioned applications in quantum simulation and computation require more complex coupling graphs including non-local interactions, which feature in models of information scrambling in black holes3-6 and mappings of hard optimization problems onto frustrated classical magnets7-11. Here we describe the realization of programmable non-local interactions in an array of atomic ensembles within an optical cavity, in which photons carry information between atomic spins12-19. By programming the distance dependence of the interactions, we access effective geometries for which the dimensionality, topology and metric are entirely distinct from the physical geometry of the array. As examples, we engineer an antiferromagnetic triangular ladder, a Mobius strip with sign-changing interactions and a treelike geometry inspired by concepts of quantum gravity5,20-22. The tree graph constitutes a toy model of holographic duality21,22, in which the quantum system lies on the boundary of a higher-dimensional geometry that emerges from measured correlations23. Our work provides broader prospects for simulating frustrated magnets and topological phases24, investigating quantum optimization paradigms10,11,25,26 and engineering entangled resource states for sensing and computation27,28.

    View details for DOI 10.1038/s41586-021-04156-0

    View details for PubMedID 34937894

  • Number Partitioning With Grover's Algorithm in Central Spin Systems PRX QUANTUM Anikeeva, G., Markovic, O., Borish, V., Hines, J. A., Rajagopal, S., Cooper, E. S., Periwal, A., Safavi-Naeini, A., Davis, E. J., Schleier-Smith, M. 2021; 2 (2)
  • Protecting Spin Coherence in a Tunable Heisenberg Model. Physical review letters Davis, E. J., Periwal, A., Cooper, E. S., Bentsen, G., Evered, S. J., Van Kirk, K., Schleier-Smith, M. H. 2020; 125 (6): 060402


    Using an ensemble of atoms in an optical cavity, we engineer a family of nonlocal Heisenberg Hamiltonians with continuously tunable anisotropy of the spin-spin couplings. We thus gain access to a rich phase diagram, including a paramagnetic-to-ferromagnetic Ising phase transition that manifests as a diverging magnetic susceptibility at the critical point. The susceptibility displays a symmetry between Ising interactions and XY (spin-exchange) interactions of the opposite sign, which is indicative of the spatially extended atomic system behaving as a single collective spin. Images of the magnetization dynamics show that spin-exchange interactions protect the coherence of the collective spin, even against inhomogeneous fields that completely dephase the noninteracting and Ising systems. Our results underscore prospects for harnessing spin-exchange interactions to enhance the robustness of spin squeezing protocols.

    View details for DOI 10.1103/PhysRevLett.125.060402

    View details for PubMedID 32845652

  • Photon-mediated spin-mixing dynamics Bentsen, G. S., Davis, E. J., Homeier, L., Periwal, A., Cooper, E., Van Kirk, K., Schleier-Smith, M. H., Shahriar, S. M., Scheuer, J. SPIE-INT SOC OPTICAL ENGINEERING. 2019

    View details for DOI 10.1117/12.2515795

    View details for Web of Science ID 000466478500031

  • Three-Path Atom Interferometry with Large Momentum Separation PHYSICAL REVIEW LETTERS Plotkin-Swing, B., Gochnauer, D., McAlpine, K. E., Cooper, E. S., Jamison, A. O., Gupta, S. 2018; 121 (13): 133201


    We demonstrate the scale up of a symmetric three-path contrast interferometer to large momentum separation. The observed phase stability at separation of 112 photon recoil momenta exceeds the performance of earlier free-space interferometers. In addition to the symmetric interferometer geometry and Bose-Einstein condensate source, the robust scalability of our approach relies on the suppression of undesired diffraction phases through a careful choice of atom optics parameters. The interferometer phase evolution is quadratic with number of recoils, reaching a rate as high as 7×10^{7}  rad/s. We discuss the applicability of our method towards a new measurement of the fine-structure constant and a test of QED.

    View details for DOI 10.1103/PhysRevLett.121.133201

    View details for Web of Science ID 000445733100007

    View details for PubMedID 30312085

  • Gyroscopic stabilization minimizes drag on Ruellia ciliatiflora seeds JOURNAL OF THE ROYAL SOCIETY INTERFACE Cooper, E. S., Mosher, M. A., Cross, C. M., Whitaker, D. L. 2018; 15 (140)


    Fruits of Ruellia ciliatiflora (Acanthaceae) explosively launch small (2.5 mm diameter × 0.46 mm thick), disc-shaped seeds at velocities over 15 m s-1, reaching distances of up to 7 m. Through high-speed video analysis, we observe that seeds fly with extraordinary backspin of up to 1660 Hz. By modelling the seeds as spinning discs, we show that flying with backspin is stable against gyroscopic precession. This stable backspin orientation minimizes the frontal area during flight, decreasing drag force on the seeds and thus increasing dispersal distance. From high-speed video of the seeds' flight, we experimentally determine drag forces that are 40% less than those calculated for a sphere of the same volume and density. This reduces the energy costs for seed dispersal by up to a factor of five.

    View details for DOI 10.1098/rsif.2017.0901

    View details for Web of Science ID 000428576200012

    View details for PubMedID 29514987

    View details for PubMedCentralID PMC5908531