Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system

We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr(CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing(FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.

A nearly deterministic scheme for generation of multiphoton GHZ states with weak cross-Kerr nonlinearity

We propose a scheme to generate polarization-entangled multiphoton Greenberger-Horne^Zeilinger （GHZ） states based on weak cross-Kerr nonlinearity and subsequent homodyne measurement. It can also be generalized to produce maximally N-qubit entangled states. The success probabilities of our schemes are almost equal to 1.

Two-qubit and three-qubit controlled gates with cross-Kerr nonlinearity

Schemes for two-qubit and three-qubit controlled gates based on cross-Kerr nonlinearity are proposed in this paper.The probability of the success of these gates can be increased by quantum nondemolition detectors,which are used to judge which paths the signal photons pass through.These schemes are almost deterministic and require no ancilla photon.The advantages of these gates over the existing ones include less resource consumption and a higher probability of success,which make our schemes more feasible with current technology.

Generation of a four-particle entangled state via cross-Kerr nonlinearity

We propose a scheme for generating a genuine four-particle polarisation entangled state ｜χ^00） that has many interesting entanglement properties and potential applications in quantum information processing. In our scheme, we use the weak cross-Kerr nonlinear interaction between field-modes and the non-demolition measurement method based on highly efficient homodyne detection, which is feasible under the current experiment conditions.

Complete four-photon cluster-state analyzer based on cross-Kerr nonlinearity

We propose a method to construct an optical cluster-state analyzer based on cross-Kerr nonlinearity combined with linear optics elements. In the scheme, we employ two four-qubit parity gates and the controlled phase gate （CPG） from only the cross-Kerr nonlinearity and show that all the orthogonal four-qubit cluster states can be completely identified. The scheme is significant for the large-scale quantum communication and quantum information processing networks. In addition, the scheme is feasible and deterministic under current experimental conditions.

Generation of hyperentangled four-photon cluster state via cross-Kerr nonlinearity

We propose a scheme for generating a hyperentangled four-photon cluster state that is simultaneously entangled in polarization modes and spatial modes. This scheme is based on linear optical elements, weak cross-Kerr nonlinearity, and homodyne detection. Therefore, it is feasible with current experimental technology.

Bidirectional quantum teleportation of unknown photons using path-polarization intra-particle hybrid entanglement and controlled-unitary gates via cross-Kerr nonlinearity

We propose an arbitrary controlled-unitary （CU） gate and a bidirectional quantum teleportation （BQTP） scheme. The proposed CU gate utilizes photonic qubits （photons） with cross-Kerr nonlinearities （XKNLs）, X-homodyne detectors, and linear optical elements, and consists of the consecutive operation of a controlled-path （C-path） gate and a gathering-path （G- path） gate. It is almost deterministic and feasible with current technology when a strong coherent state and weak XKNLs are employed. Based on the CU gate, we present a BQTP scheme that simultaneously teleports two unknown photons between distant users by transmitting only one photon in a path-polarization intra-particle hybrid entangled state. Consequently, it is possible to experimentally implement BQTP with a certain success probability using the proposed CU gate.

Generating a four-photon polarization-entangled cluster state with homodyne measurement via cross-Kerr nonlinearity

We propose a protocol to generate a four-photon polarization-entangled cluster state with cross-Kerr nonlinearity by using the interference of polarized photons. The protocol is based on optical elements, cross-Kerr nonlinearity, and homodyne measurement, therefore it is feasible with current experimental technology, The success probability of our protocol is optimal, this property makes our protocol more efficient than others in the applications of quantum communication.

Bidirectional transfer of quantum information for unknown photons via cross-Kerr nonlinearity and photon-number-resolving measurement

We propose an arbitrary controlled-unitary （CU） gate and a bidirectional transfer scheme of quantum information （BTQI） for unknown photons. The proposed CU gate utilizes quantum non-demolition photon-number-resolving measure- ment based on the weak cross-Kerr nonlinearities （XKNLs） and two quantum bus beams; the proposed CU gate consists of consecutive operations of a controlled-path gate and a gathering-path gate. It is almost deterministic and is feasible with current technology when a strong amplitude of the coherent state and weak XKNLs are employed. Compared with the existing optical multi-qubit or controlled gates, which utilize XKNLs and homodyne detectors, the proposed CU gate can increase experimental realization feasibility and enhance robustness against decoherence. According to the CU gate, we present a BTQI scheme in which the two unknown states of photons between two parties （Alice and Bob） are mutually swapped by transferring only a single photon. Consequently, by using the proposed CU gate, it is possible to experimentally implement the BTQI scheme with a certain probability of success.

