arXiv subjects

H. Z. Shen

Publications and source records attributed to H. Z. Shen.

At least 19 recordsLinked to original sources

arXiv2026

Giant-Atom-Induced High-Order Output Zeros in a Coupled-Cavity Array

Coherent perfect absorption, zero transmission and zero reflection are several scattering phenomena governed by interference engineering in Hermitian and non-Hermitian systems. Higher-order coherent perfect absorption can significantly broaden the absorption bandwidth, while existing implementations rely on scattering zero degeneracy induced by exceptional points or additional momentum-dependent phase delays introduced in incident waves. We propose a scheme where a giant atom couples to a one-dimensional coupled-cavity array at two spatially separated sites. The spatially separated coupling configuration of the giant atom generates tunable nonlocal interference phases that dominate the scattering interference process. We further investigate the zero-reflection and zero-transmission behaviors under single-sided incidence. Remarkably, we find that for certain parameter choices, zero transmission can persist over the entire propagating band, rather than being restricted to a single momentum. Our results reveal that the giant-atom interference mechanism enables bandwidth-enhanced coherent perfect absorption and bandwidth-enhanced zero transmission in the absence of exceptional points and incident momentum-dependent phase delays. Our work provides a physical route for coherent wave manipulation in coupled-cavity quantum networks.

quant-ph↗

arXiv2026

Quantum Battery Enhancement via Degenerate Optical Parametric Amplifier and Common Reservoirs

We investigate a nonreciprocal quantum battery in which the charger and battery share one or two common reservoirs, with the charger driven by a degenerate optical parametric amplifier (DOPA). Reservoir-mediated dissipative interactions enable directional energy transfer, while the DOPA provides additional parametric am plification. We show that, in the stable below-threshold regime, the DOPA can enhance the battery energy and average charging power, with the nonlinear gain and pump phase providing effective control of the charging dynamics. Further optimization of the dissipative-coupling asymmetry improves the stored energy. These fea tures persist for both single- and two-common-reservoir configurations, demonstrating a tunable strategy for enhancing open-system quantum-battery charging.

physics.optics↗

arXiv2026

Giant-atom-mediated photon blockade

Photon blockade is a phenomenon where the presence of system nonlinearity causes the output to consist of single photons, which has been extensively studied in point atom systems, but it is barely explored in giant atom ones. In this paper, we propose giant atom-mediated photon blockade scheme based on two cavities and three cavities systems with driving field applied to the first cavity. We show that simultaneous unconventional photon blockades (UPBs) can not occur in the point atom system (the atom coupling only to the leftmost cavity) due to there always existing a cavity to have a single path. In contrast, the spatially extended nature of giant atom enables coupling to multiple cavities and allows for the introduction of a phase and coupling strength. Consequently, simultaneous UPBs in multiple cavities can be obtained due to the multipath destructive interference. Moreover, by manipulating the detuning, we observe simultaneous conventional photon blockades (CPBs) in multiple cavities. Finally, we study simultaneous two-photon blockades (2PBs) in point atom multiple cavities system.

quant-ph↗

arXiv2026

Bound-State Engineered Quantum Batteries Against Decoherence

Quantum batteries promise revolutionary advantages for energy storage but are fundamentally crippled by environmental decoherence, which induces self-discharge and rapid "aging." Here, we crack this critical bottleneck by exploiting the decoherence-suppression mechanism: the formation of system-environment bound states. We consider a charger-battery system embedded in a three-dimensional anisotropic photonic crystal bath and derive exact non-Markovian dynamics. Strikingly, we reveal a tunable phase diagram where modulating the atomic eigenfrequency and coupling strength switches the system between zero, one, and two bound states. In the presence of two bound states, the battery energy evolves into a persistent periodic oscillation, enabling lossless energy storage and on-demand extraction indefinitely, effectively realizing an aging-free quantum battery. Conversely, the absence of bound states leads to complete energy decay. We also demonstrate that even during self-discharge, a single bound state can stabilize extractable energy. This work establishes bound-state formation as a powerful and feasible strategy for combating decoherence, offering a clear blueprint for designing durable solid-state quantum batteries in non-Markovian photonic platforms.

physics.optics↗

arXiv2026

Preparation of Multimode NOON States via Floquet-Engineered Conditional Chiral Excitation

