SwePub - sökning: WFRF:(Jafari Rouhollah)

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1.	Naji, J., et al. (författare) Dissipative Floquet dynamical quantum phase transition 2022 Ingår i: PHYSICAL REVIEW A. - 2469-9926 .- 2469-9934. ; 105:2 Tidskriftsartikel (refereegranskat)abstract Non-Hermitian Hamiltonians provide a simple picture for inspecting dissipative systems with natural or induced gain and loss. We investigate the Floquet dynamical phase transition in the dissipative periodically time-driven XY and extended XY models, where the imaginary terms represent the physical gain and loss during the interacting processes with the environment. The time-independent effective Floquet non-Hermitian Hamiltonians disclose three regions by analyzing the non-Hermitian gap: pure real gap (real eigenvalues), pure imaginary gap, and complex gap. We show that each region of the system can be distinguished by the complex geometrical nonadiabatic phase. We have discovered that in the presence of dissipation, the Floquet dynamical phase transitions (FDPTs) still exist in the region where the time-independent effective Floquet non-Hermitian Hamiltonians reveal real eigenvalues. Opposed to expectations based on earlier works on quenched systems, our findings show that the existence of the non-Hermitian topological phase is not an essential condition for dissipative FDPTs (DFDPTs). We also demonstrate the range of driven frequency, over which the DFDPTs occur, narrows down by increasing the dissipation coupling and shrinks to a single point at the critical value of dissipation. Moreover, quantization and jumps of the dynamical geometric phase reveals the topological characteristic feature of DFDPTs in the real gap region where confined to exceptional points.
2.	Ansari, Saeid, et al. (författare) Dynamics of steered quantum coherence and magic resource under sudden quench 2024 Ingår i: QUANTUM INFORMATION PROCESSING. - 1570-0755 .- 1573-1332. ; 23:6 Tidskriftsartikel (refereegranskat)abstract We explore the dynamics of l1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l_1$$\end{document}-norm of steered quantum coherence (SQC), steered quantum relative entropy (SQRE), and magic resource quantifier (MRQ) in the one-dimensional XY spin chain in the presence of time-dependent transverse magnetic field. We find that the system's response is highly sensitive to the initial state and magnetic field strength. We show the dynamics of SQC, SQRE, and MRQ revealing the critical point associated with equilibrium quantum phase transition (QPT) of the system. All quantities show maximum at QPT when the initial state is prepared in the ferromagnetic phase. Conversely, they undergo abrupt changes at quantum critical point if the initial state of the system is paramagnetic. Moreover, our results confirm that when quench is done to the quantum critical point, the first suppression (revival) time scales linearly with the system size, and remarkably, its scaling ratio remains consistent for all quenches, irrespective of the initial phase of the system. These results highlight the interplay between the quantum information resources and dynamics of quantum systems away from the equilibrium. Such insights could be vital for quantum information processing and understanding non-equilibrium phenomena in quantum many-body systems.
3.	Baghran, R., et al. (författare) Competition of long-range interactions and noise at a ramped quench dynamical quantum phase transition: The case of the long-range pairing Kitaev chain 2024 Ingår i: PHYSICAL REVIEW B. - 2469-9950 .- 2469-9969. ; 110:6 Tidskriftsartikel (refereegranskat)abstract The nonequilibrium dynamics of long-range pairing Kitaev model with noiseless/noisy linear time dependent chemical potential, is investigated in the framework of dynamical quantum phase transitions (DQPTs). We have shown that for the ramp crossing a single quantum critical point, while the short-range pairing Kitaev model displays a single critical time scale, the long-range pairing induces a region with three DQPTs time scales. We have found that the region with three DQPTs time scales shrinks in the presence of the noise. In addition, we have uncovered that for a quench crossing two critical points, the critical sweep velocity above which the DQPTs disappear enhances by the long-range pairing exponent while decreases in the presence of the noise. On the basis of numerical simulations, we have shown that noise diminishes the long-range pairing inductions.
4.	Jafari, Rouhollah, et al. (författare) Decoherence from spin environments: Loschmidt echo and quasiparticle excitations 2017 Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 96 Tidskriftsartikel (refereegranskat)abstract © 2017 American Physical Society. We revisit the problem of decoherence of a qubit centrally coupled to an interacting spin environment, here modeled by a quantum compass chain or an extended XY model in a staggered magnetic field. These two models both support distinct spin-liquid phases, adding a new element to the problem. By analyzing their Loschmidt echoes when perturbed by the qubit we find that a fast decoherence of the qubit is conditioned on the presence of propagating quasiparticles which couple to it. Differently from expectations based on earlier works on central spin models, our result implies that the closeness of an environment to a quantum phase transition is neither a sufficient nor a necessary condition for an accelerated decoherence rate of a qubit.
