arXiv subjects

Xue-Jia Yu

Publications and source records attributed to Xue-Jia Yu.

At least 37 records · Page 2Linked to original sources

arXiv2025

Exploring nontrivial topology at quantum criticality in a superconducting processor

The discovery of nontrivial topology in quantum critical states has introduced a new paradigm for classifying quantum phase transitions and challenges the conventional belief that topological phases are typically associated with a bulk energy gap. However, realizing and characterizing such topologically nontrivial quantum critical states with large particle numbers remains an outstanding experimental challenge in statistical and condensed matter physics. Programmable quantum processors can directly prepare and manipulate exotic quantum many-body states, offering a powerful path for exploring the physics behind these states. Here, we present an experimental exploration of the critical cluster Ising model by preparing its low-lying critical states on a superconducting processor with up to $100$ qubits. We develop an efficient method to probe the boundary $g$-function based on prepared low-energy states, which allows us to uniquely identify the nontrivial topology of the critical systems under study. Furthermore, by adapting the entanglement Hamiltonian tomography technique, we recognize two-fold topological degeneracy in the entanglement spectrum under periodic boundary condition, experimentally verifying the universal bulk-boundary correspondence in topological critical systems. Our results demonstrate the low-lying critical states as useful quantum resources for investigating the interplay between topology and quantum criticality.

quant-ph↗

arXiv2025

Gapless Symmetry-Protected Topological States in Measurement-Only Circuits

Measurement-only quantum circuits offer a versatile platform for realizing intriguing quantum phases of matter. However, gapless symmetry-protected topological (gSPT) states remain insufficiently explored in these settings. In this Letter, we generalize the notion of gSPT to the critical steady state by investigating measurement-only circuits. Using large-scale Clifford circuit simulations, we investigate the steady-state phase diagram across several families of measurement-only circuits that exhibit topological nontrivial edge states at criticality. In the Ising cluster circuits, we uncover a symmetry-enriched non-unitary critical point, termed symmetry-enriched percolation, characterized by both topologically nontrivial edge states and string operator. Additionally, we demonstrate the realization of a steady-state gSPT phase in a $\mathbb Z_4$ circuit model. This phase features topological edge modes and persists within steady-state critical phases under symmetry-preserving perturbations. Furthermore, we provide a unified theoretical framework by mapping the system to the Majorana loop model, offering deeper insights into the underlying mechanisms.

cond-mat.str-el↗

arXiv2024

Topological edge states at Floquet quantum criticality

Topologically protected edge states exactly at topological phase boundaries challenge the conventional belief that topological states must be associated with a bulk energy gap. Because periodically driven (Floquet) systems host unusually intricate topological phase boundaries, topological edge states can be prolific at such Floquet quantum criticality. Working on a class of chiral-symmetric, Floquet-driven Majorana fermion chains, we analytically and computationally show that the precise boundaries between different Floquet topological gapped phases can accommodate topological edge modes, including the so-called Majorana $π$ modes. We also identify a general bulk-edge correspondence formula to predict and understand the emergence of topological edge modes at Floquet quantum criticality. Of direct interest to quantum simulation experiments, our results break new grounds for studies of nonequilibrium topological phases of matter undergoing topological phase transitions.

cond-mat.stat-mech↗

arXiv2024

Emergent dynamical quantum phase transition in a $Z_3$ symmetric chiral clock model

We study the quench dynamics in a $Z_3$ symmetric chiral clock model (CCM). The results reveal that chiral phases can lead to the emergence of dynamical quantum phase transition (DQPT). By analyzing Lee-Yang-Fisher zeros' distribution in the complex plane, we uncover the relation between the chiral phase and the emergence of DQPT. In concrete terms, only by taking some special angles can DQPT be induced. We confirm the above relation by computing the non-analytic points in Loschmidt echo return rate function. Furthermore, through the analysis of the corresponding dynamical partition function, we reveal the mechanism of the emergent DQPT and deduce the analytical expression of dynamical partition function's zero points' coordinates. Based on the analytic expression, one can obtain all the angles that induce DQPT's emergence and predict more possible DQPT in the system.