The NOON states possess Heisenberg-limited phase sensitivity and are crucial for quantum-enhanced metrology. In our work, we develop a Floquet-engineered conditional-routing framework in which a $d$-level quantum controller mediates the dynamics of $d$ bosonic modes. For an arbitrary odd dimension $d=2s+1$, the $d$-level system can act as a ``quantum knob" by tuning its initial states to coherently control the direction of chiral excitation flow, such that different controller eigenstates generate distinct cyclic-routing branches of the bosonic excitations. By choosing $s$ harmonics, we construct an exact qudit-controlled cyclic permutation and use it to formulate a general protocol for preparing odd-$d$-mode NOON states. The same framework also enables programmable complex amplitudes through appropriate preparation of the controller state. As concrete realizations, we show that the three-mode case requires only a single harmonic and exhibits two oppositely directed chiral branches together with a stationary branch, whereas the five-mode case requires two harmonics and both nearest- and next-nearest-neighbor chiral hoppings. Meanwhile, taking the three-mode realization as a representative example, we assess the influence of systematic imperfections and dissipation on the conditional-routing dynamics and identify parameter regimes in which the routing operation remains accurate. Our results establish a systematic Floquet construction for controllable chiral routing and multimode NOON-state generation in arbitrary odd-dimensional networks, with potential applications in quantum information processing and quantum metrology.

quant-ph↗

arXiv2026

Amplification of Weak Forces via Parametric Interactions and Non-Markovian Effects in Cavity Optomechanics

Weak force amplification describes the process of amplifying a faint low-frequency signal by means of an additional high-frequency modulation, which plays a vital role in quantum sensing and high-precision measurement. However, the potential enhancement of weak-force amplification in non-Markovian environments has received little attention. In this paper, we firstly study the amplification of weak forces within cavity-optomechanical systems incorporating a degenerate optical parametric amplifier (DOPA) under the Markovian assumption. The results show that the weak force can be effectively amplified by using two high-frequency signals via vibrational resonance through adjusting the strength and phase of the DOPA with different pumping frequencies. Moreover, we extend the study of the amplification of the weak force to the non-Markovian environment which consists of a collection of infinite oscillators. We illustrate that the amplification exhibits a conversion from the non-Markovian regime to Markovian regime by controlling environmental spectral width. This conversion leads to enhancements of amplification, which originates from the excitation backflow obtained through the interaction between the cavity and non-Markovian environment. By controlling DOPA to amplify weak forces, the study achieves amplification in the non-Markovian regime, offering new directions for quantum optics research.

physics.optics↗

arXiv2026

Higher-Order Exceptional Points Induced by Non-Markovian Environments

Exceptional points (EPs) are central to non-Hermitian physics because of their unique properties and broad application prospects. While extensively studied in parity-time ($\mathcal{P}\mathcal{T}$)-symmetric systems and under Markovian dynamics, their exploration in broader pseudo-Hermitian settings, particularly in those involving non-Markovian environments, remains largely unexplored. In this study, we investigate a pseudo-Hermitian system consisting of three coupled optical cavities interacting with non-Markovian environments. Compared to the Markovian baseline, we demonstrate that the emergence of non-Markovian memory effects enlarges the dimensionality of the parameter space of the system, thereby giving rise to higher-order EPs. Furthermore, we show that these non-Markovianity-induced higher-order EPs admit a topological characterization as defects in the relevant pseudo-Hermitian parameter space, with quantized charges described by resultant winding numbers. Moreover, we observe that the pseudo-Hermitian system with an effective gain induced by coherent perfect absorption enables the higher-order EPs to be directly read out from the output spectrum. We also note that the non-Markovian mechanism for generating higher-order EPs is not restricted to pseudo-Hermitian systems, but can be extended to generic non-Hermitian quantum systems. Additionally, possible experimental implementations based on superconducting circuits are also discussed.

physics.optics↗

arXiv2026

Anomalous mobility edges and extended-localized transition in a quasiperiodic emitter-cavity array

The manipulation of localization in quasiperiodic systems by mobility edges or localization transition holds significant physical importance. In this letter, we demonstrated that the dissipation can induce the emergence of anomalous mobility edges and extended-localized transition in emitter-cavity arrays controlled by quasiperiodic potentials. Specifically, we observe that the localization properties of emitters is governed by the nature of quantum bound states, either discrete or embedded in continuum, providing a unified mechanism linking the emitter-photon bound physics to quasiperiodic criticality. Depending on the bound state discrete or continuumlike, the induced effective excitation hopping exhibits either exponentially decaying or sinusoidally oscillating, giving rise to the formation of localized or critical states, respectively. Through a generalized duality transformation, we analytically determine the anomalous mobility edges and the critical strength of potential, enabling the construction of a full phase diagram. The study reveals that the physical characteristics of cavity exert a significant influence on excitation localization. Therefore, the manipulation of excitation localization can be achieved solely by adjusting the cavity fields.

