Many-body Quantum Chaos and Entanglement in a Quantum Ratchet
  We uncover signatures of quantum chaos in the many-body dynamics of a Bose-Einstein condensate-based quantum ratchet in a toroidal trap. We propose measures including entanglement, condensate depletion, and spreading over a fixed basis in many-body Hilbert space which quantitatively identify the region in which quantum chaotic many-body dynamics occurs, where random matrix theory is limited or inaccessible. With these tools we show that many-body quantum chaos is neither highly entangled nor delocalized in the Hilbert space, contrary to conventionally expected signatures of quantum chaos. 
Marc Andrew Valdez, Gavriil Shchedrin, Martin Heimsoth, Charles E.   Creffield, Fernando Sols, Lincoln D. Carr
cond-mat.quant-gas