cond-mat.stat-mech↗

arXiv2024

The global phase diagram of the cluster-XY spin chain with dissipation

We study the ground-state phase diagram of a non-Hermitian cluster-XY spin chain in the language of free fermions. By calculating the second derivative of ground-state energy density and various types of order parameters, we establish the global ground-state phase diagram of the model, exhibiting rich quantum phases and corresponding phase transitions. Specially, the results reveal that the non-Hermitian cluster-XY model contains five different phases and two critical regions, i.e., ferromagnetic (FM), antiferromagnetic (AFM), symmetry-protected topological (SPT), paramagnetic (PM), Luttinger liquid-like phase, as well as critical region I and II. The order parameters and critical behaviors are investigated and the correctness of the theory is confirmed.

cond-mat.stat-mech↗

arXiv2024

Gifts from long-range interaction: Emergent gapless topological behaviors in quantum spin chain

Topology in condensed matter physics is typically associated with a bulk energy gap. However, recent research has shifted focus to topological phases without a bulk energy gap, exhibiting nontrivial gapless topological behaviors. In this letter, we explore a cluster Ising chain with long-range antiferromagnetic interactions that decay as a power law with the distance. Using complementary numerical and analytical techniques, we demonstrate that long-range interactions can unambiguously induce an algebraic topological phase and a topological Gaussian universality, both of which exhibit nontrivial gapless topological behaviors. Our study not only provides a platform to investigate the fundamental physics of quantum many-body systems but also offers a novel route toward searching for gapless topological phases in realistic quantum simulators.

cond-mat.str-el↗

arXiv2024

Quantum phase transition and critical behavior between the gapless topological phases

The phase transition between gapped topological phases represents a class of unconventional criticality beyond the Landau paradigm. However, recent research has shifted attention to topological phases without a bulk gap, where the phase transitions between them are still elusive. In this work, based on large-scale density matrix renormalization group techniques, we investigate the critical behaviors of the extended quantum XXZ model obtained by the Kennedy-Tasaki transformation. Using fidelity susceptibility as a diagnostic, we obtain a complete phase diagram, which includes both topological nontrivial and trivial gapless phases. Furthermore, as the XXZ-type anisotropy parameter $Δ$ varies, both the critical points $h_c$ and correlation length exponent $ν$ remain the same as in the $Δ=0$ case, characterized by $c=3/2$ (Ising + free boson) conformal field theory. Our results indicate that fidelity susceptibility can effectively detect and reveal a stable unconventional critical line between the topologically distinct gapless phases for general $Δ$. This work serves as a valuable reference for further research on phase transitions within the gapless topological phase of matter.

cond-mat.str-el↗

arXiv2024

Topological edge modes and phase transition in the critical fermionic chain with long-range interaction

The long-range interaction can fundamentally alter properties in gapped topological phases such as emergent massive edge modes. However, recent research has shifted attention to topological nontrivial critical points or phases, and it is natural to explore how long-range interaction influences them. In this work, we investigate the topological behavior and phase transition of extended Kitaev chains with long-range interactions, which can be derived from the critical Ising model via the Jordan-Wigner transformation in the short-range limit. Specifically, we analytically find the critical edge modes at the critical point remain stable against long-range interaction. More importantly, we observe these critical edge modes remain massless even when long-range interactions become substantially strong. As a byproduct, we numerically find that the critical behavior of the long-range model belongs to the free Majorana fermion universality class, which is entirely different from the long-range universality class in usual long-range spin models. Our work could shed new light on the interplay between long-range interactions (frustrated) and the gapless topological phases of matter.

cond-mat.str-el↗

arXiv2024

Quantum phase transition between topologically distinct quantum critical points

By constructing an exactly solvable spin model, we investigate the critical behaviors of transverse field Ising chains interpolated with cluster interactions, which exhibit various types of topologically distinct Ising critical points. Using fidelity susceptibility as an indicator, we establish the global phase diagram, including ferromagnetic, trivial paramagnetic, and symmetry-protected topological phases. Different types of critical points exist between these phases, encompassing both topologically trivial and non-trivial Ising critical points, as well as Gaussian critical points. Importantly, we demonstrate the existence of a Lifshitz transition between these topologically distinct Ising critical points, with central charge and critical exponents determined through finite-size scaling. This work serves as a valuable reference for further research on phase transitions within the gapless quantum phase of matter.

