arXiv subjects

Zhi-Rong Zhong

Publications and source records attributed to Zhi-Rong Zhong.

9 recordsLinked to original sources

arXiv2026

Manipulation of Arbitrary-Order Cavity-Magnon Polariton Blockade

Manipulating the cavity-magnon polariton blockade is significant for achieving precise, on-demand control of individual photons (magnons) and has particular applications in realizing multifunctional quantum technologies, quantum information processing, and hybrid quantum networks. In this paper, we theoretically propose a scheme to realize an $n$-cavity-magnon polariton blockade in a cavity-magnon system by utilizing Kerr nonlinearity. We demonstrate that the Kerr nonlinearity introduces anharmonicity into the polariton energy spectrum, which in turn enables the blockade effect. When the external driving frequency is resonant with the transition to the $n$th polariton excited state, a perfect $n$-polariton blockade is achieved. Moreover, increasing the driving strength can enhance the higher-order blockade while maintaining high fidelity in a dissipative environment. Our work pioneers the field of cavity-magnon polariton blockade, opens a new avenue for the preparation of controllable quantum resources, and holds significant potential for applications in quantum communication and quantum information processing.

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arXiv2026

Squeezing-enhanced dual-channel interference for ground-state cooling of a levitated micromagnet with low quality factor

Cooling the center-of-mass (CM) motion of a macroscopic oscillator to its quantum ground state is a fundamental prerequisite for testing quantum mechanics at macroscopic scales. However, achieving this goal is currently hindered by the stringent requirement for an ultrahigh mechanical quality factor ($Q_c$). Here, we propose a dual-channel cooling scheme based on squeezing-enhanced quantum interference within a hybrid levitated cavity-magnomechanical system to overcome this limitation. By synergizing squeezing effects with quantum interference between the magnon-CM and cavity-CM channels, our scheme simultaneously suppresses Stokes (heating) scattering while enhancing anti-Stokes (cooling) scattering.~We demonstrate that this cooling mechanism reduces the critical $Q_c$ required for ground-state cooling by three orders of magnitude, making it achievable in the experimentally accessible regime of $Q_c \sim 10^4$. Furthermore, the net cooling rate is enhanced by nearly 180-fold compared to that of conventional single-channel cooling. This improvement is accompanied by a two orders of magnitude reduction in both the steady-state CM occupancy and the cooling time. Importantly, this enhanced performance remains robust even deep within the unresolved-sideband regime. Our results provide a feasible path toward preparing macroscopic quantum states by actively controlling the cooling dynamics, thereby relaxing the constraints on intrinsic material properties.

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arXiv2025

Nonreciprocal transmission in a cavity-magnon system by rotational Sagnac effect

Ultrahigh nonreciprocal transmission has been achieved in a cavity-magnon system, which consists of two whispering gallery modes (WGMs) and a single magnon mode within a magnetic insulator yttrium iron garnet sphere. The nonreciprocal frequency shift induced by the Sagnac effect enables unidirectional transmission of an input field, while suppressing propagation in the opposite direction, thereby facilitating nonreciprocal optical transmission. Within experimentally accessible parameter regimes, the optical isolation ratio can exceed 40 dB, representing the highest isolation ratio reported to date. Furthermore, applying squeezing to the magnon mode further enhances this isolation performance. Additionally, the directionality of light isolation can be reversed simply by modifying the rotation of the WGM cavity. These findings offer promising prospects for developing high-performance, tunable, and compact optical nonreciprocal devices.

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arXiv2025

Quantum gyroscope based on the cavity magnomechanical system

High-precision rotational angle measurement in noise-prone environments holds critical impor tance in aerospace engineering, military navigation, and related domains. In this paper, we propose a quantum gyroscope scheme based on a cavity magnomechanical system, which enables high precision rotation angle detection by harnessing hybrid light-magnon interactions. Central to this framework is the employment of a two-mode squeezed coherent state, generated via parametric coupling of dual quantized optical fields with collective spin excitations (magnons), serving as the quantum metrological probe. We demonstrate that this scheme can significantly reduce quantum noise to levels far below the shot-noise limit. Furthermore, in the non-Markovian case, the per formance of the quantum gyroscope in a dissipative environment does not deteriorate over time, provided that the environmental spectral density satisfies certain conditions. These findings provide critical insights for advancing miniaturized quantum gyroscopes with sub-microradian precision, addressing long-standing challenges in inertial navigation systems under strong ambient noise.

