arXiv subjects

Xin-You Lü

Publications and source records attributed to Xin-You Lü.

At least 19 recordsLinked to original sources

arXiv2026

Multicritical dissipative phase transitions manipulated by dipole--dipole interactions

Precise control of criticality in superradiant phase transitions is essential for quantum state engineering and the simulation of nonequilibrium phase transitions. Here, we investigate theoretically multicritical phenomena in a dissipative two-Rydberg-atom cavity--QED system. The intrinisic dipole--dipole interaction between the two Rydberg atoms restructures the energy-level landscape of the atomic subsystem, thereby significantly modifying the boundary of the continuous second-order superradiant phase transition, and shifting both the phase boundary and the multicritical point toward weaker atom--cavity strengths. For sufficiently strong dipole--dipole interactions, the continuous second-order phase transition and the multicritical point both disappear, leaving only a discontinuous first--order phase transition that enables the emergence of a superradiant phase even at arbitrarily weak atom--cavity coupling. This work is of fundamental interest for studying dissipative quantum phase transitions, with potential implications for quantum precision measurement and quantum sensing.

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arXiv2026

Tripartite Interactions Induced Strongly Correlated Quantum Emissions

Efficient generation of multiquanta emission is crucial for quantum information processing but remains challenging due to its typical reliance on higher-order quantum processes. Here, we theoretically demonstrate strongly correlated photon-phonon emission enabled by direct tripartite interaction. This interaction facilitates the formation of high-order multiquanta states without more intermediate state transitions, thereby avoiding the suppressed transition rates associated with multiple sequential processes and substantially improving resonant transitions. As a result, high-efficiency strongly correlated even-quanta emission (e.g., two photons and two phonons) can be achieved in the presences of dissipation. Beyond that, we show that introducing two-photon dissipation enables strongly correlated odd-quanta emission (e.g., two photons and one phonon) in the tripartite interaction system by parity-protected suppression of single-photon loss and reconstruction of higher-order multiquanta processes. Our work extends multiquanta emission into the tripartite coupling regime and holds promising potential for applications in hybrid quantum networks.

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arXiv2026

Disorder-Induced Exponential Scaling of Subradiant Decay Rates

Subradiance, a hallmark cooperative phenomenon in waveguide QED, is characterized by a universal power-law scaling of decay rates with system size and underpins many applications in quantum information storage. Here, we demonstrate that disorder drives a sharp transition in the typical subradiant decay rates from power-law to exponential scaling, a phenomenon we term the subradiant scaling transition (SST). Through rigorous finite-size scaling analysis, we establish the SST as a critical phenomenon, characterized by a diverging characteristic scale of the decay rates at the transition point $W_c=0$. Physically, the SST originates from Anderson localization, manifested by the physical equivalence between the characteristic scale and the localization length of the subradiant states. Our findings provide deep insights into the interplay between disorder and collective dynamics, unifying the underlying physical mechanisms of exponentially-scaled subradiant decay rates and Anderson localization in waveguide QED.

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arXiv2026

Towards High-Brightness Perfect Photon Blockade

Single-photon sources with high single-photon purity and high brightness are key elements of many future quantum technologies. While photon blockade (PB) is widely exploited in the development of such sources, achieving the coexistence of high purity and high brightness remains a long-standing challenge. Here, we identify a novel mechanism for high-brightness PB and demonstrate that near-ideal purity and near-ideal brightness can be simultaneously achieved in an extended nondegenerate two-photon Jaynes-Cummings model with two-body and three-body interactions. This mechanism is underpinned by a distinctive energy-level structure arising from the combined action of the two interactions. The energy levels in the multi-excitation manifold essentially retain a harmonic ladder of degenerate doublets, whereas in the single-excitation subspace the doublet degeneracy is lifted, with a finite splitting between the two levels. Consequently, when one bosonic mode is driven by a coherent continuous-wave pump, the former degeneracy enables the other bosonic mode to exhibit near-perfect PB even in the strong driving regime, while the latter splitting allows the mean photon number of that mode to approach unity. Our proposed scheme overcomes the outstanding challenge and offers a promising pathway toward realizing ideal single-photon sources.

