Interacting Atoms in Optical Lattices

The PI and his group will perform a series of experiments with gases of atoms confined in one dimension (1D). 1D gases are the rare many-body quantum system that can be accurately modeled theoretically, even when they are taken out of equilibrium. Their out-of-equilibrium behavior can also be precisely measured experimentally. For two decades, parallel progress in 1D gas experiments and theory have increased our understanding of many-body quantum systems, especially out of equilibrium. Such understanding is increasingly important for quantum computing, quantum simulation and quantum sensing. These new experiments will expand the reach of 1D gas models by controllably relaxing the aspect of 1D gases that has made them so amenable to theoretical study, a feature called “integrability”. The 1D gases will be taken from nearly integrable to non-integrable, along a path that retains the experimental precision and explanatory clarity that has characterized previous 1D gas studies. Success will bring us closer to a universal understanding of many-body quantum dynamics, deepening our understanding of nature and likely impacting emerging quantum technologies. Work on these experiments will teach graduate students cutting edge technologies and physical theories and prepare them for future work across the gamut of quantum science and technologies.The PI and his group will make a series of measurements of 1D Bose gases, which consist of ultra-cold 87Rb atoms trapped in a 2D optical lattice, which forms a 2D array of tubes for the atoms. Specifically, they will superimpose an additional 1D lattice onto the 1D gases, creating a 1D lattice-gas. The additional 1D lattice turns the system from nearly integrable to non-integrable. The group will measure the 1D lattice-gas analog of well-studied quantities of the 1D gas, both in an out of equilibrium. These quantities include momentum distributions and distributions of rapidities, which are the momenta of the quasiparticles that account for interparticle interactions. The lattice-gas versions of these quantities are well-defined operationally in much of the non-integrable regime. The goal is to use them as the basis for modeling dynamics. The overarching goal is to create as universal a framework as possible for the study of out-of-equilibrium many-body quantum systems. Understanding the dynamics of closed quantum many-body systems is important for validating quantum simulations, especially with atoms in optical lattices. The understanding gleaned could also be relevant to other closed or nearly closed interacting quantum systems, including quantum computers and quantum sensors, especially those that involve squeezing or other particle-particle interactions. The training in experimental physics obtained by undergraduates and graduate students working on this experiment is comprehensive; it is good preparation for many different types of experimental work.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.