Entangled atomic ensemble and YIG sphere in coupled microwave cavities

We present a scheme to generate distant bipartite and tripartite entanglement between an atomic ensemble and a yttrium iron garnet (YIG) sphere in coupled microwave cavities. The system we consider has five excitation modes namely cavity-1 photons, atomic ensemble, cavity-2 photons, magnon and phonon modes in YIG sphere. We show that significant bipartite entanglement exists between indirectly coupled subsystems in the cavities, which is robust against temperature. Moreover, we present suitable detuning parameters for a significant tripartite entanglement of ensemble, magnon, and phonon modes. We also demonstrate the existence of tripartite entanglement between magnon and phonon modes of YIG sphere with indirectly coupled cavity photons. Further, we show that cavity-cavity coupling strength affects both the degree and transfer of quantum entanglement between various subsystems. It follows that an appropriate cavity-cavity coupling optimizes the distant entanglement by increasing the entanglement strength and critical temperature for its existence.Comment: 11 pages, 10 figure

Magnomechanically controlled Goos-H\"{a}nchen shift in cavity QED

Phenomena involving interactions among magnons, phonons, and photons in cavity magnomechanical systems have attracted considerable attention recently, owing to their potential applications in the microwave frequency range. One such important effect is the response of a probe field to such tripartite interaction between photon-magnon-phonon. In this paper, we study Goos-H\"{a}nchen shift (GHS) of a reflected probe field in a cavity magnomechanical system. We consider a YIG sphere positioned within a microwave cavity. A microwave control field directly drives the magnon mode in YIG sphere, whereas the cavity is driven via a weak probe field. Our results show that the GHS can be coherently controlled through magnon-phonon coupling via the control field. For instance, GHS can be tuned from positive to negative by tuning the magnon-phonon coupling. Similarly, the effective cavity detuning is another important controlling parameter for GHS. Furthermore, we observe that the enhancement of GHS occurs when magnon-phonon coupling is weak at resonance, and when the magnon-photon coupling is approximately equal to the loss of microwave photons. Our findings may have potential significance in applications related to microwave switching and sensing.Comment: 7 pages, 6 figure

Audit of lymph node biopsies in suspected cases of Lymphoproliferative Malignancies: Implications on tissue diagnosis and patient management

Aims: To carry out an audit ascertaining the importance of condition of lymph node specimen, submission of clinical history including site of biopsy and imrnunohistochemcial studies on conclusiveness of diagnosis made. Methodology: Computer records of the Aga Khan University Hospital, Histopathology Laboratory were used to analyze all cases of lymphoproliferative malignancies presented at the hospital from 1992 to 1998. Results: Out of a total of 466 cases studied, in 283 (61%) the lymph nodes were fragmented. The site of biopsy was mentioned in 361 (77.5%) cases with the cervical region forming the most common site (56.5%). A clinical history was submitted in 395 (85%) and a conclusive diagnosis was reached in 378 (81%) cases. Conclusion: This audit indicates a strong co-relation between the condition of lymph node biopsies received, clinical history of the patient submitted including site of biopsy, acvillary studies like IHC performed on the eventual outcome in the form of precise diagnosis and categorization of lymphoproliferative malignancie

Entangled radiation via a Raman-driven quantum-beat laser

Journals published by the American Physical Society can be found at http://publish.aps.org/We propose a scheme for the entanglement generation of two cavity modes using a four-level Raman-driven quantum-beat laser (QBL). The atomic coherence is generated by a Raman-type two-photon process. Two different sufficient conditions for entanglement generation have been investigated. The effect of cavity losses and strength of the driving fields on entanglement generation is studied for different initial states of the resonant cavity modes. The results are in agreement with the earlier scheme for the entanglement generation using a directly driven quantum-beat laser. We observe entanglement generation even for high cavity losses and with low strength of the driving fields. Further, there is no dipole-forbidden transition in the Raman-driven QBL system. Thus the proposed scheme for the entanglement generation is experimentally more viable as compared to the previous directly driven QBL system

Securing Cognitive Radio Networks using blockchains

Due to the increase in industrial applications of Internet of Things (IoT), number of internet connected devices have been increased accordingly. This has resulted in big challenges in terms of accessibility, scalability, connectivity and adaptability. IoT is capable of creating connections between devices on wireless medium but the utilization of scarce spectrum in efficient manner for the establishment of these connections is the biggest concern. To accommodate spectrum allocation problem different radio technologies are being utilized. One of the most efficient technique being used is cognitive radio, which dynamically allocate the unlicensed spectrum for IoT applications. Spectrum sensing being the fundamental component of Cognitive Radio Network (CRN) is threatened by security attacks. Process of spectrum sensing is disturbed by the malicious user (MU) which attacks the primary signal detection and affects the accuracy of sensing outcome. The presence of such MU in system, sending false sensing data can degrade the performance of cognitive radios. Therefore, in this article a blockchain based method is proposed for the MU detection in network. By using this method an MU can easily be discriminated from a reliable user through cryptographic keys. The efficiency of the proposed mechanism is analyzed through proper simulations using MATLAB. Consequently, this mechanism can be deployed for the validation of participating users in the process of spectrum sensing in CRN for IoTs.publishe