5.	Jafari, Rouhollah (författare) Dynamical Quantum Phase Transition and Quasi Particle Excitation 2019 Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9 Tidskriftsartikel (refereegranskat)abstract Dynamical phase transitions (DPTs) are signaled by the non-analytical time evolution of the dynamical free energy after quenching some global parameters in quantum systems. The dynamical free energy is calculated from the overlap between the initial and the time evolved states (Loschmidt amplitude). In a recent study it was suggested that DPTs are related to the equilibrium phase transitions (EPTs) (Heyl, M. et al. Phys. Rev. Lett. 110, 135704 (2013)). We here study an exactly solvable model, the extended XY model, the Loschmidt amplitude of which provides a counterexample. We show analytically that the connection between the DPTs and the EPTs does not hold generally. Analysing also the general compass model as a second example, assists us to propound the physical condition under which the DPT occurs without crossing the equilibrium critical point, and also no DPT by crossing the equilibrium critical point.
6.	Jafari, Rouhollah, et al. (författare) Dynamical quantum phase transitions following a noisy quench 2024 Ingår i: PHYSICAL REVIEW B. - 2469-9950 .- 2469-9969. ; 109:18 Tidskriftsartikel (refereegranskat)abstract We study how time -dependent energy fluctuations impact the dynamical quantum phase transitions (DQPTs) following a noisy ramped quench of the transverse magnetic field in a quantum Ising chain. By numerically solving the stochastic Schr & ouml;dinger equation of the mode-decoupled fermionic Hamiltonian of the problem, we identify two generic scenarios: Depending on the amplitude of the noise and the rate of the ramp, the expected periodic sequence of noiseless DQPTs may either be uniformly shifted in time or else replaced by a disarray of closely spaced DQPTs. Guided by an exact noise master equation, we trace the phenomenon to the interplay between noise -induced excitations which accumulate during the quench and the near -adiabatic dynamics of the massive modes of the system. Our analysis generalizes to any one-dimensional fermionic two -band model subject to a noisy quench.
7.	Jafari, Rouhollah, et al. (författare) Dynamics of quantum coherence and quantum Fisher information after a sudden quench 2020 Ingår i: Physical Review A. - 2469-9926. ; 101:6 Tidskriftsartikel (refereegranskat)abstract The dynamics of relative entropy and l1 norm of coherence, as well as, the Wigner-Yanase skew and quantum Fisher information are studied in the one-dimensional XY spin chain in the presence of a time-dependent transverse magnetic field. We show that, independent of the initial state of the system and while the relative entropy of coherence, the l1 norm of coherence, and quantum Fisher information are incapable, surprisingly, the Wigner-Yanase skew information dynamic can truly spotlight the equilibrium critical point. We also observe that, when the system is quenched to the critical point, these quantities show suppressions and revivals. Moreover, the first suppression (revival) time scales linearly with the system size and its scaling ratio is unique for all quenches independent of the initial phase of the system. This is the promised universality of the first suppression (revival) time. © 2020 American Physical Society.
8.	Jafari, Rouhollah, et al. (författare) Floquet dynamical phase transition and entanglement spectrum 2021 Ingår i: Physical Review A. - 2469-9926. ; 103:1 Tidskriftsartikel (refereegranskat)abstract We explore both pure and mixed state Floquet dynamical quantum phase transitions (FDQFTs) in the one-dimensional p-wave superconductor with a time-driven pairing phase. In the Fourier space the model is recast to the noninteracting quasispins subjected to a time-dependent effective magnetic field. We show that FDQFTs occur within a range of driving frequency without resorting to any quenches. Moreover, FDQFTs appear in the region where quasispins are in the resonance regime. In the resonance regime, the population completely cycles the population between the spin down and up states. Additionally, we study the conditions for the appearance of FDQFTs using the entanglement spectrum and purity entanglement measure. Our results imply that the entanglement spectrum can truly capture the resonance regime where FDQFTs occur. Particularly, the dynamical topological region results in the degeneracy of the entanglement spectrum. It is shown that the boundary of the driven frequency range, over which the system reveals FDQFTs, is signaled by the purity entanglement measure.