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arXiv2026

Frequency-resolved N-photon correlations in the ultra-strong coupling regime

Frequency-resolved photon emission is central to applications from quantum information encoding to high-resolution spectroscopy, and then studying their correlations is therefore essential for revealing the underlying emission pathways and multiphoton statistics. Here, we investigate frequency-resolved N-photon correlations in an ultrastrongly coupled cavity QED system where a qubit interacts with a single-mode cavity. Owing to counter-rotating interactions, the eigenstates and energy spectrum are strongly modified, giving rise to rich spectral and statistical properties in the emitted frequency-resolved photons. Through frequency-selective detection, we reveal pronounced multiphoton antibunching, as well as multiphoton bunching originating from cascade transitions among dressed eigenstates. In particular, we show that parity symmetry plays a decisive role in shaping these correlations. The symmetry-breaking opens additional transition channels and dramatically enhances the generation of correlated photon pairs and even photon triplets of different frequencies. Our work extends frequency-resolved correlations to the ultra-strong coupling regime and demonstrates their potential as a sensitive probe of symmetry in light-matter interaction systems.

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arXiv2026

Decoherence-free Behaviors of Quantum Emitters in Dissipative Photonic Graphene

Achieving decoherence-free quantum state manipulation is a paramount goal in modern quantum technologies. To this end, we demonstrate its implementation in a two-dimensional dissipative photonic graphene featuring exceptional rings. Employing the resolvent method, we analytically explore the quantum dynamics of emitters coupled to photonic graphene. In the thermodynamic limit, our analysis predicts a dissipation-dependent logarithmic relaxation for a single quantum emitter, alongside a pronounced quantum Zeno effect that slows the decay with increased dissipation. Notably, within a finite lattice, the excitation of single quantum emitter stabilizes in a decoherence-protected quantum state, which is identified as a dissipation-robust quasilocalized state. Interestingly, this state, together with a dark state, facilitates decoherence-free interactions between quantum emitters. This capability can be extended to topological graphenic platforms, where edge states mediate analogous protected interactions among giant atoms. Our findings highlight a promising path toward protecting quantum coherence in practical, high-dimensional photonic environment through dissipation engineering.

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arXiv2026

Exceptional Point Superradiant Lasing with Ultranarrow Linewidth

Achieving superradiant lasing with an ultranarrow linewidth is crucial for enhancing atomic clock stability in quantum precision measurement. By employing the exceptional point (EP) property of the system, we demonstrate theoretically superradiant lasing with linewidths in the $μ$Hz range, sustained at the high-power level. This is achieved by incoherently pumping optical lattice clock transitions with ultracold alkaline-earth strontium-87 atoms in the EP of a $\mathcal{PT}$-symmetric system. Physically, the atomic coherence reaches a maximum in the EP, significantly amplifying the superradiance effect and resulting in superradiant lasing with an ultranarrow linewidth. This linewidth is even three orders of magnitude smaller than that of superradiant lasing in the systems without EP. Our work extends the realm of superradiant lasing by introducing the EP property, and offers promising applications for developing atomic clocks with exceptional stability and accuracy.

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arXiv2026

Exotic collective behaviors of giant quantum emitters in two-dimensional baths

Nonlocal light-matter interactions with giant atoms in high-dimensional environments are not only fundamentally intriguing for testing quantum electrodynamics beyond the dipole approximation but also crucial for building high-dimensional quantum networks and engineering multipartite entangled states. Given the enigmatic and largely uncharted collective signatures exhibited by multiple giant atoms within two-dimensional optical baths, we delve into their nonperturbative collective dynamics within the single-excitation subspace, focusing on the case where they are coupled to a common two-dimensional photonic reservoir and employing a resolvent operator approach. We demonstrate that precisely engineered atomic arrangements lead to unconventional quantum dynamics, featuring non-Markovianity-induced beats and long-lived bound states in the continuum, thereby providing a versatile platform for implementing two-dimensional quantum memory. Phenomenologically, we observe the emergence of exotic photon emission patterns in both two- and three-dimensional (3D) baths. The emission directions are shown to be precisely controllable on demand through exact phase engineering of the coupling parameters, enabling a highly efficient chiral light-matter interface. Moreover, our generalization to a 3D bath reveals that coherent dipole-dipole interactions can survive despite the coupling to a continuum of modes, a finding that challenges conventional wisdom regarding decoherence.

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arXiv2025

Bound state in the continuum and multiple atom state transfer applications in a waveguide QED setup

Bound states in the continuum (BICs) have been extensively exploited to enhance light--matter interactions in metamaterials, yet their emergence and utility in multi-atom waveguide platforms remain far less explored. Here we study atom--waveguide-dressed BICs in a one-dimensional coupled-resonator waveguide, where two spatially separated atomic arrays couple to distinct resonators with time-dependent strengths. We show that these BICs support a standing-wave photonic mode and enable the transfer of an arbitrary unknown quantum state between the two arrays with fidelities exceeding $99\%$. The protocol remains robust against both disorder and intrinsic dissipation. Our results establish BICs as long-lived resources for high-fidelity quantum information processing in waveguide-QED architectures.

