Scalable spin squeezing from spontaneous breaking of a continuous symmetry

Spontaneous symmetry breaking is a property of Hamiltonian equilibrium states which, in the thermodynamic limit, retain a finite average value of an order parameter even after a field coupled to it is adiabatically turned off. In the case of quantum spin models with continuous symmetry, we show that this adiabatic process is also accompanied by the suppression of the fluctuations of the symmetry generator—namely, the collective spin component along an axis of symmetry.
arXiv:2202.08607 (2022) / Phys. Rev. Lett. 129, 113201 (2022)

Measuring densities of cold atomic clouds smaller than the resolution limit

We propose and demonstrate an experimental method to measure by absorption imaging the size and local column density of a cloud of atoms, even when its smallest dimension is smaller than the resolution of the imaging system.
arXiv:2105.10296 (2021) / Physical Review A 104, 033309 (2021)