Effects of edge disorder on the stability of quantum oscillations in two-dimensional coupled systems.

This paper utilizes the theory of quantum diffusion to analyze the electron probability and spreading width of a wavepacket on each layer in a two-dimensional (2D) coupled system with edge disorder, aiming to clarify the effects of edge disorder on the stability of the electron periodic oscillations in 2D coupled systems. Using coupled 2D square lattices with edge disorder as an example, we show that, the electron probability and wavepacket spreading width exhibit periodic oscillations and damped oscillations, respectively, before and after the wavepacket reaches the boundary. Furthermore, these electron oscillations exhibit strong resistance against disorder perturbation with a longer decay time in the regime of large disorder, due to the combined influences of ordered and disordered site energies in the central and edge regions. Finally, we numerically verified the universality of the results through bilayer graphene, demonstrating that this anomalous quantum oscillatory behavior is independent of lattice geometry. Our findings are helpful in designing relevant quantum devices and understanding the influence of edge disorder on the stability of electron periodic oscillations in 2D coupled systems.

Hedgehog receptors exert immune-surveillance roles in the epidermis across species.

Hedgehog signaling plays pivotal roles in the development and homeostasis of epithelial barrier tissues. However, whether and how Hedgehog signaling directly regulates innate immunity in epithelial cells remains unknown. By utilizing C. elegans epidermis as the model, we found that several Hedgehog receptors are involved in cell-autonomous regulation of the innate immune response in the epidermis. Particularly, loss of the Patched family receptor induces aberrant up-regulation of epidermal antimicrobial peptides in a STAT-dependent manner. External or internal insult to the epidermis triggers rapid rearrangement of Patched distribution along the plasma membrane, indicating that the Hedgehog (Hh) receptor is likely involved in recognition and defense against epidermal damage. Loss of PTCH1 function in primary human keratinocytes and intact mouse skin also results in STAT-dependent immune activation. These findings reveal an evolutionally conserved immune-surveillance function of Hedgehog receptors and an insult-sensing and response strategy of epithelial tissues.

Analysis of factors contributing to postoperative body weight change in patients with gastric cancer: based on generalized estimation equation.

AIMS: The study aimed to explore factors contributing to body weight change over time in gastric cancer patients after gastrectomy, in order to find risk factors to implement nutritional intervention beforehand. METHODS: A cohort of gastric cancer patients who were treated with gastrectomy from January to March 2019 at a university affiliated hospital in Shanghai were consecutively identified in this study. Demographics, disease related information, nutrition knowledge, attitude, and practice score were collected before gastrectomy. In addition, body weight before surgery (T0), body weight at one month (T1), two months (T2), and three months (T3) after gastrectomy were recorded. Generalized estimation equation was used to describe body weight change and analyze factors contributing to body weight change after surgery. RESULTS: There were 49 patients recruited in the study. Patient body weight decreased by 9.2% at T1 (Wald χ = 271.173, P <0.001), 11.0% at T2 (Wald χ 2 = 277.267, P <0.001), and 11.4% at T3 compared to baseline at T0 (Wald χ = 284.076, P <0.001). The results of GEE for multivariable analysis showed that surgery type (Wald χ = 6.027, P = 0.014) and preoperative BMI (Wald χ = 12.662, P = 0.005) were contributing factors of body weight change. Compared with distal gastrectomy patients, total gastrectomy patients experienced greater body weight loss (ß = 2.8%, P = 0.014). Compared with patients with BMI&λτ; 18.5 kg/m2, patients with BMI ≥ 25 kg/m2experienced greater body weight loss (ß = 4.5% P = 0.026). CONCLUSION: Gastric cancer patients experienced significant weight loss during 3 months after gastrectomy. Total gastrectomy and BMI ≥ 25 kg/m2were risk factors to postoperative body weight loss for GC patients. The results suggested hinted that clinician should pay attention to postoperative nutrition status of patient undergoing total gastrectomy and obesity patients.

Transferring arbitrary d-dimensional quantum states of a superconducting transmon qudit in circuit QED.

A qudit (d-level quantum system) has a large Hilbert space and thus can be used to achieve many quantum information and communication tasks. Here, we propose a method to transfer arbitrary d-dimensional quantum states (known or unknown) between two superconducting transmon qudits coupled to a single cavity. The state transfer can be performed by employing resonant interactions only. In addition, quantum states can be deterministically transferred without measurement. Numerical simulations show that high-fidelity transfer of quantum states between two superconducting transmon qudits (d ≤ 5) is feasible with current circuit QED technology. This proposal is quite general and can be applied to accomplish the same task with natural or artificial atoms of a ladder-type level structure coupled to a cavity or resonator.

Generation of a macroscopic entangled coherent state using quantum memories in circuit QED.

W-type entangled states can be used as quantum channels for, e.g., quantum teleportation, quantum dense coding, and quantum key distribution. In this work, we propose a way to generate a macroscopic W-type entangled coherent state using quantum memories in circuit QED. The memories considered here are nitrogen-vacancy center ensembles (NVEs), each located in a different cavity. This proposal does not require initially preparing each NVE in a coherent state instead of a ground state, which should significantly reduce its experimental difficulty. For most of the operation time, each cavity remains in a vacuum state, thus decoherence caused by the cavity decay and the unwanted inter-cavity crosstalk are greatly suppressed. Moreover, only one external-cavity coupler qubit is needed, which simplifies the circuit.

Multi-target-qubit unconventional geometric phase gate in a multi-cavity system.

Cavity-based large scale quantum information processing (QIP) may involve multiple cavities and require performing various quantum logic operations on qubits distributed in different cavities. Geometric-phase-based quantum computing has drawn much attention recently, which offers advantages against inaccuracies and local fluctuations. In addition, multiqubit gates are particularly appealing and play important roles in QIP. We here present a simple and efficient scheme for realizing a multi-target-qubit unconventional geometric phase gate in a multi-cavity system. This multiqubit phase gate has a common control qubit but different target qubits distributed in different cavities, which can be achieved using a single-step operation. The gate operation time is independent of the number of qubits and only two levels for each qubit are needed. This multiqubit gate is generic, e.g., by performing single-qubit operations, it can be converted into two types of significant multi-target-qubit phase gates useful in QIP. The proposal is quite general, which can be used to accomplish the same task for a general type of qubits such as atoms, NV centers, quantum dots, and superconducting qubits.

Efficient transfer of an arbitrary qutrit state in circuit quantum electrodynamics.

Compared with a qubit, a qutrit (i.e., three-level quantum system) has a larger Hilbert space and thus can be used to encode more information in quantum information processing and communication. Here, we propose a method to transfer an arbitrary quantum state between two flux qutrits coupled to two resonators. This scheme is simple because it only requires two basic operations. The state-transfer operation can be performed fast because only resonant interactions are used. Numerical simulations show that the high-fidelity transfer of quantum states between the two qutrits is feasible with current circuit-QED technology. This scheme is quite general and can be applied to accomplish the same task for other solid-state qutrits coupled to resonators.

Efficient scheme for generation of photonic NOON states in circuit QED.

We propose an efficient scheme for generating photonic NOON states of two resonators coupled to a four-level superconducting flux device (coupler). This proposal operates essentially by employing a technique of a coupler resonantly interacting with two resonators simultaneously. As a consequence, the NOON-state preparation requires only N+1 operational steps and thus is much faster when compared with a recent proposal [Su et al, Sci. Rep.4, 3898 (2014)] requiring 2N steps of operation. Moreover, due to the use of only two resonators and a coupler, the experimental setup is much simplified when compared with previous proposals requiring three resonators and two superconducting qubits/qutrits.