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arXiv2025

Disorder-Induced Strongly Correlated Photons in Waveguide QED

Strongly correlated photons play a crucial role in modern quantum technologies. Here, we investigate the probability of generating strongly correlated photons in a chain of N qubits coupled to a one-dimensional (1D) waveguide. We found that disorder in the transition frequencies can induce photon antibunching, and especially nearly perfect photon blockade events in the transmission and reflection outputs. As a comparison, in ordered chains, strongly correlated photons cannot be generated in the transmission output, and only weakly antibunched photons are found in the reflection output. The occurrence of nearly perfect photon blockade events stems from the disorder-induced near completely destructive interference of photon scattering paths. Our work highlights the impact of disorder on photon correlation generation and suggests that disorder can enhance the potential for achieving strongly correlated photon.

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arXiv2025

Intermittent chaos in an optomechanical resonator

Chaos is a fundamental phenomenon in nonlinear dynamics, manifesting as irregular and unpredictable behavior across various physical systems. Among the diverse routes to chaos, intermittent chaos is a distinct transition pathway, characterized by the temporal or spatial alternation between periodic and chaotic motions. Here, we experimentally demonstrate, for the first time, optomechanically induced intermittent chaos in an optical whispering-gallery-mode microresonator. Specifically, the system evolves from stable periodic oscillation through an intermittent-chaos regime before fully developing into chaotic motion. As system parameters vary, the proportion of chaotic motion in the time-domain increases asymptotically until chaotic dynamics dominates entirely. Moreover, it is counterintuitive that, intermittent chaos can act as noise of a favorable intensity compared with purely periodic or fully chaotic states, and enhance rather than reduce system's responses in nonlinear ultrasonic detection. These findings not only deepen the comprehensive understanding of chaos formation but also broaden its potential applications in high-precision sensing and information processing.

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arXiv2025

Strongly tilted field induced fractional quantized-drift in non-interacting system

Fractional quantized response appears to be a distinctive characteristic in interacting topological systems. Here, we discover a novel phenomenon of tilt-induced fractional quantize drift in non-interacting system constructed by a time-modulated superlattice subjected to a external time-independent gradient potential. Depending on the tilt strength, Rabi oscillations between adjacent lowest enegy bands caused by Landau-Zener tunneling, can induce that the one-cycle-averaged drift displacement is fraction, which is relate to the ratio of the sum of Chern numbers of multiple bands to the number of energy bands involved in Landau Zener tunneling. As representative examples, we construct fractional (1/3, 1/2) quantize drift only via adjusting period of lattice. The numerical simulations allow us to consider a realistic setup amenable of an experimental realization. Our findings will expand the research implications of both fractional quantize response and topological materials.

cond-mat.quant-gas↗

arXiv2025

Cavity QED based on strongly localized modes: exponentially enhancing single-atom cooperativity

Large single-atom cooperativity in quantum systems is important for quantum information processing. Here, we propose to exponentially enhance the single-atom cooperativity parameter by exploiting the strongly localized effect of modes in cavity quantum electrodynamics (QED) systems. By increasing the wing width of a cavity with special geometry symmetry, the interference property allows us to exponentially improves the quality factor Q without altering the mode volume V for cavities supporting subwavelength light modes. This effectively overcomes the trade-off between Q and V in conventional subwavelength Fabry-Perot cavities. Consequently, we demonstrate the occurrence of ultra-long vacuum Rabi oscillations and the generation of strong photon blockade by enhancing the single-atom cooperativity parameter. This work offers a promising approach for advancing coherent manipulation and holds significant potential for applications in establishing longer-distance quantum communication networks, enhancing the precision and stability of quantum sensors, and improving the efficiency of quantum algorithms.

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arXiv2025

Chiral Interaction Induced Near-Perfect Photon Blockade

Based on the scattering matrix method, we theoretically demonstrate that the chiral interaction can induce the almost perfect photon blockade (PB) in the waveguide-cavity quantum electrodynamics (QED) system. The mechanism relies on the multi-photon paths interference within the waveguide, which is clearly shown by the analytic parameter regime for $g^{(2)}(0)\approx0$. When $N$ cavities are introduced into the system, there are $N$ optimal parameter points accordingly for the almost perfect PB, where the required lowest chirality decreases exponentially with increasing $N$, and these optimal points are robust against disorder in the system's frequencies. Under resonant driving and fixed chirality conditions, the output light depends solely on the parity of $N$ ($N\ge2$), with a coherent state emerging for even numbers of cavities and a single-photon state for odd numbers. Our work offers an alternative route for achieving almost perfect PB effects with high single-photon transmission by employing the chirality of system, with potential application in the on-chip single-photon source with integrability.

