arXiv subjects

Domenico Giuliano

Publications and source records attributed to Domenico Giuliano.

At least 19 recordsLinked to original sources

arXiv2026

Exact fluctuation relations in voltage- and temperature-biased Laughlin-edge constrictions

We present a comprehensive analysis of non-equilibrium fluctuation-dissipation relations connect- ing experimentally accessible chiral-current auto- and cross-correlations to the tunneling-current noise and conductance in Laughlin edge states coupled through a quantum point contact (QPC). We examine their validity for two chiral Laughlin edges held at different temperatures and voltages and show that the relations remain exact for arbitrary tunneling strength, voltage bias, and edge- state temperatures. We further generalize them to spatially extended QPCs and to tunneling am- plitudes with an explicit voltage dependence, and discuss the conditions and limitations associated with these generalizations. Our results establish that the local tunneling-current noise generated at the QPC can be reliably reconstructed from experimentally accessible auto- and cross-correlations measured downstream, providing a robust route to characterize non-equilibrium transport in chiral edge states.

cond-mat.mes-hall↗

arXiv2026

DC Conductance of X-shaped Majorana Interferometer reveals Non-Abelian Anyon Statistics

We propose a four-terminal, X-shaped chiral Majorana interferometer with a central floating superconducting island, enabling the direct detection of the non-Abelian statistics of Ising anyons via the linear-response DC conductance tensor in charge transport experiments. Here, Ising anyons are realizable as edge vortices nucleated at Josephson line junctions defining the superconducting island, where both edge-vortex and Majorana-fermion tunneling processes can occur. We show that in such a multi-terminal Majorana interferometer, both the vacuum and the fermionic fusion channel for Ising anyons are possible. This is in contrast to two-arm interferometers, where only the vacuum fusion channel is accessible and the DC conductance contribution from edge vortices always vanishes. Using a low-energy effective theory derived via chiral bosonization, we find that in the X-shaped interferometer, the DC conductance tensor is completely isotropic, yielding a non-zero conductance when simultaneous edge-vortex and Majorana tunneling activates the fermionic fusion channel. Apart from conductance oscillations in a gate-tunable charge parameter, which display an offset related to the anyon topological spin, measuring a finite conductance can already provide direct evidence for non-Abelian statistics in this geometry.

quant-ph↗

arXiv2026

Dissipation Mechanisms and Dissipative Phase Transitions of two coupled Fully Connected Quantum Ising models

We study dissipative phase transitions in a system of two coupled fully-connected quantum Ising models interacting with an environment. The dynamics is governed by a Lindblad master equation combining coherent unitary evolution and incoherent dissipative processes, where the unitary part is described within a self-consistent mean-field framework effectively acting on the local Hilbert space of two coupled spins at each site. We analyze two fundamentally different classes of dissipators. In the first case, the jump operators are defined in the instantaneous eigenbasis of the mean-field Hamiltonian and satisfy a detailed-balance condition. In this setting, the relaxation dynamics depends strongly on the quench protocol: a parametric quench of the Hamiltonian leads to conventional relaxation, whereas a temperature quench gives rise to a dynamical phase transition characterized by nonanalytic behavior in time. Yet, in both cases, the system relaxes toward a steady state determined solely by the post-quench parameters and the bath temperature, which closely resembles a thermal Gibbs state of the mean-field Hamiltonian. As a result, the dissipative phase transition occurs at a critical point consistent with the corresponding equilibrium transition. In contrast, when the dissipators are realized via local spin raising and lowering operators, the steady state is genuinely nonequilibrium, leading to a significantly richer phase diagram. In particular, for sufficiently strong system-bath coupling, we observe a reentrant phase featuring a symmetry-broken region bounded by two continuous dissipative phase transitions. Our results evidence how the structure of dissipative processes controls the emergence of equilibrium-like versus genuinely nonequilibrium critical behavior in open quantum systems.

cond-mat.stat-mech↗

arXiv2026

Post-quench relaxation dynamics of Gross-Neveu lattice fermions

We study the quantum relaxation dynamics for a lattice version of the one-dimensional (1D) $N$-flavor Gross-Neveu (GN) model after a Hamiltonian parameter quench. Allowing for a system-reservoir coupling $γ$, we numerically describe the system dynamics through a time-dependent self-consistent Lindblad master equation. For a closed ($γ=0$) finite-size system subjected to an interaction parameter quench, the order parameter dynamics exhibits oscillations and revivals. In the thermodynamic limit, our results imply that the order parameter reaches its post-quench stationary value in accordance with the eigenstate thermalization hypothesis (ETH). However, time-dependent finite-momentum correlation matrix elements equilibrate only if $γ>0$. Our findings are consistent with the system being described by a pertinent Generalized Gibbs Ensemble (GGE) and, accordingly, highlight subtle yet important aspects of the post-quench relaxation dynamics of quantum many-body systems.

