40 citations · 242 across the 42 of their papers we have counts for
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When is a bosonic operator a Hamiltonian?
Felix Fischer, Hermann Schulz-Baldes, Daniel Burgarth +1
Hermitian polynomials in the quadrature operators and are the basic ingredients of continuous-variable quantum information, and increasingly exotic ones are now routinely e…
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…
Phenomenological quantum mechanics: II. Deducing the formalism from experimental observations
Piotr Szańkowski, Davide Lonigro, Fattah Sakuldee +2
We propose an exercise in which one attempts to deduce the formalism of quantum mechanics solely from phenomenological observations. The only assumed inputs are the multi-time prob…
Robust quantification of spectral transitions in perturbed quantum systems
Zsolt Szabó, Stefan Gehr, Paolo Facchi +3
A quantum system subject to an external perturbation can experience leakage between uncoupled regions of its energy spectrum separated by a gap. To quantify this phenomenon, we pre…
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…
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…
Quantifying the rotating-wave approximation of the Dicke model
Leonhard Richter, Daniel Burgarth, Davide Lonigro
We analytically find quantitative, non-perturbative bounds to the validity of the rotating-wave approximation (RWA) for the multi-atom generalization of the quantum Rabi model: the…
Phenomenological quantum mechanics: I. Phenomenology of quantum observables
Piotr Szańkowski, Davide Lonigro, Fattah Sakuldee +2
We propose an exercise in which one attempts to deduce the formalism of quantum mechanics solely from phenomenological observations. The only assumed inputs are obtained through se…
Efficiency of Dynamical Decoupling for (Almost) Any Spin-Boson Model
Alexander Hahn, Daniel Burgarth, Davide Lonigro
Dynamical decoupling is a technique aimed at suppressing the interaction between a quantum system and its environment by applying frequent unitary operations on the system alone. I…
On the Liouville-von Neumann equation for unbounded Hamiltonians
Davide Lonigro, Alexander Hahn, Daniel Burgarth
The evolution of mixed states of a closed quantum system is described by a group of evolution superoperators whose infinitesimal generator (the quantum Liouville superoperator, or…
Double or nothing: a Kolmogorov extension theorem for multitime (bi)probabilities in quantum mechanics
Davide Lonigro, Fattah Sakuldee, Łukasz Cywiński +2
The multitime probability distributions obtained by repeatedly probing a quantum system via the measurement of an observable generally violate Kolmogorov's consistency property. Th…
Positive Hamiltonians cannot give exponential decay of positive observables
Paolo Facchi, Davide Lonigro
The survival probability of a quantum system with a finite ground energy is known to decay subexponentially at large times. Here we show that, under the same assumption, the averag…
Dimensional reduction of the Dirac equation in arbitrary spatial dimensions
Davide Lonigro, Rocco Maggi, Giuliano Angelone +5
We investigate the general properties of the dimensional reduction of the Dirac theory, formulated in a Minkowski spacetime with an arbitrary number of spatial dimensions. This is…
On the classicality of quantum dephasing processes
Davide Lonigro, Dariusz Chruściński
We analyze the multitime statistics associated with pure dephasing systems repeatedly probed with sharp measurements, and search for measurement protocols whose statistics satisfie…
Dimensional reduction of the Dirac theory
Giuliano Angelone, Elisa Ercolessi, Paolo Facchi +5
We perform a reduction from three to two spatial dimensions of the physics of a spin-1/2 fermion coupled to the electromagnetic field, by applying Hadamard's method of descent. We…
On Markovianity and classicality in multilevel spin-boson models
Dariusz Chruściński, Samaneh Hesabi, Davide Lonigro
We provide a detailed discussion about the unitary and reduced evolution induced by family of Hamiltonian models describing a multilevel system, with a ground state and a possibly…
Excitation-damping quantum channels
Davide Lonigro, Dariusz Chruściński
We study a class of quantum channels describing a quantum system, split into the direct sum of an excited and a ground sector, undergoing a one-way transfer of population from the…
Quantum regression in dephasing phenomena
Davide Lonigro, Dariusz Chruściński
We investigate the validity of quantum regression for a family of quantum Hamiltonians on a multipartite system leading to phase-damping reduced dynamics. After finding necessary a…
Quantum regression beyond the Born-Markov approximation for generalized spin-boson models
Davide Lonigro, Dariusz Chruściński
The quantum regression formula for an open quantum system consists in an infinite hierarchy of conditions for its multi-time correlation functions, thus requiring full access to th…
Quantum magnetic billiards: boundary conditions and gauge transformations
Giuliano Angelone, Paolo Facchi, Davide Lonigro
We study admissible boundary conditions for a charged quantum particle in a two-dimensional region subjected to an external magnetic field, i.e. a quantum magnetic billiard. After…
Quantum non-Markovianity elusive to interventions
Daniel Burgarth, Paolo Facchi, Davide Lonigro +1
The non-Markovian nature of open quantum dynamics lies in the structure of the multitime correlations, which are accessible by means of interventions. Here, by examining multitime…
Stationary excitation waves and multimerization in arrays of quantum emitters
Davide Lonigro, Paolo Facchi, Saverio Pascazio +2
We explore the features of an equally-spaced array of two-level quantum emitters, that can be either natural atoms (or molecules) or artificial atoms, coupled to a field with a sin…
Photon-emitter dressed states in a closed waveguide
Davide Lonigro, Paolo Facchi, Andrew D. Greentree +3
We study a system made up of one or two two-level quantum emitters, coupled to a single transverse mode of a closed waveguide, in which photon wavenumbers and frequencies are discr…
Hidden non-Markovianity in open quantum systems
Daniel Burgarth, Paolo Facchi, Marilena Ligabò +1
We show that non-Markovian open quantum systems can exhibit exact Markovian dynamics up to an arbitrarily long time; the non-Markovianity of such systems is thus perfectly "hidden"…