quant-ph↗

arXiv2026

Coupling Enhancement and Symmetrization in Dissipative Optomechanical Systems

Observing few-photon optomechanical effects remains a significant challenge in optomechanical systems. To investigate intrinsic radiation-pressure-induced nonlinear effects in the few-photon regime, it is essential to strengthen the interaction between few photons and a finite number of phonons. In this work, we enhance the radiation-pressure nonlinearity by introducing a two-laser coherent driving scheme together with an enhanced cross-Kerr nonlinearity, resulting in a setup that can be effectively described within a circuit QED platform. By properly tuning the two driving laser fields and the cross-Kerr interaction so that the effective optomechanical coupling becomes real, we theoretically establish a symmetric optomechanical model in which the photon and phonon modes exhibit analogous fluctuation dynamics. Within this framework, we analyze the optimal reciprocal transport of the input laser field and identify the critical boundary associated with the onset of different coupling regimes. We also compare the optical signal scattering behavior in both dissipative equilibrium and nonequilibrium symmetric optomechanical systems, with and without non-rotating-wave contributions. Our work provides a controllable route to enhance optomechanical coupling, extending into the ultrastrong-coupling regime, and opens opportunities for exploring few-photon optomechanical effects.

quant-ph↗

arXiv2025

Frequency conversion between optical and microwave photons in non-Markovian environments

In this paper, we propose a scheme for frequency conversion between optical photons and microwave photons in non-Markovian environments using both magnetic and mechanical excitations as intermediate media. When the frequencies of optical photons, magnons, phonons, and microwave photons resonance, the conversion efficiency can be made close to reach 98.76$\%$ by adjusting the defined complex cooperativities, while in the case of Markovian, the conversion efficiency is 90.44$\%$. By controlling the environmental spectral widths, the efficiency of frequency conversion exhibits a transition from Markovian regimes to non-Markovian regimes. This transformation simultaneously improves frequency conversion efficiency and conversion bandwidth, which is due to the excitation backflow generated by the interaction between the system and the non-Markovian environments. In the case, when the optical pump power in the non-Markovian regimes are of a large order of magnitude, the conversion bandwidth can be increased, but at the cost of reduced conversion efficiency. Our scheme improves the frequency conversion efficiency and bandwidth between optical photons and microwave photons, breaking the limitations of frequency conversion in Markovian environments and providing a new approach for long-distance quantum communication research of other non-Markovian quantum systems in quantum optics.

physics.optics↗

arXiv2025

Simultaneous nonreciprocal unconventional photon blockade via two degenerate optical parametric amplifiers in spinning resonators

We propose a scheme to achieving simultaneous nonreciprocal unconventional photon blockade in a system of two coupled spining resonators marked by modes a and b, each incorporating an degenerate optical parametric amplifier (DOPA). By rotating the resonators, input light from opposite directions induces opposite Sagnac-Fizeau shifts. These shifts result in the emergence or absence of quantum destructive interference in two-photon excitation processes. Specifically, when destructive quantum interference occurs, photons from one input direction are simultaneously blocked in both resonators, whereas the absence of complete destructive quantum interference causes the blockade effect to vanish for inputs from the opposite direction. We analytically give the optimal parameter conditions to achieve simultaneous strong photon blockade with the parametric amplification. By adjusting the Sagnac-Fizeau shifts, we can make mode a nonreciprocal photon blockade, while mode b exhibits photon blockade in both directions. This work lays a theoretical foundation for the development of multimode simultaneous nonreciprocal unconventional single-photon devices, which hold promising potential in multichannel topological optics and chiral quantum technologies.

physics.optics↗

arXiv2025

Non-Markovian dynamics with a driven three-level giant atom in a semi-infinite photonic waveguide

The non-Markovian effects of open quantum systems subjected to external environments are deemed to be valuable resources in quantum optics and quantum information processing. In this work, we investigate the non-Markovian dynamics of a three-level giant atom coupling with a semi-infinite photonic waveguide through multiple coupling points and driven by a classical driving field. We derive the analytical expressions for the probability amplitudes of the driven three-level giant atom and obtain two independent conditions. We find two different types of bound states (including the static bound states and the periodic equal-amplitude oscillating bound states) and discuss the physical origins of the bound states formation. Moreover, we discuss the case of the driven three-level giant atom interacting with the infinite photonic waveguide, where there is only one purely imaginary solution (i.e., only one bound state condition exists) for its complex frequency (coming from the absence of mirror at one end of the waveguide) compared to that of a driven three-level giant atom coupling with a semi-infinite photonic waveguide. With this, we also find two different types of bound states, including the static bound state and the periodic equal-amplitude oscillating bound states. Finally, the above results are generalized to a more general model involving a semi-infinite photonic waveguide coupling with an arbitrary number of noninteracting three-level giant atoms driven by the driving fields. The proposed protocol could provide a pathway to precisely elucidate the non-Markovian dynamics of driven, multi-level giant atoms coupled to semi-infinite or infinite photonic waveguides.