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arXiv2025

Topological Quantum Batteries

We propose an innovative design for quantum batteries (QBs) that involves coupling two-level systems to a topological photonic waveguide. Employing the resolvent method, we analytically explore the thermodynamic performance of QBs. First, we demonstrate that in the long-time limit, only bound states significantly contribute to the stored energy of QBs. We observe that near-perfect energy transfer can occur in the topologically nontrivial phase. Moreover, the maximum stored energy exhibits singular behavior at the phase boundaries, where the number of bound states undergoes a transition. Second, when a quantum charger and a quantum battery are coupled at the same sublattice within a unit cell, the ergotropy becomes immune to dissipation at that location, facilitated by a dark state and a topologically robust dressed bound state. Third, we show that as dissipation intensifies along with the emergence of the quantum Zeno effect, the charging power of QBs experiences a temporary boost. Our findings offer valuable guidance for improving quantum battery performance in realistic conditions through structured reservoir engineering.

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arXiv2025

Experimental observation of parity-symmetry-protected phenomena in the quantum Rabi model with a trapped ion

Symmetry is crucial for gaining insights into the fundamental properties of physical systems, bringing possibilities in studying exotic phenomena such as quantum phase transitions and ground state entanglement. Here, we experimentally simulate a highly controllable extended quantum Rabi model, capable of tuning into the ultra-strong or deep coupling regime, in a spin-motion-coupled trapped ion. We observe that the phonon driven by such a model with parity symmetry preserved (broken) would experience double (single) excitation in the ultra-strong coupling regime. Quantum phenomena such as strong ground state entanglement and quantum superposition in systems occur with parity symmetry, and these phenomena disappear following the symmetry breaking. We also find sensitive responses for the two-level system entropy and phonon Wigner function in the deep coupling regime, depending on the parameter across the symmetry transition point. This work offers the prospect of exploring symmetry-controlled quantum phenomena and their applications in high-precision quantum technologies.

quant-ph↗

arXiv2024

Genuine Multipartite Entanglement induced by a Thermal Acoustic Reservoir

Genuine multipartite entanglement (GME) is not only fundamental interesting for the study of quantum-to-classical transition, but also is essential for realizing universal quantum computing and quantum networks. Here we investigate the multipartite entanglement (ME) dynamics in a linear chain of N LC resonators interacting optomechanically with a common thermal acoustic reservoir. By presenting the exact analytical solutions of system evolution, we predict the periodic generation of non-Gaussian ME, including the discrete and continuous variables entanglement. Interestingly, the GME is obtained even though the system is in a heat bath. The mechanism relies on the special acoustic environment featuring frequency comb structure. More importantly, our proposed model also allows the periodic generation of entangled multipartite cat states (MCSs), i.e., a typical GHZ state, with high fidelity. This work fundamentally broadens the fields of ME, and have wide applications in implementing thermal-noise-resistant quantum information processing and many-body quantum simulation.

quant-ph↗

arXiv2024

Topological bosonic Bogoliubov excitations with sublattice symmetry

Here we investigate the internal sublattice symmetry, and thus the enriched topological classification of bosonic Bogoliubov excitations of thermodynamically stable free-boson systems with non-vanishing particle-number-nonconserving terms. Specifically, we show that such systems well described by the bosonic Bogoliubov-de Gennes Hamiltonian can be in general reduced to particle-number-conserving (single-particle) ones. Building upon this observation, the sublattice symmetry is uncovered with respect to an excitation energy, which is usually hidden in the bosonic Bogoliubov-de Gennes Hamiltonian. Thus, we obtain an additional topological class, i.e., class AIII, which enriches the framework for the topological threefold way of free-boson systems. Moreover, a construction is proposed to show a category of systems respecting such a symmetry. For illustration, we resort to a one-dimensional (1D) prototypical model to demonstrate the topological excitation characterized by a winding number or symplectic polarization. By introducing the correlation function, we present an approach to measure the topological invariant. In addition, the edge excitation together with its robustness to symmetry-preserving disorders is also discussed.

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