arXiv subjects

Chenrong Liu

Publications and source records attributed to Chenrong Liu.

12 recordsLinked to original sources

arXiv2026

Weak Fragmentation and Thermalization in a Dipole-Conserving Bose-Hubbard Chain

We study Hilbert-space fragmentation and thermalization in a one-dimensional dipole-conserving Bose-Hubbard chain. By analyzing the structure of the Hamiltonian matrix in the Fock basis, we show that the system exhibits weak Hilbert-space fragmentation. We further construct an exponentially large family of frozen product states and derive analytical upper and lower bounds on their number. Using exact diagonalization, we examine the consequences of weak fragmentation for eigenstate half-chain entanglement, density relaxation dynamics, and level statistics. All these quantities reveal a transition from a weak eigenstate thermalization regime to a nonergodic regime with increasing on-site interaction strength. These results show that weak Hilbert-space fragmentation \textit{does not} preclude quantum chaos or thermalization, and provides a minimal platform for studying the interplay of dipole conservation, weak fragmentation, and ergodicity breaking.

cond-mat.quant-gas↗

arXiv2025

Noise-Resilient Quantum Metrology with Quantum Computing

Quantum computing has made remarkable strides in recent years, as demonstrated by quantum supremacy experiments and the realization of high-fidelity, fault-tolerant gates. However, a major obstacle persists: practical real-world applications remain scarce, largely due to the inefficiency of loading classical data into quantum processors. Here, we propose an alternative strategy that shifts the focus from classical data encoding to directly processing quantum data. We target quantum metrology, a practical quantum technology whose precision is often constrained by realistic noise. We develop an experimentally feasible scheme in which a quantum computer optimizes information acquired from quantum metrology, thereby enhancing performance in noisy quantum metrology tasks and overcoming the classical-data-loading bottleneck. We demonstrate this approach through experimental implementation with nitrogen-vacancy centers in diamond and numerical simulations using models of distributed superconducting quantum processors. Our results show that this method improves the accuracy of sensing estimates and significantly boosts sensitivity, as quantified by the quantum Fisher information, thus offering a new pathway to harness near-term quantum computers for realistic quantum metrology.

quant-ph↗

arXiv2025

Beyond Conventional Pairing: Bosonic Quartic Superfluidity, Exotic XY Magnetism, and Phase Criticality

We report two unprecedented bosonic quartic superfluid (BQSF) phases in binary boson mixtures with synthetic pair-hopping (SPH) interaction realizable through Floquet engineering, transcending the conventional bosonic superfluidity paradigm via high-order correlations. Through extensive numerical simulations, we demonstrate: (i) The paired super-counter-fluid (PSCF) phase that exhibits bosonic 'four-particle' correlations, directly mirroring fermionic 4e superconductivity; (ii) The symbiotic super-counter-fluid which is an anomalous quantum phase featuring intrinsically intertwined, non-zero PSCF and super-counter-fluid orders. Both phases further reveal unreported pseudo-spin-ordered XY ferromagnetic states with filling-dependent magnetization textures. Adjacent to BQSF phases, we uncover both a previously unreported quantum quadruple critical point induced by interexchange asymmetry and SPH-driven state-dependent criticality-the latter exhibiting distinct behavior from conventional two-component bosonic systems. We propose momentum-resolved noise correlation spectroscopy-building on established quantum gas microscopy techniques-as a direct probe for the characteristic signatures of these BQSF states. Our results establish a new paradigm in quantum matter, opening unprecedented avenues to explore (i) quartic quantum coherence, (ii) emergent collective phenomena, and (iii) extended XY magnetism-resolving a longstanding classification challenge while discove

cond-mat.quant-gas↗

arXiv2024

Ground-state phase diagram of two-component interacting bosons on a two-leg ladder

Using the cluster Gutzwiller mean-field method, we numerically study the ground-state phase diagram of the non-hard-core two-component interacting bosons trapped in a two-leg ladder with and without an artificial magnetic field. There are three quantum phases namely Mott insulator (MI), supercounterfluid (SCF), and superfluid (SF) are found in the phase diagram. Interestingly, several loophole SCF phases are observed at a sufficiently small intra- to inter-leg hopping ratio when the magnetic flux is absent. While if the ratio is not so small, the loophole SCF phase would disappear, but it can still be induced by applying a sufficiently large magnetic flux. Additionally, we also find that the presence of the magnetic flux leads to an enlargement of the MI lobe and the conventional SCF lobe. Moreover, the SF-MI phase boundary is quantitatively consistent with the strong-couping expansion at a weak hopping amplitude.

cond-mat.quant-gas↗

arXiv2023

Ground state properties of a multi-component bosonic mixture: a Gutzwiller mean-field study

Using the single-site Gutzwiller method, we theoretically study the ground state and the interspecies entanglement properties of interexchange symmetric multi-component (two- and three-) bosonic mixtures in an optical lattice, and the results are generalized to an $n$-component ($n=2,3,4,\cdots$) system. We compute the mean-field phase diagram, the interspecies entanglement entropy, and the ground state spectral decomposition. Three phases namely the $n$-component Superfluid state (nSF), the $n$-component Mott insulator state (nMI), and the Super-counter-fluid state (SCF) are observed. Interestingly, we find that there are $n-1$ SCF lobes to separate every two neighboring nMI lobes in the phase diagram. More importantly, we derive the exact general expression of the interspecies entanglement entropy for the SCF phase. In addition, we also investigate the demixing effect of an n-component mixture and demonstrate that the mixing-demixing critical point is independent of n.

cond-mat.quant-gas↗

arXiv2022

Generalized effective-potential Landau theory for a tunable state-dependent hexagonal optical lattice

