Physics Colloquium

Synthetic quantum matter, atom by atom: digitally enhanced analog quantum simulation

Understanding strongly interacting quantum matter is one of the central challenges of modern physics, from the phases of correlated electrons to the real-time dynamics of gauge theories. For many of these problems the cost of classical computation grows exponentially with system size. Analog quantum simulators built from ultracold atoms in optical lattices take a different route. They realize a synthetic quantum material of several thousand atoms, in which every atom can be imaged and controlled individually. Their power has so far been limited by what an analog machine can natively prepare and measure. In this talk I will show how adding digital control elements lifts this limitation. Local operations between neighboring sites give access to observables that are invisible to density measurements. We have used them to realize strongly interacting Meissner phases in bosonic flux ladders and to characterize them through the chiral currents that screen an applied magnetic flux, much as a superconductor expels a magnetic field. Non-equilibrium protocols are a distinctive feature of programmable simulators: they open new ways of preparing complex many-body states even when the Hamiltonian at hand does not support them as a ground-state phase. We use this to realize a two-dimensional U(1) lattice gauge theory on more than 3,000 sites and to prepare a quantum spin liquid, a highly entangled state without conventional order. Using round-trip interferometric protocols, we extract a characteristic size of the spin-liquid regions of about 100 lattice sites. I will close with an outlook on a fermionic ytterbium platform that extends these ideas toward unifying quantum simulation, computation, and precision metrology.

Join via Zoom: https://caltech.zoom.us/j/84497014003

Meeting ID: 844 9701 4003