arXiv subjects

Yu-Meng Ren

Publications and source records attributed to Yu-Meng Ren.

7 recordsLinked to original sources

arXiv2026

Nonreciprocal quantum rotation sensing via virtual-excitation enhancement in a spinning cavity

Quantum sensing with high precision and sensitivity plays an important role in quantum technologies and quantum information processing. Here, we propose a nonreciprocal quantum metrological scheme for estimating rotational angular velocity in a hybrid light-matter platform, where the setup consists of a spinning ring cavity coupled to a two-level system and an auxiliary bosonic mode. Through the Sagnac effect, the angular velocity is converted into a direction-dependent detuning, which modifies the effective light-matter dressing of the hybrid system. As a result, the angular velocity is encoded not only into the renormalized hybrid-mode spectrum, but also into the virtual excitations generated by ultrastrong coupling. These virtual excitations modify the polaritonic frequency response to rotation and enhance the quantum Fisher information (QFI) associated with angular velocity estimation, without requiring direct extraction of virtual excitations. Moreover, since the Sagnac-Fizeau shift enters the virtual-transition energy denominators, the metrological response becomes intrinsically different for opposite driving directions, leading to a tunable nonreciprocal sensitivity contrast. In addition, we also discuss a readout scheme and show that bundle emission coincidence counting can serve as an auxiliary direction-dependent readout channel. Our results provide a route toward exploiting nonreciprocal light-matter dressing and virtual excitations as resources for quantum rotation sensing.

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arXiv2026

Loss-induced quantum nonreciprocity and entanglement in superconducting qubits

Losses are ubiquitous in physics and are usually regarded as harmful in quantum information processing. Here, we propose a loss-induced scheme to achieve nonreciprocity and nonreciprocal entanglement in a superconducting platform, where two remote superconducting transmon qubits are connected via two lossy auxiliary cavities. The nonreciprocity in our scheme originates from interference between multiple lossy coupling paths. The coherent phases associated with the qubit-resonator couplings reverse sign under propagation reversal, while the loss-induced phases remain direction independent. Their combined effect leads to different interference conditions in the opposite directions, resulting in unequal effective couplings. We show that this loss-induced scheme can generate nonreciprocal quantum entanglement, indicating that loss can be utilized as a resource. Moreover, the tunability of nonreciprocity and nonreciprocal entanglement in our scheme can be manipulated by the relative phase induced by loss, allowing to tailor both reciprocal and nonreciprocal behaviors. Our results establish a direct link between engineered loss and nonreciprocal entanglement in quantum information processing and offer potential applications in scalable quantum networks.

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arXiv2025

Single photon isolation and nonreciprocal frequency conversion in atom-waveguide systems

In this work, we utilize a two-level atom and a ${\Lambda}$-type atom to link two identical waveguides, subsequently extending the model to a giant-atom configuration. Our analytical solutions and numerical simulations demonstrate that this setup can achieve single-photon isolation and nonreciprocal frequency conversion by tuning the atom-waveguide coupling strengths $g_i$, respectively. We also examine single-photon scattering in the giant-atom model within both the Markovian and non-Markovian regimes. The results reveal that ultranarrow scattering windows are induced by the phases ${\phi}_1$ and ${\phi}_2$ under specific conditions, making them well-suited for precise frequency conversion and sensing. Additionally, in the non-Markovian regime, the spectra exhibit irregular polygonal shapes, offering enhanced opportunities for exploring nonreciprocal frequency conversion in the off-resonant regime. Our work provides a new perspective on achieving optical nonreciprocity at the single-photon level in atom-waveguide systems.