Generation of Four-Photon Cluster State with Coherent Light via Cross-Kerr Nonlinearity

We propose two schemes for preparing four-photon cluster state through cross-Kerr nonlinearity. Two coherent fields interact when they enter a nonlinear Kerr medium. If the interaction time is chosen appropriately in each Kerr medium, four-photon cluster state can be generated based on the results of two homodyne detectors in the first scheme. These schemes only use Kerr medium and homodyne measurements on coherent light fields, which can be effciently made in quantum optical laboratories. In addition, weak cross-Kerr nonlinearity is sufficient. All of the properties make these schemes feasible in experiments.

Controllable cross-Kerr interaction between microwave photons in circuit quantum electrodynamics

We propose a scheme to enable a controllable cross-Kerr interaction between microwave photons in a circuit quantum electrodynamics （QED） system. In this scheme we use two transmission-line resonators （TLRs） and one superconducting quantum interference device （SQUID） type charge qubit, which acts as an artificial atom. It is shown that in the dispersive regime of the eircuit-QED system, a controllable cross-Kerr interaction can be obtained by properly preparing the initial state of the qubit, and a large cross-phase shift between two microwave fields in the two TLRs can then be reached. Based on this cross-Kerr interaction, we show how to create a macroscopic entangled state between the two TLRs.

Unconventional photon blockade induced by the self-Kerr and cross-Kerr nonlinearities

We study the use of the self-Kerr and cross-Kerr nonlinearities to realize strong photon blockade in a weakly driven,four-mode optomechanical system.According to the Born–Oppenheimer approximation,we obtain the cavity self-Kerr coupling and the inter-cavity cross-Kerr coupling,adiabatically separated from the mechanical oscillator.Through minimizing the second-order correlation function,we find out the optimal parameter conditions for the unconventional photon blockade.Under the optimal conditions,the strong photon blockade can appear in the strong or weak nonlinearities.

Photonic quantum network transmission assisted by the weak cross-Kerr nonlinearity

Classical network coding permits all internal nodes to encode or decode the incoming messages over proper fields in order to complete a network multicast. Similar quantum encoding scheme cannot be easily followed because of various quantum no-go theorems. In this paper, to avoid these theorems in quantum multiple-source networks, we present a photonic strategy by exploring quantum transferring approaches assisted by the weak cross-Kerr nonlinearity. The internal node may nearly deterministically fuse all incoming photons into a single photon with multiple modes. The fused single photon may be transmitted using twophotonic hyperentanglement as a quantum resource. The quantum splitting as the inverse operation of the quantum fusion allows forwarding quantum states under the quantum no-cloning theorem. Furthermore, quantum addressing schemes are presented to complete the quantum transmissions on multiple-source networks going beyond the classical network broadcasts or quantum n-pair transmissions in terms of their reduced forms.

Influence of pump brightness,self-Kerr and cross-Kerr effects on the entanglement of partially degenerate triple-photon state

Recently,partially degenerate triple-photon states(TPS)generated by the third-order spontaneous parametric down-conversion have been observed in a superconducting cavity(2020,Phys.Rev.X 10,011011).Their non-Gaussian entanglement properties,characterized by a series of high-order covariance matrices,have also been theoretically revealed.Here,we use the non-Gaussian entanglement criterion proposed in(2021,Phy.Rev.Lett.127,150502)and the logarithmic negativity to study the effect of pump brightness,self-Kerr and cross-Kerr interactions on the entanglement of partially degenerate TPS(PDTPS).We find that the brighter the pump,the easier the entanglement of PDTPS leap to higher-order covariance matrices.Although both self-Kerr and cross-Kerr interactions induce nonlinear phase shifts and weaken the entanglement of PDTPS,cross-Kerr interactions can effectively raise the threshold of entanglement loaded on the third-order covariance matrix.These results can contribute to our understanding of the mechanism of the generation of unconditional non-Gaussian entanglement.

