[Correlation of clinical joint function with histopathological features of knee joint fibrosis].

Objective: To investigate the correlation between the joint function and the histologic grading after total knee arthroplasty, to aid in the early diagnosis and prognostication of arthrofibrosis. Methods: A total of 29 patients including 22 females and 7 males were enrolled retrospectively from October 2015 to October 2020. These patients had a mean age of 63 years (range 41 to 79 years) and underwent total knee revision in Jishuitan Hospital due to joint contraction or loss of range of motion. Histologic assessment was carried out by utilizing immunohistochemistry (IHC) and the Masson staining to evaluate the fibrosis and inflammation of the samples. Results: By light microscopy, early stage arthrofibrosis showed massive proliferation of myofibroblasts and fibroblasts with SMA expression by IHC. In late stage arthrofibrosis, hyaline degeneration occured with extensive hyperplasia of fibrosis-related tissue. The arthrofibrosis samples appeared blue with Masson staining. Lymphocytes showed perivascular distribution. The arthrofibrosis tissue was mostly grade 3 (26 samples) in histologic assessment, moderate grade (25 samples) in ALVAL score, and grade 1 (23 samples) in lymphocyte grading. Fibrosis grading showed an overwhelming correlation with range of motion (ROM) of the joint. The ALVAL score was highly correlated with the WOMAC score. There was also a direct correlation between inflammatory cell infiltration and pain. The fibrosis grading joint with ALVAL score showed a good predictive value of joint function after joint replacement surgery. Conclusions: The histologic assessment score is closely correlated to the joint function with predictive values for the prognosis after joint replacement surgery.

Optimal charging of open spin-chain quantum batteries via homodyne-based feedback control.

We study the problem of charging a dissipative one-dimensional XXX spin-chain quantum battery using local magnetic fields in the presence of spin decay. The introduction of quantum feedback control based on homodyne measurement contributes to improving various performances of the quantum battery, such as energy storage, ergotropy, and effective space utilization rate. For the zero-temperature environment, there is a set of optimal parameters to ensure that the spin-chain quantum battery can be fully charged and the energy stored in the battery can be fully extracted under the perfect measurement condition, which is found through the analytical calculation of a simple two-site spin-chain quantum battery and further verified by numerical simulation of a four-site spin-chain counterpart. For completeness, the adverse effects of imperfect measurement, anisotropic parameter, and finite temperature on the charging process of the quantum battery are also considered.

Stable charging of a Rydberg quantum battery in an open system.

The charging of an open quantum battery is investigated where the charger and the quantum battery interact with a common environment. At zero temperature, the stored energy of the battery is optimal as the charger and the quantum battery share the same coupling strength (g_{C}=g_{B}). By contrast, in the presence of the quantum jump-based feedback control, the energy stored in the battery can be greatly enhanced for different couplings (g_{C}>g_{B}). Considering the feasibility of the experiment, a model of Rydberg quantum battery is proposed with cascade-type atoms interacting with a dissipative optical cavity. The effective coupling strength between the charger (quantum battery) and the cavity field is hence adjustable and one can make the battery close to perfect excitation. The adverse factors of charging quantum batteries such as time delay for feedback, finite temperature, and spontaneous emission of Rydberg atoms are also discussed, and the result shows that the quantum battery is still able to retain a satisfactory energy storage effect.

Rapid population transfer of a two-level system by a polychromatic driving field.

We propose a simple exact analytical solution for a model consisting of a two-level system and a polychromatic driving field. It helps us to realize a rapid complete population transfer from the ground state to the excited state, and the system can be stable at the excited state for an extremely long time. A combination of the mechanism and the Rydberg atoms successfully prepares the Bell state and multipartite W state, and the experimental feasibility is discussed via the current experimental parameters. Finally, the simple exact analytical solution is generalized into a three-level system, which leads to a significant enhancement of the robustness against dissipation.

Robust generation of entangled state via ground-state antiblockade of Rydberg atoms.