9.	Jafari, Rouhollah, et al. (författare) Floquet dynamical quantum phase transitions under synchronized periodic driving 2022 Ingår i: Physical Review B. - 2469-9950. ; 105:9 Tidskriftsartikel (refereegranskat)abstract We study a generic class of fermionic two-band models under synchronized periodic driving, i.e., with the different terms in a Hamiltonian subject to periodic drives with the same frequency and phase. With all modes initially in a maximally mixed state, the synchronized drive is found to produce nonperiodic patterns of dynamical quantum phase transitions, with their appearance determined by an interplay of the band structure and the frequency of the drive. A case study of the anisotropic XY chain in a transverse magnetic field, transcribed to an effective two-band model, shows that the modes come with quantized geometric phases, allowing for the construction of an effective dynamical order parameter. Numerical studies in the limit of a strong magnetic field reveal distinct signals of precursors of dynamical quantum phase transitions also when the initial state of the XY chain is perturbed slightly away from maximal mixing, suggesting that the transitions may be accessible experimentally. A blueprint for an experiment built around laser-trapped circular Rydberg atoms is proposed.
10.	Jafari, Rouhollah, et al. (författare) Geometrically frustrated anisotropic four-leg spin-1/2 nanotube 2019 Ingår i: Journal of Physics-Condensed Matter. - 0953-8984. ; 31:49 Tidskriftsartikel (refereegranskat)abstract We develop a real space quantum renormalization group (QRG) to explore a frustrated anisotropic four-leg spin-1/2 nanotube in the thermodynamic limit. We obtain the phase diagram, fixed points, critical points, the scaling of coupling constants and magnetization curves. Our investigation points out that, in the case of strong leg coupling, the diagonal frustrating interaction is marginal under QRG transformations and does not affect the universality class of the model. Remarkably, the renormalization equations express that the spin nanotube prepared in the strong leg coupling case goes to the strong plaquette coupling limit (weakly interacting plaquettes). Subsequently, in the limit of weakly interacting plaquettes, the model is mapped onto a 1D spin-1/2 XXZ chain in a longitudinal magnetic field under QRG transformation. Furthermore, the effective Hamiltonian of the spin nanotube inspires both first and second order phase transitions accompanied by the fractional magnetization plateaus. Our results show that the anisotropy changes the magnetization curve and the phase transition points, significantly. Finally, we report the numerical exact diagonalization results to compare the ground state phase diagram with our analytical visions.
11.	Jafari, Rouhollah, et al. (författare) Loschmidt Echo Revivals: Critical and Noncritical 2017 Ingår i: Physical Review Letters. - 0031-9007. ; 118:1 Tidskriftsartikel (refereegranskat)abstract A quantum phase transition is generally thought to imprint distinctive characteristics on the non-equilibrium dynamics of a closed quantum system. Specifically, the Loschmidt echo after a sudden quench to a quantum critical point-measuring the time dependence of the overlap between initial and time-evolved states-is expected to exhibit an accelerated relaxation followed by periodic revivals. We here introduce a new exactly solvable model, the extended Su-Schrieffer-Heeger model, the Loschmidt echo of which provides a counterexample. A parallell analysis of the quench dynamics of the three-site spin-interacting XY model allows us to pinpoint the conditions under which a periodic Loschmidt revival actually appears.
12.	Jafari, Rouhollah (författare) Quench dynamics and ground state fidelity of the one-dimensional extended quantum compass model in a transverse field 2016 Ingår i: Journal of Physics a-Mathematical and Theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 49:18 Tidskriftsartikel (refereegranskat)abstract We study the ground state fidelity, fidelity susceptibility, and quench dynamics of the extended quantum compass model in a transverse field. This model reveals a rich phase diagram which includes several critical surfaces depending on exchange couplings. We present a characterization of quantum phase transitions in terms of the ground state fidelity between two ground states obtained for two different values of external parameters. We also derive scaling relations describing the singular behavior of the fidelity susceptibility in the quantum critical surfaces. Moreover, we study the time evolution of the system after a critical quantum quench using the Loschmidt echo (LE). We find that the revival times of LE are given byT(rev) = N2 nu(max), where N is the size of the system and v(max) is the maximum of the lower bound group velocity of quasi-particles. Although the fidelity susceptibility shows the same exponent in all critical surfaces, the structure of the revivals after critical quantum quenches displays two different regimes reflecting different equilibration dynamics.
