14 papers
Self-adjoint extensions of -photon light-matter Hamiltonians
Felix Fischer, Felix Knapp, Daniel Burgarth +1
Multiphoton light-matter interactions, in which a bosonic mode exchanges excitations at a time with a quantum system, are a source of genuine nonlinearity in quantum optics and…
The Floquet-Magnus expansion of unbounded operators
Daniel Burgarth, Robin Hillier, Davide Lonigro +1
The Floquet-Magnus expansion is a widely used tool to derive effective descriptions of time-periodic quantum systems by approximating their dynamics with a time-independent Hamilto…
Essentially singular limits of Jacobi operators and applications to higher-order squeezing
Felix Fischer, Daniel Burgarth, Davide Lonigro
We study a family of Jacobi operators in which the diagonal entries are multiplied by a coupling parameter . Under suitable conditions, the operator is self-adjoint for ev…
Quantum particle in the wrong box (or: the perils of finite-dimensional approximations)
Felix Fischer, Daniel Burgarth, Davide Lonigro
When numerically simulating the unitary time evolution of an infinite-dimensional quantum system, one is usually led to treat the Hamiltonian as an "infinite-dimensional matrix…
Finite-dimensional approximations of generalized squeezing
Sahel Ashhab, Felix Fischer, Davide Lonigro +2
We show unexpected behaviour in simulations of generalized squeezing performed with finite-dimensional truncations of the Fock space: even for extremely large dimension of the stat…
Error bounds for the Floquet-Magnus expansion and their application to the semiclassical quantum Rabi model
Anirban Dey, Davide Lonigro, Kazuya Yuasa +1
We present a general, nonperturbative method for deriving effective Hamiltonians of arbitrary order for periodically driven systems, based on an iterated integration by parts techn…