physics.optics↗

arXiv2025

Dressed bound states and non-Markovian dynamics with a whispering-gallery-mode microcavity coupled to a two-level atom and a semi-infinite photonic waveguide

We investigate the dressed bound states (DBS) in an open cavity with a whispering-gallery-mode microring coupled to a two-level atom and a waveguide with a mirror at the right end. We demonstrate that the non-Hermiticity of an open cavity facilitates the formation of the DBS, which consists of the vacancy-like DBS and Friedrich-Wintgen DBS. By deriving analytical conditions for these DBS, we show that when a two-level atom couples to the standing-wave mode that corresponds to a node of the photonic wave function the vacancy-like DBS occur, which are characterized by null spectral density at cavity resonance. Conversely, Friedrich-Wintgen DBS can be realized by continuously adjusting system parameters and indicated by the disappearance of the Rabi peak in the emission spectrum, which is a distinctive feature in the strong-coupling regime. Moreover, we extend our analysis to the non-Markovian regime and find that our results are consistent with those obtained under the Markovian approximation in the wideband limit. In the non-Markovian regime, we analyze DBS for both zero and non-zero accumulated phase factors. For zero accumulated phase factors, the non-Markovian regime exhibits higher peak values and longer relaxation times for vacancy-like DBS compared to the Markovian regime, where the Friedrich-Wintgen DBS are absent in the non-Markovian case. Finally, we establish the correspondence between the energy spectrum and bound state conditions for non-zero accumulated phase factors and analyze the influence of various parameters on non-Markovian bound states. Our work exhibits bound state manipulations through non-Markovian open quantum system, which holds great potential for building high-performance quantum devices for applications such as sensing, photon storage, and nonclassical light generation.

physics.optics↗

arXiv2025

Nonreciprocity and unidirectional invisibility in three optical modes with non-Markovian effects

In this work, we construct three coupled optical modes systems to obtain effective Hamiltonian mediated by coherent dissipative coupling during adiabatic elimination of large dissipation mode. We investigate the cooperative effect of coherent and dissipative photon-photon couplings in an open cavity system, which leads to nonreciprocity with a considerably large isolation ratio and flexible controllability. We discover unidirectional invisibility for electromagnetic wave propagation, which appears at the zero-damping condition (ZDC) for hybrid photon-photon modes and obtain transmission spectrum on the ZDC. We study the influences of the parameters on the nonreciprocal transmission of the system to capture the generic physics of the interference between coherent and dissipative couplings, which accurately reproduces the results of numerical simulation over a broad range of parameters. Moreover, we extend the study of nonreciprocal transmission with the Markovian approximation to the non-Markovian environments, which consist of a collection of oscillators (bosonic photonic modes) and give the adiabatic elimination method with non-Markovian effects. We illustrate that nonreciprocal transmission on ZDC exhibits a crossover from the non-Markovian to the Markovian regimes by controlling the environmental spectral width. This indicates a promising way to enhance or steer quantum nonreciprocal devices in optical cavities and provides potential applications for precision measurements and optical communications with non-Markovian effects.

physics.optics↗

arXiv2025

Emergent Non-Markovian Gain in Open Quantum Systems

Non-Markovian dynamics go beyond the Markovian approximation by capturing memory effects and information backflow in open quantum systems, which are crucial for describing realistic physical processes. In this work, we study the exact non-Markovian dynamics of a driven cavity coupled to an anisotropic three-dimensional photonic-crystal environment via counterrotating-wave interactions. We derive an exact analytical expression for the cavity amplitude satisfying the integro-differential equation, which includes the contributions of the bound states outside the continuum and the dissipative parts with the continuum spectrum. Based on the characteristic function method, we derive the exact non-Markovian master equation for the cavity, which contributes to the gain of the cavity. We give the physical origin of non-Markovian gain in the presence of bound states in the system consisting of cavity and environment, which has no Markovian counterparts due to the nonexponential gain in the non-Markovian structured environment. We find that three different types of bound states can be formed in the system, containing one bound state with no inversion of photon number, two bound states with the periodic equal-amplitude oscillation, and the gain with two complex roots without the bound states formation. We derive a current equation including the source from the driving field, the transient current induced by the change in the number of photons, and the two-photon current caused by the counterrotating-wave term. The results are compared with those given by the rotating-wave interactions and extended to a more general quantum network involving an arbitrary number of coupled cavities. Our findings may pave the way for a deeper understanding of non-Markovian dynamics with gain in quantum networks involving counterrotating-wave effects.