cond-mat.stat-mech↗

arXiv2025

Speeding up Pontus-Mpemba effects via dynamical phase transitions

We demonstrate that open quantum systems exhibiting dynamical phase transitions (DPTs) allow for efficient protocols implementing the Pontus-Mpemba effect. The relaxation speed-up toward a predesignated target state is tied to the existence of a long metastable time window preceding the DPT and can be exploited in applications to systematically optimize quantum protocols. As paradigmatic example for the connection between DPTs and quantum Mpemba effects, we study one-dimensional (1D) interacting lattice fermions corresponding to a dissipative variant of the Gross-Neveu (GN) model.

quant-ph↗

arXiv2025

Spin and thermal current scaling at a $Y$-junction of XX spin chains

We study the boundary phase diagram and the low-temperature heat and magnetization transport at a $Y$-junction of XX spin chains. Depending on the magnetization axis anisotropy between the magnetic exchange interactions at the junction, the system exhibits two different strong-coupling regimes at low energies/temperatures, similar to the overscreened (topological) four- and to the two-channel Kondo fixed points. Using renormalization group arguments combined with boundary conformal field theory methods, we show the instability of the former under any XY-type anisotropy at the junction. We analyze the low-temperature spin and the heat conductances. We find evidence of spin fractionalization of the elementary excitations at the four-channel Kondo fixed point by means of the magnetic Wiedemann-Franz law. We caution that the instability under XY anisotropy may hinder the detection of the phenomenology related to the four-channel Kondo effect, therefore requiring careful control in experimental realizations.

cond-mat.str-el↗

arXiv2025

Charge current and phase diagram of the disordered open longer-range Kitaev chain

We compute the disorder averaged dc conductance in the non-equilibrium steady state that sets in between a longer-range Kitaev chain and a metallic lead connected to an external reservoir, as a function of the system parameters and of the disorder strength. From our results, we map out the phase diagram of the disordered chain for different types of disorder and discuss the corresponding effects of the interplay between topology and disorder in the system. To do so, we set up a combined analytical and numerical approach, which is potentially amenable of straightforward generalizations to other disordered topological systems.

cond-mat.str-el↗

arXiv2025

Phase diagram of the disordered Kitaev chain with long range pairing connected to external baths

We study the phase diagram of a disordered Kitaev chain with long-range pairing when connected to two metallic leads exchanging particles with external Lindblad baths. We (i) monitor the subgap modes at increasing disorder, (ii) compute the current flowing across the system at a finite voltage bias between the baths, and (iii) study the normal single particle lead correlations across the chain. Throughout our derivation, we evidence the interplay between disorder and topology. In particular, we evidence the reentrant behavior of the massive, topological phase at limited values of the disorder strength, similar to what happens in the short-range pairing Kitaev model. Our results suggest the possibility of a disorder-induced direct transition between the massive and the short-range topological phase of the long-range pairing Kitaev model.

cond-mat.str-el↗

arXiv2024

Can multipartite entanglement be characterized by two-point connected correlation functions ?

We discuss under which conditions multipartite entanglement in mixed quantum states can be characterized only in terms of two-point connected correlation functions, as it is the case for pure states. In turn, the latter correlations are defined via a suitable combination of (disconnected) one- and two-point correlation functions. In contrast to the case of pure states, conditions to be satisfied turn out to be rather severe. However, we were able to identify some interesting cases, as when the point-independence is valid of the one-point correlations in each possible decomposition of the density matrix, or when the operators that enter in the correlations are (semi-)positive/negative defined.

quant-ph↗

arXiv2024

Tunneling current and current correlations for anyonic quasiparticles of ν = 1/2 chiral Luttinger liquid in multi-edge geometries

We consider anyonic quasiparticles with charge e/2 described by the ν = 1/2 chiral Luttinger liquid, which collide in a Hong-Ou-Mandel-like interferometer. These colliding anyonic channels can be formally viewed as hosting Laughlin-like fractional ν = 1/2 quasiparticles. More specifically, two possible geometries are considered: (i) a two-edge-channel setup where anyons originate from equilibrium reservoirs; (ii) a four-edge-channel setup where nonequilibrium anyons arrive at the collider in the form of diluted beams. For both setups, we calculate the tunneling current and the current correlations. For setup (i), our results provide analytically exact expressions for the tunneling current, tunneling-current noise, and cross-correlation noise, The exact relation between conductance and noise is demonstrated. For setup (ii), we show that the tunneling current and the generalized Fano factor [defined in B. Rosenow et al. (2016)] are finite for diluted streams of ν = 1/2 anyons. This is due to the processes where nonequilibrium anyons, supplied via either source edge, directly tunnel at the central QPC. Thus, to obtain meaningful results in this case, one should go beyond the so-called time-domain braiding processes, where nonequilibrium anyons do not tunnel at the collider, but rather indirectly influence the tunneling by braiding with the quasiparticle-quasihole pairs created at the collider. This suggests that the effect of direct tunneling and collisions of diluted anyons in the Hong-Ou-Mandel interferometer can be important for various observables in physical quantum-Hall edges at Laughlin filling fractions.

