Momentum-resolved time evolution with matrix product states

We introduce a method based on matrix product states (MPS) for computing spectral functions of (quasi) one-dimensional spin chains, working directly in momentum space the thermodynamic limit. simulate time evolution after applying operator to an MPS ground state by with superposition window MPS. show explicitly spin-1 Heisenberg chain that growth entanglement is smaller space, even inside two-particle continuum, such we can attain very accurate relatively small bond dimension. apply our compute lineshapes gapless XXZ and square-lattice J1-J2 model six-leg cylinder.