We propose a mechanism of ground-state antiblockade of Rydberg atoms, which is then exploited to prepare two-atom entangled state via three different kinds of pulses. First we use the pulses in the form of sin2 and cos2 functions and obtain a maximally entangled state at an accurate interaction time. Then the method of stimulated Raman adiabatic passage (STIRAP) is adopted for the entanglement generation, which is immune to the fluctuations of revelent parameters but requires a long time. Finally we capitalize the advantages of the former two methods and employ shortcuts to adiabatic passage (STAP) to generate the maximal entanglement. The strictly numerical simulation reveals that the current scheme is robust against spontaneous emission of atoms due to the virtual excitation of Rydberg states, and all of the above methods favor a high fidelity with the present experimental technology.

Conversion of entangled states with nitrogen-vacancy centers coupled to microtoroidal resonators.

We propose efficient schemes for converting three-photon, four-photon and five-photon GHZ state to a W state or Dicke state, respectively with the nitrogen-vacancy (N-V) centers via single-photon input-output process and cross-Kerr nonlinearities. The total success probability can be improved by iterating the conversion process for the case of three-photon and five-photon while it does not require iteration for converting four-photon GHZ state to a W state. The analysis of feasibility shows that our scheme is feasible for current experimental technology.

Fusing atomic W states via quantum Zeno dynamics.

We propose a scheme for preparation of large-scale entangled W states based on the fusion mechanism via quantum Zeno dynamics. By sending two atoms belonging to an n-atom W state and an m-atom W state, respectively, into a vacuum cavity (or two separate cavities), we may obtain a (n + m - 2)-atom W state via detecting the two-atom state after interaction. The present scheme is robust against both spontaneous emission of atoms and decay of cavity, and the feasibility analysis indicates that it can also be realized in experiment.

Quantum phase transition in a coupled two-level system embedded in anisotropic three-dimensional photonic crystals.

The quantum phase transition (QPT) describes a sudden qualitative change of the macroscopic properties mapped from the eigenspectrum of a quantum many-body system. It has been studied intensively in quantum systems with the spin-boson model, but it has barely been explored for systems in coupled spin-boson models. In this paper, we study the QPT with coupled spin-boson models consisting of coupled two-level atoms embedded in three-dimensional anisotropic photonic crystals. The dynamics of the system is derived exactly by means of the Laplace transform method, which has been proven to be equivalent to the dissipationless non-Markovian dynamics. Drawing on methods for analyzing the ground state, we obtain the phase diagrams through two exact critical equations and two QPTs are found: one QPT is that from the phase without one bound state to the phase with one bound state and another is that from one phase with the bound state having one eigenvalue to another phase where the bound state has two eigenvalues. Our analytical results also suggest a way of control to overcome the effect of decoherence by engineering the spectrum of the reservoirs to approach the non-Markovian regime and to form the bound state of the whole system for quantum devices and quantum statistics.

General response formula and application to topological insulator in quantum open system.

It is well-known that the quantum linear response theory is based on the first-order perturbation theory for a system in thermal equilibrium. Hence, this theory breaks down when the system is in a steady state far from thermal equilibrium and the response up to higher order in perturbation is not negligible. In this paper, we develop a nonlinear response theory for such quantum open system. We first formulate this theory in terms of general susceptibility, after which we apply it to the derivation of Hall conductance for open system at finite temperature. As an example, the Hall conductance of the two-band model is derived. Then we calculate the Hall conductance for a two-dimensional ferromagnetic electron gas and a two-dimensional lattice model. The calculations show that the transition points of topological phase are robust against the environment. Our results provide a promising platform for the coherent manipulation of the nonlinear response in quantum open system, which has potential applications for quantum information processing and statistical physics.

Genetic evidence for domestic raccoon dog rabies caused by Arctic-like rabies virus in Inner Mongolia, China.

An outbreak of rabies affected domestic raccoon dogs on an animal farm in Inner Mongolia, China in 2007. A study was conducted to characterize the aetiological agent and clarify the origin of the rabies virus. Brain tissues were obtained from five rabid raccoon dogs. Viral nucleoprotein antigen was detected in the brain tissues and five rabies viruses were isolated from these rabid animals. Phylogenetic analysis of the N and G gene sequences showed that these isolates were closely related to Arctic-like rabies viruses isolated from the far-eastern region of Russia and South Korea, but distinct from the rabies viruses that are widely distributed in endemic areas in China. Epidemiological data suggested that the likely source of infection was from one wild raccoon dog that was captured and placed in the same type of pen used for domestic raccoon dogs.