Large-order perturbation theory for a non-Hermitian 𝓟𝓣-symmetric Hamiltonian
Large-order perturbation theory for a non-Hermitian 𝓟𝓣-symmetric Hamiltonian
A precise calculation of the ground-state energy of the complex 𝒫𝒯-symmetric Hamiltonian H=p2+14x2+iλx3, is performed using high-order Rayleigh–Schrödinger perturbation theory. The energy spectrum of this Hamiltonian has recently been shown to be real using numerical methods. Here we present convincing numerical evidence that the Rayleigh–Schrödinger perturbation series is Borel summable, …