physics.optics↗

arXiv2025

Nonreciprocal quantum router with non-Markovian environments

Quantum routers are essential elements of quantum networks, enabling coherent information transfer between distant nodes. While their behavior has been extensively studied under Markovian approximations, investigations in non-Markovian regimes remain limited. In this paper, we study a nonreciprocal quantum router embedded in non-Markovian environments, enabling directional control of single photons, which allows transmission from one side while blocking it from the other. The cascade system under study consists of two quantum nodes: one comprising two coupled coplanar-waveguide resonators and the other featuring a superconducting ring resonator. Each node is respectively coupled to a single Yttrium iron garnet (YIG) disk, with nonreciprocity arising from the selective coupling between magnons and microwave photons in our model. We analytically derive the transmission and reflection spectra of the system when a photon is input respectively from the left and right sides of the transmission line in the non-Markovian regimes. Our results demonstrate that, with appropriate parameters, a single photon can be routed from a given input port to either of the two output ports, while being fully absorbed when incident from the opposite side. We further compare the scattering behavior in non-Markovian and Markovian regimes through numerical simulations. In the non-Markovian case, the transmission spectrum exhibits two unity peaks (two valleys with a minimum value of zero), whereas in the Markovian case, high transmission appears only within a narrow window near zero detuning when the photon is injected from the left. As the environmental bandwidth increases, non-Markovian results converge to the Markovian limit. This formalism may enable new applications in quantum information and communication exploiting non-Markovianity.

physics.optics↗

arXiv2024

Photon blockade in non-Hermitian optomechanical systems with nonreciprocal couplings

We study the photon blockade at exceptional points for a non-Hermitian optomechanical system coupled to the driven whispering-gallery-mode microresonator with two nanoparticles under the weak optomechanical coupling approximation, where exceptional points emerge periodically by controlling the relative angle of the nanoparticles. We find that conventional photon blockade occurs at exceptional points for the eigenenergy resonance of the single-excitation subspace driven by a laser field, and discuss the physical origin of conventional photon blockade. Under the weak driving condition, we analyze the influences of the different parameters on conventional photon blockade. We investigate conventional photon blockade at non-exceptional points, which exists at two optimal detunings due to the eigenstates in the single-excitation subspace splitting from one (coalescence) at exceptional points to two at non-exceptional points. \textbf{Unconventional photon blockade can occur at non-exceptional points, while it does not exist at exceptional points since the destructive quantum interference cannot occur due to the two different quantum pathways to the two-photon state being not formed.} The realization of photon blockade in our proposal provides a viable and flexible way for the preparation of single-photon sources in the non-Hermitian optomechanical system.

quant-ph↗

arXiv2024

Multiple single-photon generations in three-level atoms coupled to cavity with non-Markovian effects

In this paper, we show how to generate the multiple single-photon wavepackets of arbitrary temporal shape from an optical cavity coupled with $N$ three-level atoms driven by a driving field in the non-Markovian regime. We derive an exact analytical expression of the optimal driving field for generating such wavepackets, which depends on two detunings of the cavity and driving field with respect to the three-level atoms. The cavity we used consists of two mirrors facing each other, where one is perfect and the other exists the dissipation (one-sided cavity), which couples with the corresponding non-Markovian input-output fields. If the first single-photon wavepacket generated by the Markovian system is the same as the non-Markovian case, the Markovian system cannot generate the same multiple single-photon wavepackets as the non-Markovian one when the spectral widths of the other environments taking values different from the spectral width of the first environment, while setting the equal spectral widths for the different environments can generate this. The generated multiple different single-photon wavepackets are not independent of each other, which satisfy certain relations with non-Markovian spectral parameters. We analyse the transition from Markovian to non-Markovian regimes and compare the differences between them, where the cavity interacts simultaneously with the multiple non-Markovian environments. Finally, we extend the above results to a general non-Markovian quantum network involving many cavities coupled with driven three-level atoms.

quant-ph↗