13.	Jafari, Rouhollah, et al. (författare) Quench dynamics and zero-energy modes: The case of the Creutz model 2019 Ingår i: Physical Review B. - 2469-9950. ; 99:5 Tidskriftsartikel (refereegranskat)abstract In most lattice models, the closing of a band gap typically occurs at high-symmetry points in the Brillouin zone. Differently, in the Creutz model-describing a system of spinless fermions hopping on a two-leg ladder pierced by a magnetic field-the gap closing at the quantum phase transition between the two topologically nontrivial phases of the model can be moved by tuning the hopping amplitudes. We take advantage of this property to examine the nonequilibrium dynamics of the model after a sudden quench of the magnetic flux through the plaquettes of the ladder. For a quench to one of the equilibrium quantum critical points, we find that the revival period of the Loschmidt echo-measuring the overlap between initial and time-evolved states-is controlled by the gap closing zero-energy modes. In particular, and contrary to expectations, the revival period of the Loschmidt echo for a finite ladder does not scale linearly with size but exhibits jumps determined by the presence or absence of zero-energy modes. We further investigate the conditions for the appearance of dynamical quantum phase transitions in the model and find that, for a quench to an equilibrium critical point, such transitions occur only for ladders of sizes which host zero-energy modes. Exploiting concepts from quantum thermodynamics, we show that the average work and the irreversible work per lattice site exhibit a weak dependence on the size of the system after a quench across an equilibrium critical point, suggesting that quenching into a different phase induces effective correlations among the particles.
14.	Jafari, Rouhollah, et al. (författare) Real Space Renormalization of Majorana Fermions in Quantum Nano-Wire Superconductors 2017 Ingår i: Journal of the Physical Society of Japan. - : Physical Society of Japan. - 0031-9015 .- 1347-4073. ; 86:2 Tidskriftsartikel (refereegranskat)abstract We develop the real space quantum renormalization group (QRG) approach for majorana fermions. As an example we focus on the Kitaev chain to investigate the topological quantum phase transition (TQPT) in the one-dimensional spinless p-wave superconductor. Studying the behaviour of local compressibility and ground-state fidelity, show that the TQPT is signalled by the maximum of local compressibility at the quantum critical point tuned by the chemical potential. Moreover, a sudden drop of the ground-state fidelity and the divergence of fidelity susceptibility at the topological quantum critical point are used as proper indicators for the TQPT, which signals the appearance of Majorana fermions. Finally, we present the scaling analysis of ground-state fidelity near the critical point that manifests the universal information about the TQPT, which reveals two different scaling behaviors as we approach the critical point and thermodynamic limit.
15.	Mahdavifar, Salimeh, et al. (författare) Magnetic quantum correlations in the one-dimensional transverse-field XXZ model 2017 Ingår i: Physical Review A. - 2469-9926. ; 96:5 Tidskriftsartikel (refereegranskat)abstract One-dimensional spin-1/2 systems are well-known candidates to study the quantum correlations between particles. In condensed matter physics, studies often are restricted to first-neighbor particles. In this work, we consider the one-dimensional XXZ model in a transverse magnetic field (TF) which is not integrable except at specific points. Analytical expressions for quantum correlations (entanglement and quantum discord) between spin pairs at any distance are obtained for both zero and finite temperature by using the analytical approach proposed by Caux et al. [Phys. Rev. B 68, 134431 (2003)]. We compare the efficiency of the quantum discord (QD) with respect to the entanglement in the detection of critical points as the neighboring spin pairs go farther than the next-nearest neighbors. In the absence of the TF and at zero temperature, we show that the QD for spin pairs farther than the second neighbors is able to capture the critical points while the pairwise entanglement is absent. In contrast with the pairwise entanglement, two-site QD is effectively long range in the critical regimes where it decays algebraically with the distance between pairs. We also show that the thermal QD between neighbor spins possesses strong distinctive behavior at the critical point that can be seen at finite temperature and, therefore, spotlights the critical point while the entanglement fails in this task.
16.	Mishra, Utkarsh, et al. (författare) Disordered Kitaev chain with long-range pairing: Loschmidt echo revivals and dynamical phase transitions 2020 Ingår i: JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 53:37 Tidskriftsartikel (refereegranskat)abstract We explore the dynamics of long-range Kitaev chain by varying pairing interaction exponent. It is well known that the distinctive features of the nonequilibrium dynamics of a closed quantum system are closely related to the equilibrium phase transitions. Specifically, the return probability (Loschmidt echo) of the system to its initial state, in the finite-size system, is expected to exhibit periodicity after a sudden quench to a quantum critical point. The time of the first revivals scales inversely with the maximum of the group velocity. We show that, contrary to expectations, the periodicity of the return probability breaks for a sudden quench to the non-trivial quantum critical point. Further, we find that the periodicity of the return probability scales inversely with the group velocity at the gap closing point for a quench to the trivial critical point of truly long-range pairing case. Also, analyzing the effect of averaging quenched disorder shows that the revivals in the short-range pairing cases are more robust against disorder than that of the long-range pairing case. We also study the effect of disorder on the non-analyticities of the rate function of the return probability which introduced as a witness of the dynamical phase transition. We show that the non-analyticities in the rate function of return probability are washed out in the presence of strong disorders.
