  Quantum Field Theories (QFTs) in Anti-de Sitter (AdS) spacetime are often
strongly coupled when the radius of AdS is large, and few methods are available
to study them. In this work, we develop a Hamiltonian truncation method to
compute the energy spectrum of QFTs in two-dimensional AdS. The infinite volume
of constant timeslices of AdS leads to divergences in the energy levels. We
propose a simple prescription to obtain finite physical energies and test it
with numerical diagonalization in several models: the free massive scalar
field, $\phi^4$ theory, Lee-Yang and Ising field theory. Along the way, we
discuss spontaneous symmetry breaking in AdS and derive a compact formula for
perturbation theory in quantum mechanics at arbitrary order. Our results
suggest that all conformal boundary conditions for a given theory are connected
via bulk renormalization group flows in AdS.