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arXiv2019

Deterministic entanglement swapping in a superconducting circuit

Entanglement swapping, the process to entangle two particles without coupling them in any way, is one of the most striking manifestations of the quantum-mechanical nonlocal characteristic. Besides fundamental interest, this process has applications in complex entanglement manipulation and quantum communication. Here we report a high-fidelity, unconditional entanglement swapping experiment in a superconducting circuit. The measured concurrence characterizing the qubit-qubit entanglement produced by swapping is above 0.75, confirming most of the entanglement of one qubit with its partner is deterministically transferred to another qubit that has never interacted with it. We further realize delayed-choice entanglement swapping, showing whether two qubits previously behaved as in an entangled state or as in a separable state is determined by a later choice of the type of measurement on their partners. This is the first demonstration of entanglement-separability duality in a deterministic way.

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arXiv2019

Generation and stabilization of entangled coherent states for the vibrational modes of a trapped ion

We propose a scheme for preparation of entangled coherent states for the motion of an ion in a two-dimensional anisotropic trap. In the scheme, the ion is driven by four laser beams along different directions in the ion trap plane, resulting in carrier excitation and couplings between the internal and external degrees of freedom. When the total quantum number of the vibrational modes initially has a definite parity, the competition between the unitary dynamics and spontaneous emission will force the system to evolve to a steady state, where the vibrational modes are in a two-mode cat state. We show that the method can be extended to realization of entangled coherent states for three vibrational modes of an ion in a three-dimensional anisotropic trap.

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arXiv2019

Nearly maximal violation of the Mermin-Klyshko inequality with multimode entangled coherent states

Entangled coherent states for multiple bosonic modes, also referred to as multimode cat states, not only are of fundamental interest, but also have practical applications. The nonclassical correlation among these modes is well characterized by the violation of the Mermin-Klyshko inequality. We here study Mermin-Klyshko inequality violations for such multi-mode entangled states with rotated quantum-number parity operators. Our results show that the Mermin-Klyshko signal obtained with these operators can approach the maximal value even when the average quantum number in each mode is only 1, and the inequality violation exponentially increases with the number of entangled modes. The correlations among the rotated parities of the entangled bosonic modes are in distinct contrast with those among the displaced parities, with which a nearly maximal Mermin-Klyshko inequality violation requires the size of the cat state to be increased by about 15 times.

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arXiv2019

Quantum nonlocality for entanglement of quasiclassical states

Entanglement of quasiclassical (coherent) states of two harmonic oscillators leads to striking quantum effects and is useful for quantum technologies. These effects and applications are closely related to nonlocal correlations inherent in these states, manifested by the violation of Bell inequalities. With previous frameworks, this violation is limited by the size of the system, which does not approach the maximum even when the amount of entanglement approaches its maximum. Here we propose a new version of Bell correlation operators, with which a nearly maximal violation can be obtained as long as the associated entanglement approximates to the maximum. Consequently, the revealed nonlocality is significantly stronger than those with previous frameworks for a wide range of the system size. We present a new scheme for realizing the gate necessary for measurement of the nonlocal correlations. In addition to the use in test of quantum nonlocality, this gate is useful for quantum information processing with coherent states

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arXiv2017

Towards quantum entanglement of micromirrors via a two-level atom and radiation pressure

We propose a method to entangle two distant vibrating microsize mirrors (i.e., mechanical oscillators) in a cavity optomechanical system. In this scheme, we discuss both the resonant and large-detuning conditions, and show that the entanglement of two mechanical oscillators can be achieved with the assistance of a two-level atom and cavity-radiation pressure. In the resonant case, the operation time is relatively short, which is desirable to minimize the effects of decoherence. While in the large-detuning case, the cavity is only virtually excited during the interaction. Therefore, the decay of the cavity is effectively suppressed, which makes the efficient decoherence time of the cavity to be greatly prolonged. Thus, we observe that this virtual-photon process of microscopic objects may induce the entanglement of macroscopic objects. Moreover, in both cases, the generation of entanglement is deterministic and no measurements on the atom and the cavity are required. These are experimentally important. Finally, the decoherence effect and the experimental feasibility of the proposal are briefly discussed.

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