17.	Mishra, U., et al. (författare) Dynamical quantum correlations after sudden quenches 2018 Ingår i: Physical Review A. - 2469-9926. ; 98:5 Tidskriftsartikel (refereegranskat)abstract We employ the mean-field approach in the fermionic picture of the spin-1/2 XXZ chain to investigate the dynamics of bipartite quantum discord and concurrence under sudden quenching. In this case, when quenching is performed in the anisotropy from an initial value to the critical point, the quantum correlations show periodic cusps in time. Moreover, the first suppression (cusp) in quantum correlations can be explained in terms of the semiclassical picture of quasiparticle propagation. On the other hand, quenching to, as well as away from, the criticality point shows that the long time pairwise quantum discord gets enhanced from its initial state. Finally, we show that, in the gapped region, a quench in the transverse field displays survival of the next-nearest-neighbor quantum discord. Our results provide a further insight into the dynamical behavior of quantum correlations and their connections to quantum criticality.
18.	Naji, J., et al. (författare) Engineering Floquet dynamical quantum phase transitions 2022 Ingår i: Physical Review B. - 2469-9950. ; 106:9 Tidskriftsartikel (refereegranskat)abstract Floquet dynamical quantum phase transitions (FDQPTs) are signified by recurrent nonanalytic behaviors of observables in time. In this work, we introduce a quench-free and generic approach to engineer and control FDQPTs for both pure and mixed Floquet states. By applying time-periodic modulations with two driving frequencies to a general class of spin chain model, we find multiple FDQPTs within each driving period. The model is investigated with equal, commensurate and incommensurate driving frequencies. The nonanalytic cusps of return probability form sublattice structures in time domain. Notably, the number and time locations of these cusps can be flexibly controlled by tuning the Hamiltonian parameter and the frequencies of the drive. We further employ the dynamical topological order parameter, which shows a quantized jump whenever a DQPT happens, to identify the topological feature of FDQPTs. Our findings reveal the advantage of engineering nonequilibrium phase transitions with multifrequency driving fields.
19.	Sadrzadeh, M., et al. (författare) Dynamical topological quantum phase transitions at criticality 2021 Ingår i: Physical Review B. - 2469-9950. ; 103:14 Tidskriftsartikel (refereegranskat)abstract The nonequilibrium dynamics of two-dimensional Su-Schrieffer-Heeger model, in the presence of staggered chemical potential, is investigated using the notion of dynamical quantum phase transition. We contribute to expanding the systematic understanding of the interrelation between the equilibrium quantum phase transition and the dynamical quantum phase transition (DQPT). Specifically, we find that dynamical quantum phase transition relies on the existence of massless propagating quasiparticles as signaled by their impact on the Loschmidt overlap. These massless excitations are a subset of all gapless modes, which leads to quantum phase transitions. The underlying two-dimensional model reveals gapless modes, which do not couple to the dynamical quantum phase transitions, while relevant massless quasiparticles present periodic nonanalytic signatures on the Loschmidt amplitude. The topological nature of DQPT is verified by the quantized integer values of the topological order parameter, which gets even values. Moreover, we have shown that the dynamical topological order parameter truly captures the topological phase transition on the zero Berry curvature line, where the Chern number is zero and the two-dimensional Zak phase is not the proper indicator.
20.	Uhrich, P., et al. (författare) Out-of-equilibrium phase diagram of long-range superconductors 2020 Ingår i: Physical Review B. - 2469-9950. ; 101:24 Tidskriftsartikel (refereegranskat)abstract Within the ultimate goal of classifying universality in quantum many-body dynamics, understanding the relation between out-of-equilibrium and equilibrium criticality is a crucial objective. Models with power-law interactions exhibit rich well-understood critical behavior in equilibrium, but the out-of-equilibrium picture has remained incomplete, despite recent experimental progress. We construct the rich dynamical phase diagram of free-fermionic chains with power-law hopping and pairing and provide analytic and numerical evidence showing a direct connection between nonanalyticities of the return rate and zero crossings of the string order parameter. Our results may explain the experimental observation of so-called accidental dynamical vortices, which appear for quenches within the same topological phase of the Haldane model, as reported by Flaschner et al. [Nat. Phys. 14, 265 (2018)]. Our work is readily applicable to modern ultracold-atom experiments, not least because state-of-the-art quantum gas microscopes can now reliably measure the string order parameter, which, as we show, can serve as an indicator of dynamical criticality.
