RESUMEN
Stationary quantum correlation among two-level systems (TLSs) in steady state is one of unique resources for applications in quantum information processing. Here we propose a scheme to generate such quantum correlation among the TLSs inside a lossy cavity. It is found that, by applying a broadband squeezed laser acting as a squeezed-vacuum reservoir to the cavity, a stable quantum correlation of the TLSs can be generated. By adiabatically eliminating the cavity field, we derive a reduced master equation of the TLSs in the bad-cavity limit. We show that the generated quantum correlation is essentially determined by the squeezing features transferred from the squeezed-vacuum reservoir via the cavity field as a quantum bus. We study the effect of the system parameters, such as the squeezing, the detuning, the coupling strength, and the decay rate of the TLSs, on the performance of the scheme. The feasibility of our proposal is supported by the application of currently available experimental techniques.
RESUMEN
We investigated the thermoelectric properties of phenalenyl-based molecular devices by using the non-equilibrium Green's function method combined with density function theory. The results show that the thermoelectric performance of molecular device can be significantly improved by different contact geometries. The ZT value of the device can reach 1.2 at room temperature, which is two orders of magnitude higher than that of graphene. Moreover, the change of the coupling between molecule and electrodes can also enhance the ZT value. The ZT value can be further optimized to 1.4 at 300 K and 5.9 at 100 K owing to the decrease of electronic thermal conductance and almost unchanged power factor.
RESUMEN
We explore controllable quantum dynamics of a hybrid system, which consists of an array of mutually coupled superconducting resonators (SRs) with each containing a nitrogen-vacancy center spin ensemble (NVE) in the presence of inhomogeneous broadening. We focus on a three-site model, which compared with the two-site case, shows more complicated and richer dynamical behavior, and displays a series of damped oscillations under various experimental situations, reflecting the intricate balance and competition between the NVE-SR collective coupling and the adjacent-site photon hopping. Particularly, we find that the inhomogeneous broadening of the spin ensemble can suppress the population transfer between the SR and the local NVE. In this context, although the inhomogeneous broadening of the spin ensemble diminishes entanglement among the NVEs, optimal entanglement, characterized by averaging the lower bound of concurrence, could be achieved through accurately adjusting the tunable parameters.
RESUMEN
We investigate the dynamics of quantum correlation between two separated nitrogen vacancy centers (NVCs) placed near a one-dimensional plasmonic waveguide. As a common medium of the radiation field of NVCs propagating, the plasmonic waveguide can dynamically induce quantum correlation between the two NVCs. It is interesting to find that such dynamically induced quantum correlation can be preserved in the long-time steady state by locally applying individual driving on the two NVCs. In particular, we also show that a large degree of quantum correlation can be established by this scheme even when the distance between the NVCs is much larger than their operating wavelength. This feature may open new perspectives for devising active decoherence-immune solid-state optical devices and long-distance NVC-based quantum networks in the context of plasmonic quantum electrodynamics.
RESUMEN
Extra-adrenal pheochromocytomas are rare tumors that originate from the chromaffin tissue of the sympathetic nervous system. Ovarian extra-adrenal pheochromocytoma is even more rare. The present study reports a rare case of an extra-adrenal pheochromocytoma that was localized to the right ovary, but was gynecologically asymptomatic. Computed tomography angiography (CTA) detected the tumor and indicated that it was well defined, highly vascularized and obtained its blood supply from the right ovarian artery. This is the second case of ovarian extra-adrenal pheochromocytoma reported in the literature, and the first description of the CTA manifestations in the ovary. Gynecologists and radiologists should consider the possibility that an ovarian mass could be an extra-adrenal pheochromocytoma, which would allow time to prepare appropriately for the surgical removal of the mass.
RESUMEN
OBJECTIVE: To evaluate the value of "low-signal zone" sign in the diagnosis of brain abscess in the capsule period. METHODS: The conventional MRI was performed pre-therapy in 21 patients with brain abscess in the capsule period and 25 patients with vesica-astrocytomas. We analyzed the pathologic basis of "low-signal zone" sign in brain abscess and compared the frequency and shape of "low-signal zone" sign in brain abscess and vesica-astrocytomas. RESULTS: The "low-signal zone" sign in MRI occurred more frequently in brain abscess (85.7%, 18/21) than in vesica-astrocytomas (52.0%, 13/25). The "low-signal zone" sign in the former was intact, while that in the latter was not. CONCLUSION: The "low-signal zone" sign is helpful to diagnose brain abscess in the capsule period, and is valuable to differentiate brain abscess and vesica-astrocytomas.