2,577 research outputs found

    Buckyball Quantum Computer: Realization of a Quantum Gate

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    We have studied a system composed by two endohedral fullerene molecules. We have found that this system can be used as good candidate for the realization of Quantum Gates Each of these molecules encapsules an atom carrying a spin,therefore they interact through the spin dipole interaction. We show that a phase gate can be realized if we apply on each encased spin static and time dependent magnetic field. We have evaluated the operational time of a π\pi-phase gate, which is of the order of ns. We made a comparison between the theoretical estimation of the gate time and the experimental decoherence time for each spin. The comparison shows that the spin relaxation time is much larger than the π\pi-gate operational time. Therefore, this indicates that, during the decoherence time, it is possible to perform some thousands of quantum computational operations. Moreover, through the study of concurrence, we get very good results for the entanglement degree of the two-qubit system. This finding opens a new avenue for the realization of Quantum Computers.Comment: 13 pages, 5 figures. Submitted to Physical Review

    A Complete Noise- and Scattering-Parameters Test-Set

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    Theoretical model for the realization of quantum gates using interacting endohedral fullerene molecules

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    We have studied a physical system composed oftwo interacting endohedral fullerene molecules for quantum computational purposes. The mutual interaction between these two molecules is determined by their spin dipolar interaction. The action of static magnetic fields on the whole system allows us to encode the qubit in the electron spin of the encased atom. We present a theoretical model which enables us to realize single-qubit and twoqubit gates through the system under consideration. Single-qubit operations can be achieved by applying to the system time-dependent microwave fields. Since the dipolar spin interaction couples the two qubit-encoding spins, two-qubit gates are naturally performed by allowing the system to evolve freely. This theoretical model is applied to two realistic architectures of two interacting endohedrals. In the first realistic system the two molecules are placed at a distance of 1.14nm. In the second design the two molecules are separated by a distance of 7nm. In the latter case the condition Δωp > > g(r) is satisfied, i.e. the difference between the precession frequencies of the two spins is much greater than the dipolar coupling strength. This allows us to adopt a simplified theoretical model for the realization of quantum gates. The realization of quantum gates for these realistic systems is provided by studying the dynamics of the system. In this extent we have solved sets of Schrodinger equations needed for reproducing the respective gates, i.e. phase-gate, 1r-gate and CNOT-gate. For each quantum gate reproduced through the realistic. system, we have estimated their reliability by calculating the related fidelity. The presented two-qubit gates are characterized by very high values of fidelity. The value of minimum fidelity related to the realization of a CNOT-gate is F=0.9995, which differs from the ideal value F=1 by of the order of 10⁻ÂČ%. We also present suggestions regarding the improvements on systems composed of endohedral fullerenes in order to enable the experimental realization of quantum gates. This would allow these systems to become reliable building blocks of a quantum computer.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    The application of Geant4 simulation code for brachytherapy treatment

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    Brachytherapy is a radiotherapeutic modality that makes use of radionuclides to deliver a high radiation dose to a well-defined volume while sparing surrounding healthy structures. At the National Institute for Cancer Research of Genova a High Dose Rate remote afterloading system provides Ir(192) endocavitary brachytherapy treatments. We studied the possibility to use the Geant4 Monte Carlo simulation toolkit in brachytherapy for calculation of complex physical parameters, not directly available by experiment al measurements, used in treatment planning dose deposition models

    Primary cutaneous alk positive anaplastic large cell lymphoma in a melanoma patient

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    Primary cutaneous anaplastic large cell lymphoma (PCALCL) is a raresubset of CD30+ lymphoproliferative disorder, characterized by the presenceof large anaplastic cells, which express CD30, CD2, CD3, CD4, and CD5. A 62 year-old male patient presented to our Institute with a history of a fastgrowing and pinkish-brown asymptomatic cutaneous nodule. His medical past history was positive for a malignant melanoma (MM) of the abdomen (0.7 mm Breslow thickness; pT1a). Histologically the lesion showed a diffuse infiltrate consisting in cohesive sheets of large cells with anaplastic morphology with a kidney-shaped nucleus, also known as hallmark cells. Immunohistochemical studies revealed a CD30 expression, and a positivity to perforin and anaplastic lymphoma kinase (ALK). The laboratory and instrumental investigations were all normal and a final diagnosis of PCALCL was made. The patient showed a good response to radiotherapy. Usually PCALCL shares with systemic anaplastic large cell lymphoma (ALCL) the presence of neoplastic CD30+ large T cells, but lack ALK translocations and protein expression. However, the detection of ALK expression in PCALCL should be considered highly suspicious of a cutaneous manifestation of an underlying systemic disease (not detected in our patient). We recommend to exclude a systemic involvement in this kind of disease, with a strict follow-up, especially in patients with double malignancies

    The impact of psychological distress on weight regain in post-bariatric patients during the COVID-19 pandemic: A latent profile analysis

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    Objective: The COVID-19 pandemic has caused a global health crisis disrupting healthcare delivery for people with severe obesity who have undergone bariatric surgery. This study examined the role of psychological distress during the first Italian COVID-19 lockdown in predicting post-operative outcomes in post-bariatric patients reaching the end of the 12-18 months follow-up during the lockdown. By using a person-centered approach, groups of patients with different psychological distress profiles were identified. We hypothesized that compared to post-bariatric patients with low psychological distress, post-bariatric patients with high psychological distress will be more at risk of weight regain. Methods: A total of 67 patients (71.6% female, Mage = 45.9) participated in this observational retrospective cohort study. Patients' anthropometric data were gathered from medical records while the weight at the end of the lockdown through phone interviews. Psychological distress, operationalized with anxiety symptoms, depressive symptoms, and sleep disturbances, was assessed by an online self-report questionnaire. Results: Significant differences were highlighted in the high and low psychological distressed group in weight changes, F(1,58) = 5.2, p < 0.001, η2 = 0.3. Specifically, compared to post-bariatric patients in the low psychological distress group, those in the high psychological distressed group reported weight regained (95% CI = 1.0, 2.6). Conclusion: Results highlight the need to target post-bariatric patients with high psychological distress who are at risk for weight regain during the COVID-19 pandemic. Interventions mitigating psychological distress and obesogenic behaviors during future pandemics or in post-COVID times are needed in vulnerable post-bariatric patients reporting high psychological distress

    Graduate HRD Programs in South Korea

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    The Problem To address national issues associated with societal development, many countries are recognizing the need to educate individuals who will lead developmental initiatives. While many previous studies have been conducted to examine how and what content of human resource development (HRD) has been taught in Western countries, similar research efforts have been rarely conducted in Asian countries such as South Korea. The lack of comparative study creates a research gap in understanding how HRD programs have been designed and implemented in different countries.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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