Low-light-level spin–orbit splitting via structured light cross-Kerr interaction in coherent atomic media

We explore the spin–orbit coupling(SOC) mechanism for structured light in coherent atomic media with low-light-level cross-Kerr nonlinearity. Using the five-level M-type electromagnetic induced transparency(EIT) system as a prototype, we show that spin–orbit splitting for a weak spinor image can be generated by a weak trigger field carrying orbital angular momentum(OAM) at low-light intensity. By quantum-optical analogy, the paraxial focusing and defocusing of the two pseudo-spin states in the spinor image can be governed by a Pauli-like equation. More importantly, by changing the EIT parameters, especially the topological charge of the weak trigger field, the SOC-induced radial quantization of the spinor image can be rather significant,giving rise to positive or negative OAM-OAM mode separation in free space. This suggests that the separation can be flexibly controlled due to strong image-vortex interaction based on fewphoton cross-Kerr modulation. Our findings may have the potential for all-optical OAM multiplexing and demultiplexing of structured light fields toward few-photon quantum control and multimode communication.

Efficient preparation of a four-photon cluster state with homodyne measurement via cross-Kerr nonlinearity

A scheme is proposed for generating a multiphoton entangled cluster state among four modes. The scheme only uses Kerr medium, beam splitter and homodyne measurements on coherent light fields, which can be efficiently made in quantum optical laboratories. The photon in the signal mode is prepared in a superposition state of the vacuum state and one-photon state while the probe beam is initially set in a coherent state superposition. The strong probe mode interacts successively with multiple signal-mode photons, each causing a conditional phase rotation in the probe mode. Subsequent momentum quadrature homodyne measurement of the probe mode will project the photons in the signal mode into the desired entangled states. It is shown that under certain conditions, the four-photon cluster state can be generated with high fidelity and high success probability, and the scheme is feasible by current experimental technology.

Optical implementation of quantum random walks using weak cross-Kerr media

Weak cross-Kerr media provides additional degrees of freedom of qubits in quantum information processing.In this paper,by exploiting weak cross-Kerr nonlinearity,we propose an optical implementation scheme of one-dimensional quantum random walks. The random walks are described by the interaction of single photons with cross-Kerr media.The proposed scheme can also be used to implement one-dimensional quantum random walks on an infinite line.

交叉克尔非线性对二阶非线性诱导透明的影响

考虑耦合介质存在交叉克尔非线性的情形下,研究了交叉克尔效应对耦合双谐振腔中二阶非线性诱导透明的影响.首先给出了描述体系理论模型的哈密顿量,再通过对海森堡-朗之万方程进行线性化,得到了探测场的透射率,进而得出系统的吸收和色散关系.研究结果表明,在交叉克尔非线性强度较小时,可忽略其对诱导透明的影响;随着交叉克尔非线性强度的增大,诱导透明窗口宽度随之快速变窄.此外,吸收曲线中还出现了双吸收峰.进一步增强交叉克尔非线性,导致原本出现的诱导透明消失,并在新吸收峰处产生了新的诱导透明,新的诱导透明的吸收零点位置随着交叉克尔非线性增加而向左偏移.这些结果可能在不透明介质的窄窗口光传输和提高光学腔的性能方面提供一些参考.

跨关节克氏针交叉内固定术在指骨颈部骨折中的应用效果

目的:探讨跨关节克氏针交叉内固定术在指骨颈部骨折中的应用效果。方法:选取2020年1月-2021年6月我院收治的80例指骨颈部骨折患者为研究对象。依据患者入院编号的奇偶性及不同骨折类型,将中节指骨颈部骨折分为观察组A1与对照组B1,各20例,将近节指骨颈部骨折分为观察组A2与对照组B2,各20例。对照组采用不经过关节克氏针交叉固定术,观察组采用跨关节克氏针交叉内固定术。比较2组术后恢复效果、手术情况。结果:术后6个月,观察组A1优良率为90.00%,高于对照组B1的75.00%,差异有统计学意义(P<0.05)。观察组A2优良率为85.00%,高于对照组B2的70.00%,差异有统计学意义(P<0.05)。观察组A1手术时长短于对照组B1,透视次数少于对照组B1,组间差异有统计学意义(P<0.05)。观察组A2手术时长短于对照组B2,透视次数少于对照组B2,组间差异有统计学意义(P<0.05)。结论:指骨颈部骨折患者采用跨关节克氏针交叉内固定术治疗,可降低手术难度,缩短手术时间,减少透视次数,降低手术对患者指骨及周围软组织的损伤,加快术后恢复速度,降低骨折对患者自身的影响,具有应用价值。

基于弱Kerr非线性相互作用的近乎确定性可控量子隐形传态(英文)

基于cross-Kerr非线性相互作用,提出了一种近似确定性的可控量子隐形传态方案。利用量子非破坏性测量技术较容易地实现了复杂的控制非操作和贝尔态分析过程,这使得此方案比以往使用投影测量的隐形传态方案效率更高,进一步分析表明方案在现有的实验条件下是切实可行的。