cond-mat.mes-hall↗

arXiv2024

Non-Abelian anyon statistics through AC conductance of a Majorana interferometer

Demonstrating the non-Abelian Ising anyon statistics of Majorana zero modes in a physical platform still represents a major open challenge in physics. We here show that the linear low-frequency charge conductance of a Majorana interferometer containing a floating superconducting island can reveal the topological spin of quantum edge vortices. The latter are associated with chiral Majorana fermion edge modes and represent "flying" Ising anyons. We describe possible device implementations and outline how to detect non-Abelian anyon braiding through AC conductance measurements.

cond-mat.str-el↗

arXiv2024

Interfaces of nodal-line semimetals: drum states, transport and refraction

We study transport through interfaces in topological nodal-line semimetals, focusing on two geometries: a single interface between two large samples, one nodal-line semimetal and one metal, and an infinite nodal-line semimetal slab in between two metallic regions. We investigate the dependence of the spectra on the boundary conditions, showing how they affect the surface states and the band dispersion. We find a set of drum states, arising from the hybridization of the drumhead states on opposite surfaces at finite slab width, and describe their signatures in the transport properties of a clean sample. Finally, we compute the electronic trajectories in the ballistic regime and show that there is a series of resonant angles that ensure perfect transmission. We also show how the current density profile acquires an inhomogeneous distribution in the radial direction.

cond-mat.mes-hall↗

arXiv2024

The fate of high winding number topological phases in the disordered extended Su-Schrieffer-Heeger model

We use the Lindblad equation approach to investigate topological phases hosting more than one localized state at each side of a disordered SSH chain with properly tuned long range hoppings. Inducing a non equilibrium steady state across the chain, we probe the robustness of each phase and the fate of the edge modes looking at the distribution of electrons along the chain and the corresponding standard deviation in the presence of different kinds of disorder either preserving, or not, the symmetries of the Hamiltonian.

cond-mat.str-el↗

arXiv2024

Dissipation driven dynamical topological phase transitions in two-dimensional superconductors

We induce and study a topological dynamical phase transition between two planar superconducting phases. Using the Lindblad equation to account for the interactions of Bogoliubov quasiparticles among themselves and with the fluctuations of the superconducting order parameter, we derive the relaxation dynamics of the order parameter. To characterize the phase transition, we compute the fidelity and the spin-Hall conductance of the open system. Our approach provides crucial informations for experimental implementations, such as the dependence of the critical time on the system-bath coupling.

cond-mat.str-el↗

arXiv2023

Lindblad master equation approach to the dissipative quench dynamics of planar superconductors

We employ the Lindblad master equation method to study the nonequilibrium dynamics following a parametric quench in the Hamiltonian of an open, two-dimensional superconducting system coupled to an external bath. Within our approach we show how, in the open system, the dissipation works as an effective stabilization mechanism in the time evolution of the system after the quench. Eventually, we evidence how the mismatch between the phases corresponding to the initial and to the final state of the system determines a dynamical phase transition between the two distinct phases. Our method allows for fully characterizing the dynamical phase transition in an open system in several cases of physical relevance, by means of a combined study of the time-dependent superconducting gap and of the fidelity between density matrices.

cond-mat.str-el↗

arXiv2023

Spin-Hall Current and Nonlocal Transport in Ferromagnet-Free Multi-band models for SrTiO3-Based Nanodevices in the presence of impurities

We compute the spin-Hall conductance in a multiband model describing the two-dimensional electron gas formed at a LaAlO3/SrTiO3 interface in the presence of a finite concentration of impurities. Combining linear response theory with a systematic calculation of the impurity contributions to the self-energy, as well as to the vertex corrections of the relevant diagrams, we recover the full spin-Hall vs. sheet conductance dependence of LaAlO3/SrTiO3 as reported in Trier et al. [Nano Lett. 20, 395 (2020)], finding a very good agreement with the experimental data below and above the Lifshitz transition. In particular, we demonstrate that the multiband electronic structure leads to only a partial, instead of a complete, screening of the spin-Hall conductance, which decreases with increasing the carrier density. Our method can be generalized to other two-dimensional systems characterized by a broken inversion symmetry and multiband physics.

cond-mat.mes-hall↗

arXiv2023

Uniaxial modulation and the Berezinskii-Kosterlitz-Thouless transition

We present a theoretical study of the Berezinskii-Kosterlitz-Thouless transition of a two-dimensional superfluid in the presence of an externally imposed density modulation along a single axis. The subject is investigated in the context of the $|ψ|^4$ classical field theory, by means of analytical and numerical techniques. We show that, as the amplitude of the modulation increases, the physics of the system approaches that of the anisotropic $x$-$y$ model, with a suppressed superfluid transition temperature and an anisotropic response, but with no dimensional crossover.

cond-mat.stat-mech↗

arXiv2023

Understanding Traffic Jams Using Lindblad Superoperators

We propose a model to simulate different traffic-flow conditions in terms of quantum graphs hosting an (N+1)-level dot at each site. Our model allows us to keep track of the type and of the destination of each vehicle. The traffic flow inside the system is encoded in a proper set of Lindbladian local dissipators that describe the time evolution of the system density matrix. Taking advantage of the invariance of the Lindblad master equation under inhomogeneous transformations we derive the quantum Hamiltonian for the bulk dynamics in a proper experimental setup.

cond-mat.stat-mech↗