Superradiant Quantum Phase Transition for an Exactly Solvable Two-Qubit Spin-Boson Model

R Grimaudo, D Valenti, A Sergi, A Messina - Entropy, 2023 - mdpi.com
A spin-boson-like model with two interacting qubits is analysed. The model turns out to be
exactly solvable since it is characterized by the exchange symmetry between the two spins …

Analytically solvable Hamiltonian in invariant subspaces

ASM de Castro, R Grimaudo, D Valenti… - The European Physical …, 2023 - Springer
We study a generic time-dependent Jaynes–Cummings model, discovering universal
features of its time evolution on a dynamical time scale which is here defined as an integral …

Two-qubit entanglement generation through non-Hermitian Hamiltonians induced by repeated measurements on an ancilla

R Grimaudo, A Messina, A Sergi, NV Vitanov… - Entropy, 2020 - mdpi.com
In contrast to classical systems, actual implementation of non-Hermitian Hamiltonian
dynamics for quantum systems is a challenge because the processes of energy gain and …

Experimental investigation of state distinguishability in parity-time symmetric quantum dynamics

YT Wang, ZP Li, S Yu, ZJ Ke, W Liu, Y Meng… - Physical Review Letters, 2020 - APS
Comprehensive study on parity-time (PT) symmetric systems demonstrates the novel
properties and innovative application of non-Hermitian physics in recent years. In the …

Dzyaloshinskii-Moriya and dipole-dipole interactions affect coupling-based Landau-Majorana-Stückelberg-Zener transitions

R Grimaudo, H Nakazato, A Messina, NV Vitanov - Physical Review Research, 2020 - APS
It has been theoretically demonstrated that two spins (qubits or qutrits), coupled by
exchange interaction only, undergo a coupling-based joint Landau-Majorana-Stückelberg …

Spin‐Chain‐Star Systems: Entangling Multiple Chains of Spin Qubits

R Grimaudo, AS Magalhães de Castro… - Fortschritte der …, 2022 - Wiley Online Library
We consider spin‐chain‐star systems characterized by N‐wise many‐body interactions
between the spins in each chain and the central one. We show that such systems can be …

Dynamics of a harmonic oscillator coupled with a Glauber amplifier

R Grimaudo, VI Man'Ko, MA Man'Ko… - Physica Scripta, 2019 - iopscience.iop.org
A system of a quantum harmonic oscillator bi-linearly coupled with a Glauber amplifier is
analysed considering a time-dependent Hamiltonian model. The Hilbert space of this system …

Invariant-Parameterized Exact Evolution Operator for SU(2) Systems with Time-Dependent Hamiltonian

H Nakazato, A Sergi, A Migliore, A Messina - Entropy, 2023 - mdpi.com
We report the step-by-step construction of the exact, closed and explicit expression for the
evolution operator U (t) of a localized and isolated qubit in an arbitrary time-dependent field …

Thermodynamic limit in the two-qubit quantum Rabi model with spin-spin coupling

R Grimaudo, G Falci, A Messina, E Paladino… - arXiv preprint arXiv …, 2023 - arxiv.org
The occurrence of a second-order superradiant quantum phase transition is brought to light
in a quantum system consisting of two interacting qubits coupled to the same quantized field …

Characterization of Quantum and Classical Critical Points for an Integrable Two-Qubit Spin–Boson Model

R Grimaudo, A Messina, H Nakazato, A Sergi… - Symmetry, 2023 - mdpi.com
The class of two-interacting-qubit spin–boson models with vanishing transverse fields on the
spin-pair is studied. The model can be mapped exactly into two independent standard single …