cond-mat.str-el↗

arXiv2024

Universal entanglement spectrum in gapless symmetry protected topological states

Quantum entanglement marks a definitive feature of topological states. However, the entanglement spectrum remains insufficiently explored for topological states without a bulk energy gap. Using a combination of field theory and numerical techniques, we accurately calculate and analyze the entanglement spectrum of gapless symmetry protected topological states in one dimension. We highlight that the universal entanglement spectrum not only encodes the nontrivial edge degeneracy, generalizing the Li-Haldane conjecture to gapless topological states, but also contains the operator content of the underlying boundary conformal field theory. This implies that the bulk wave function can act as a fingerprint of both quantum criticality and topology in gapless symmetry protected topological states. We also identify a symmetry enriched conformal boundary condition that goes beyond the conventional conformal boundary condition.

cond-mat.str-el↗

arXiv2024

Emergent entanglement phase transitions in non-Hermitian Aubry-André-Harper chains

We investigate the entanglement dynamics of the non-Hermitian Aubry-André-Harper (AAH) chain. The results reveal that by increasing quasiperiodic strength, a phase transition occurs from the area law induced by non-Hermitian skin effect to the area law arising from Anderson localization. For the former, the entanglement entropy follows a non-monotonic process, i.e., it increases first, then oscillates, and finally converges to a stable value. While for the latter, the entanglement entropy remains low because the wave function is not expandable in Anderson's localization region. The early-stage behavior of entanglement entropy indicates that the two area-law cases are of different phases. Interestingly, the volume-law behavior emerges at the critical point between these two area-law phases. Our study reveals that the area laws induced by the skin effect and the Anderson localization is two different phases, and that a volume law can emerge at the phase transition point. The understanding of the entanglement phase transition induced by disorder and skin effect is thus deepened.

cond-mat.dis-nn↗

arXiv2023

Critical quantum geometric tensors of parametrically-driven nonlinear resonators

Parametrically driven nonlinear resonators represent a building block for realizing fault-tolerant quantum computation and are useful for critical quantum sensing. From a fundamental viewpoint, the most intriguing feature of such a system is perhaps the critical phenomena, which can occur without interaction with any other quantum system. The non-analytic behaviors of its eigenspectrum have been substantially investigated, but those associated with the ground state wavefunction have largely remained unexplored. Using the quantum ground state geometric tensor as an indicator, we comprehensively establish a phase diagram involving the driving parameter $\varepsilon$ and phase $ϕ$. The results reveal that with the increase in $\varepsilon$, the system undergoes a quantum phase transition from the normal to the superradiant phase, with the critical point unaffected by $ϕ$. Furthermore, the critical exponent and scaling dimension are obtained by an exact numerical method, which is consistent with previous works. Our numerical results show that the phase transition falls within the universality class of the quantum Rabi model. This work reveals that the quantum metric and Berry curvature display diverging behaviors across the quantum phase transition.

quant-ph↗

arXiv2023

Dynamical phase transition and scaling in the chiral clock Potts chain

Based on time-dependent variational principle (TDVP) techniques, we investigate the dynamical critical behavior of quantum three-state Potts chains with chiral interactions. Using Loschmidt echo, order parameter, and entanglement entropy as an indicator, we show that as the chiral interaction $θ$ increases, the first critical time $t_{1}^{*}$ shift towards lower values, indicating a chirality-enhanced dynamical phase transition. Moreover, we perform dynamical scaling for the Loschmidt echo and obtain the critical exponent $ν$ at the non-conformal critical point. The results show that as the chiral interaction $θ$ increases, the correlation length exponent $ν$ decreases, which is similar to the long-range interaction case. Finally, we give a simple physical argument to understand the above numerical results. This work provides a useful reference for further research on many-body physics out of equilibrium with chiral interaction.

cond-mat.stat-mech↗

arXiv2023

Emergent self-duality in long range critical spin chain: from deconfined criticality to first order transition

Over the past few decades, tremendous efforts have been devoted to understanding self-duality at the quantum critical point, which enlarges the global symmetry and constrains the dynamics. In this letter, we employ large-scale density matrix renormalization group simulations to investigate the critical spin chain with long-range interaction $V(r) \sim 1/r^α$. Remarkably, we reveal that the long-range interaction drives the deconfined criticality towards a first-order phase transition as $α$ decreases. More strikingly, the emergent self-duality leads to an emergent symmetry and manifests at these first-order critical points. This discovery is reminiscent of self-duality protected multicritical points and provides the example of the critical line with generalized symmetry. Our work has far-reaching implications for ongoing experimental efforts in Rydberg atom quantum simulators.

