  Population annealing is a sequential Monte Carlo scheme well-suited to
simulating equilibrium states of systems with rough free energy landscapes.
Here we use population annealing to study a binary mixture of hard spheres.
Population annealing is a parallel version of simulated annealing with an extra
resampling step that ensures that a population of replicas of the system
represents the equilibrium ensemble at every packing fraction in an annealing
schedule. The algorithm and its equilibration properties are described and
results are presented for a glass-forming fluid composed of a 50/50 mixture of
hard spheres with diameter ratio of 1.4:1. For this system, we obtain precise
results for the equation of state in the glassy regime up to packing fractions
$\varphi \approx 0.60$ and study deviations from the BMCSL equation of state.
For higher packing fractions, the algorithm falls out of equilibrium and a free
volume fit predicts jamming at packing fraction $\varphi \approx 0.667$. We
conclude that population annealing is an effective tool for studying
equilibrium glassy fluids and the jamming transition.
