▎ 摘　　要

A fast split operator method for computing time-dependent quantum states in bilayer graphene in a magnetic field is developed. The method is about an order of magnitude faster than the existing split operator method. It can also be used to compute time-dependent states in monolayer graphene and other systems with a Hamiltonian that depends linearly on momentum. The new method is based on an operator splitting that reduces the cubic order local error that appears in any split operator approximation to the evolution operator. The reduced error allows a larger time step to be used and hence reduces computational cost. The computational cost and accuracy of the existing and new split operator methods are analysed for the test problem of computing the motion of a Landau wave packet in bilayer graphene in crossed electric and magnetic fields. A comparison with the Chebyshev polynomial method is also given.