cond-mat.str-el↗

arXiv2023

Non-Hermitian Stark Many-Body Localization

Utilizing exact diagonalization (ED) techniques, we investigate a one-dimensional, non-reciprocal, interacting hard-core boson model under a Stark potential with tail curvature. By employing the non-zero imaginary eigenenergies ratio, half-chain entanglement entropy, and eigenstate instability, we numerically confirm that the critical points of spectral real-complex (RC) transition and many-body localization (MBL) phase transition are not identical, and an examination of the phase diagrams reveals that the spectral RC transition arises before the MBL phase transition, which suggests the existence of a novel non-MBL-driven spectral RC transition. These findings are quite unexpected, and they are entirely different from observations in disorder-driven interacting non-Hermitian systems. This work provides a useful reference for further research on phase transitions in disorder-free interacting non-Hermitian systems.

cond-mat.quant-gas↗

arXiv2023

Anderson Localization and Swing Mobility Edge in Curved Spacetime

We construct a quasiperiodic lattice model in curved spacetime to explore the crossover concerning both condensed matter and curved spacetime physics. We study the related Anderson localization and find that the model has a clear boundary of localized-extended phase separation, which leads to a swing mobility edge, i.e., the coexistence of localized, swing and sub-extended phases. The swing mobility edge, first reported here, features the phase-dependent eigenstate, that is, the eigenstate swing between the extended and localized state for differnt phase parameter of the quasiperiodic potential. Furthermore, A novel self-consistent segmentation method is developed to calculate the analytical expression of the critical point of phase separation, and the rich phase diagram is obtained by calculating the fractal dimension and scaling index in multifractal analysis.

cond-mat.dis-nn↗

arXiv2023

Non-Hermitian strongly interacting Dirac fermions: a quantum Monte-Carlo study

Exotic quantum phases and phase transition in the strongly interacting Dirac systems has attracted tremendous interests. On the other hand, non-Hermitian physics, usually associated with dissipation arising from the coupling to environment, emerges as a frontier of modern physics in recent years. In this letter, we investigate the interplay between non-Hermitian physics and strong correlation in Dirac-fermion systems. We develop a sign-problem-free projector quantum Monte-Carlo (QMC) algorithm for the non-Hermitian interacting fermionic systems. Employing state-of-the-art projector QMC simulation, we decipher the ground-state phase diagram of the Honeycomb Hubbard model in the presence non-Hermitian asymmetric spin resolved hopping processes. Intriguingly, the antiferromagnetic ordering induced by Hubbard interaction is enhanced by the non-Hermitian asymmetric hopping. More remarkably, our study reveals that critical properties of the quantum phase transition between Dirac semi-metal and AF ordered phases are consistent with the XY universality class in Hermitian system, implying Hermiticity is emergent at the quantum critical point. The numerically-exact QMC approach utilized in this study is easily applied to other non-Hermitian interacting fermionic models, hence paving a new avenue to investigating quantum many-body physics in non-Hermitian systems.

cond-mat.str-el↗

arXiv2023

Quantum criticality of a $\mathbb{Z}_{3}$ symmetric spin chain with long-range interactions

Based on large-scale density matrix renormalization group techniques, we investigate the critical behaviors of quantum three-state Potts chains with long-range interactions. Using fidelity susceptibility as an indicator, we obtain a complete phase diagram of the system. The results show that as the long-range interaction power $α$ increases, the critical points $f_{c}^{*}$ shift towards lower values. In addition, the critical threshold $α_{c}(\approx 1.43$) of the long-range interaction power is obtained for the first time by a non-perturbative numerical method. This indicates that the critical behavior of the system can be naturally divided into two distinct universality classes, namely the long-range ($α\textless α_c$) and short-range ($α\textgreater α_c$) universality classes, qualitatively consistent with the classical $ϕ^{3}$ effective field theory. This work provides a useful reference for further research on phase transitions in quantum spin chains with long-range interaction.

cond-mat.str-el↗