We analytically study the ground-state phase diagrams of ultracold bosons with various values of the effective magnetic quantum number $m$ in a state-dependent hexagonal optical lattice by using the generalized effective-potential Landau theory, where the site-offset energy between the two triangular sublattice A and B is tunable. Our analytical calculations of third-order corrections are in reasonably good agreement with the previous cluster Gutzwiller calculations. Furthermore, we reveal the reason why the regions of the Mott lobes $(n,n)$ in phase diagrams for $m=0.02$ are unexpectedly expanded with increasing $J/U$ in deep lattice.

cond-mat.quant-gas↗

arXiv2022

Phase diagram of the two-component bosonic system with pair hopping in synthetic dimension

We systematically study the ground-state phase diagrams and the demixing effect of a two-dimensional two-component bosonic system with pair hopping in synthetic dimension by using the cluster Gutzwiller mean-field method. Our results show that when the interexchange symmetry between the two species is broken, the regions of the super-counter-fluidity state in the phase diagram are dramatically shrunk whenever the on-site pair hopping term is turned on or off. Unexpectedly, the non-integer Mott phase and the molecular superfluid phase predicted in our previous work \citetext{Z. Lin et al., \textcolor{blue}{Phys. Rev. Lett. \textbf{125}, 245301 (2020)}}, can only exist in such a system that the pair hopping term is opened, and more importantly, its interexchange symmetry must be broken. Moreover, the demixing effect of the two-component bosonic system with synthetic pair hopping interaction has also been studied, and we find that an incompletely demixed state is formed in the system when the strength of the interspecies on-site repulsive interaction is sufficiently large.

physics.atm-clus↗

arXiv2021

Enhancement of boson superfluidity in a one-dimensional Bose-Fermi mixture

We examine the effect of boson-fermion interaction in a one-dimensional Bose-Fermi mixture by using the density matrix renormalization group method. We show that the boson superfluidity is enhanced by fermions for a weak boson-fermion coupling at an approximate integer boson filling factor (e.g., $0.935\le ρ_b \le 1.0$), and this enhancement is produced both in a fermion metallic state and in a fermion insulating state. A metal-insulator phase transition of fermions induced by boson-fermion interaction is observed even though there is no fermion-fermion interaction in the parent Hamiltonian. Furthermore, we find that the boson superfluid order and density wave order can coexist in a deep fermion Mott region. All these features could be measured in future experiments and open up the possibility of detecting the new physical effect in the Bose-Fermi mixture.

cond-mat.quant-gas↗

arXiv2020

Novel quantum phases of two-component bosons with pair hopping in synthetic dimension

We study two-component (or pseudospin-1/2) bosons with pair hopping interactions in synthetic dimension, for which a feasible experimental scheme on a square optical lattice is also presented. Previous studies have shown that two-component bosons with on-site interspecies interaction can only generate nontrivial interspecies paired superfluid (super-counter-fluidity or pair-superfluid) state. In contrast, apart from interspecies paired superfluid, we reveal two new phases by considering this additional pair hopping interaction. These novel phases are intraspecies paired superfluid (molecular superfluid) and an exotic non-integer Mott insulator which shows a non-integer atom number at each site for each species, but an integer for total atom number.

cond-mat.quant-gas↗

arXiv2019

Temperature-dependent spectral function of a Kondo impurity in an $s$-wave superconductor

Using the numerical renormalization group method, the effect due to a Kondo impurity in an $s$-wave superconductor is examined at finite temperature ($T$). The $T$-behaviors of the spectral function and the magnetic moment at the impurity site are calculated. At $T$=0, the spin due to the impurity is in singlet state when the ratio between the Kondo temperature $T_k$ and the superconducting gap $Δ$ is larger than 0.26. Otherwise, the spin of the impurity is in a doublet state. We show that the separation of the double Yu-Shiba-Rusinov peaks in the spectral function shrinks as $T$ increases if $T_k/Δ<0.26$ while it is expanding if $T_k/Δ>0.26$ and $Δ$ remains to be a constant. These features could be measured by experiments and thus provide a unique way to determine whether the spin of the single Kondo impurity is in singlet or doublet state at zero temperature.

cond-mat.str-el↗

arXiv2019

Sweeping cluster algorithm for quantum spin systems with strong geometric restrictions

Quantum spin systems with strong geometric restrictions give rise to rich quantum phases such as valence bond solids and spin liquid states. However, the geometric restrictions often hamper the application of sophisticated numerical approaches. Based on the stochastic series expansion method, we develop an efficient and exact quantum Monte Carlo "sweeping cluster" algorithm which automatically satisfies the geometrical restrictions. Here we use the quantum dimer model as a benchmark to demonstrate the reliability and power of this algorithm. Comparing to existing numerical methods, we can obtain higher accuracy results for a wider parameter region and much more substantial system sizes.

cond-mat.stat-mech↗

arXiv2017

Bosonic Integer Quantum Hall States without Landau Levels on Square Lattice

We study an interacting two-component hard-core bosons on square lattice for which, in the presence of staggered magnetic flux, the ground state is a bosonic integer quantum Hall (BIQH) state. Using a coupled-wire bosonization approach, we analytically show this model exhibits a BIQH state at total charge half filling associated with a symmetry-protected topological phase under $U(1)$ charge conservation. These theoretical expectations are verified, using the infinite density matrix renormalization group method, by providing numerical evidences for: (i) a quantized Hall conductance $σ_{xy}=\pm2$, and (ii) two counter-propagating gapless edge modes. Our model is a bosonic cousin of the fermionic Haldane model and serves as an additional case of analogy between bosonic and fermionic quantum Hall states.

cond-mat.quant-gas↗