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arXiv2025

Non-Markovian dynamics with ${\Lambda}$-type atomic systems in a single end photonic waveguide

In this work, we investigate the non-Markovian dynamical evolution of a ${\Lambda}$-type atom interacting with a semi-infinite one-dimensional photonic waveguide via two atomic transitions. The waveguide terminates at a perfect mirror, which reflects the light and introduces boundary effects. We derive exact analytical expressions and show that, under suitable conditions, the instantaneous and retarded decay rates reach equilibrium, leading to the formation of an atom-photon bound state that suppresses dissipation. Consequently, the atom retains a long-lived population in the asymptotic time limit. Furthermore, we analyze the output field intensity and demonstrate that blocking one of the coupling channels forces the atomic system to emit photons of a single frequency. Finally, we extend the model to a two-atom system and examine the disentanglement dynamics of the two spatially separated atoms. These findings elucidate the dynamic process of spontaneous emission involving multi-frequency photons from multi-level atoms and provide insights into the complex interference between different decay pathways.

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arXiv2025

Optical nonreciprocity induced by quantum squeezing in temperature sensitive optomechanical systems

We investigate single photon transmission and the statistical properties of photon correlations in $\chi^{(2)}$ microring optomechanical systems, where optical nonreciprocity is induced by directional quantum squeezing. Due to the presence of thermal phonons in the mechanical resonator, the system is highly sensitive to temperature changes. Our numerical simulations show that as the thermal phonons vary from 0 to 10, the isolation ratio of single-photon transmission decreases from 22.2 dB to 1.1 dB (or from -23 dB to -3.3 dB). Additionally, the statistical properties of photon correlations transition from exhibiting a strong bunching effect to a weak bunching effect. Moreover, the parametric amplification component enhances the device's temperature response, distinguishing it from other similar nonreciprocal devices. Our protocol suggests a potential application for nonreciprocal setups in precise temperature measurement at ultralow temperatures, thereby enriching quantum networks and quantum information processing.

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arXiv2024

Nonreciprocal interaction and entanglement between two superconducting qubits

Nonreciprocal interaction between two spatially separated subsystems plays a crucial role in signal processing and quantum networks. Here, we propose an efficient scheme to achieve nonreciprocal interaction and entanglement between two qubits by combining coherent and dissipative couplings in a superconducting platform, where two coherently coupled transmon qubits simultaneously interact with a transmission line waveguide. The coherent interaction between the transmon qubits can be achieved via capacitive coupling or via an intermediary cavity mode, while the dissipative interaction is induced by the transmission line via reservoir engineering. With high tunability of superconducting qubits, their positions along the transmission line can be adjusted to tune the dissipative coupling, enabling to tailor reciprocal and nonreciprocal interactions between the qubits. A fully nonreciprocal interaction can be achieved when the separation between the two qubits is $(4n+3)\lambda_{0} /4$, where $n$ is an integer and $\lambda_{0}$ is the photon wavelength. This nonreciprocal interaction enables the generation of nonreciprocal entanglement between the two transmon qubits. Furthermore, applying a drive field to one of the qubit can stabilize the system into a nonreciprocal steady-state entangled state. Remarkably, the nonreciprocal interaction in this work does not rely on the presence of nonlinearity or complex configurations, which has more potential applications in designing nonreciprocal quantum devices, processing quantum information, and building quantum networks.

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arXiv2024

Skyrmion-mechanical hybrid quantum systems: Manipulation of skyrmion qubits via phonons

Skyrmion qubits are a new highly promising logic element for quantum information processing. However, their scalability to multiple interacting qubits remains challenging. We propose a hybrid quantum setup with skyrmion qubits strongly coupled to nanomechanical cantilevers via magnetic coupling, which harnesses phonons as quantum interfaces for the manipulation of distant skyrmion qubits. A linear drive is utilized to achieve the modulation of the stiffness coefficient of the cantilever, resulting in an exponential enhancement of the coupling strength between the skyrmion qubit and the mechanical mode. We also consider the case of a topological resonator array, which allows us to study interactions between skyrmion qubits and topological phonon band structure, as well as chiral skyrmion-skyrmion interactions. The scheme suggested here offers a fascinating platform for investigating quantum information processing and quantum simulation with magnetic microstructures.

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