21.	Zamani, S., et al. (författare) Floquet dynamical quantum phase transition in the extended XY model: Nonadiabatic to adiabatic topological transition 2020 Ingår i: Physical Review B. - 2469-9950. ; 102:14 Tidskriftsartikel (refereegranskat)abstract We investigate both pure and mixed states Floquet dynamical quantum phase transition (DQPT) in the periodically time-dependent extended XY model. We exactly show that the proposed Floquet Hamiltonian of interacting spins can be expressed as a sum of noninteracting quasispins imposed by an effective time dependent magnetic field (Schwinger-Rabi model). The calculated Chern number indicates that there is a topological transition from the nonadiabatic to adiabatic regime. In the adiabatic regime, the quasispins trace the time dependent effective magnetic field and then oscillate between spin up and down states. While in the nonadiabatic regime, the quasispins cannot follow the time dependent effective magnetic field and feel an average magnetic field. We find the range of driving frequency over which the quasispins experience adiabatic cyclic processes. Moreover, we obtain the exact expression of the Loschmidt amplitude and generalized Loschmidt amplitude of the proposed Floquet system. The results represent that both pure and mixed states dynamical phase transition occurs when the system evolves adiabatically. In other words, the minimum required driving frequency for the appearance of Floquet DQPT is equal to the threshold frequency needed for transition from the nonadiabatic to adiabatic regime. © 2020 American Physical Society.
22.	Zamani, S., et al. (författare) Out-of-time-order correlations and Floquet dynamical quantum phase transition 2022 Ingår i: Physical Review B. - 2469-9950. ; 105:9 Tidskriftsartikel (refereegranskat)abstract Out-of-time-order correlators (OTOCs) progressively play an important role in different fields of physics, particularly in the nonequilibrium quantum many-body systems. In this paper, we show that OTOCs can be used to probe the Floquet dynamical quantum phase transitions (FDQPTs). We investigate the OTOCs of two exactly solvable Floquet spin models, namely, Floquet XY chain and synchronized Floquet XY model. We show that the border of driving frequency range, over which the Floquet XY model shows FDQPT, is signaled by the global minimum of the infinite-temperature time averaged OTOC. Moreover, our results manifest that OTOCs decay algebraically in the long time, for which the decay exponent in the FDQPT region is different from that in the region where the system does not show FDQPTs. In addition, for the synchronized Floquet XY model, which reveals FDQPT at any driving frequency depending on the initial infinite or finite temperature, the imaginary part of the OTOCs becomes zero whenever the system shows FDQPT.
23.	Zamani, Sara, et al. (författare) Scaling and universality at ramped quench dynamical quantum phase transitions 2024 Ingår i: JOURNAL OF PHYSICS-CONDENSED MATTER. - 0953-8984 .- 1361-648X. ; 36:35 Tidskriftsartikel (refereegranskat)abstract The nonequilibrium dynamics of a periodically driven extended XY model, in the presence of linear time dependent magnetic field, is investigated using the notion of dynamical quantum phase transitions (DQPTs). Along the similar lines to the equilibrium phase transition, the main purpose of this work is to search fundamental concepts such as scaling and universality at the ramped quench DQPTs. We have shown that the critical points of the model, where the gap closing occurs, can be moved by tuning the driven frequency and consequently the presence of or absence of DQPTs can be flexibly controlled by adjusting the driven frequency. We have uncovered that, for a ramp across the single quantum critical point, the critical mode at which DQPTs occur is classified into three regions: the Kibble-Zurek (KZ) region, where the critical mode scales linearly with the square root of the sweep velocity, the pre-saturated (PS) region, and the saturated (S) region where the critical mode makes a plateau versus the sweep velocity. While for a ramp that crosses two critical points, the critical modes disclose just the KZ and PS regions. On the basis of numerical simulations, we find that the dynamical free energy scales linearly with time, as approaches to DQPT time, with the exponent nu = 1 +/- 0.01 for all sweep velocities and driven frequencies.

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