7,743 research outputs found

    Nanosecond quantum state detection in a current biased dc SQUID

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    This article presents our procedure to measure the quantum state of a dc SQUID within a few nanoseconds, using an adiabatic dc flux pulse. Detection of the ground state is governed by standard macroscopic quantum theory (MQT), with a small correction due to residual noise in the bias current. In the two level limit, where the SQUID constitutes a phase qubit, an observed contrast of 0.54 indicates a significant loss in contrast compared to the MQT prediction. It is attributed to spurious depolarization (loss of excited state occupancy) during the leading edge of the adiabatic flux measurement pulse. We give a simple phenomenological relaxation model which is able to predict the observed contrast of multilevel Rabi oscillations for various microwave amplitudes.Comment: 10 pages, 8 figure

    Decoherence processes in a current biased dc SQUID

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    A current bias dc SQUID behaves as an anharmonic quantum oscillator controlled by a bias current and an applied magnetic flux. We consider here its two level limit consisting of the two lower energy states | 0 \right> and | 1 \right>. We have measured energy relaxation times and microwave absorption for different bias currents and fluxes in the low microwave power limit. Decoherence times are extracted. The low frequency flux and current noise have been measured independently by analyzing the probability of current switching from the superconducting to the finite voltage state, as a function of applied flux. The high frequency part of the current noise is derived from the electromagnetic environment of the circuit. The decoherence of this quantum circuit can be fully accounted by these current and flux noise sources.Comment: 4 pages, 4 figure

    Hubungan Tingkat Kecemasan Dengan Mekanisme Koping Pada Pasien Ckd (Chronic Kidney Disease) Yang Menjalani Hemodialisa Di RS Condong Catur YOGYAKARTA.

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    Latar Belakang : Gagal ginjal kronik merupakan gangguan fungsi renal dimana kemampuan tubuhgagal untuk mempertahankan metabolisme, keseimbangan cairan dan elektrolit. Pada pasien gagalginjal sering mengalami khawatir karena kondisi sakit yang dialaminya hal ini dapat menjadi stressorfisik yang mampu mengarahkan pasien pada tingkat stress, cemas bahkan depresi. Pada saatmenghadapi keadaan yang penuh stress pasien gagal ginjal harus beradaptasi dengan stressor. Halyang dilakukan tersebut merupakan bagian dari koping.Tujuan Penelitian : Penelitian ini bertujuan untuk mengetahui hubungan tingkat kecemasan denganmekanisme koping pada pasien CKD ( Chronic Kidney Disease) yang menjalani hemodialisa di RSCondong catur Yogyakarta.Metode Penelitian: Penelitian ini merupakan penelitian non eksperimen dengan rancangan surveyanalitik dengan pendekatan cross sectional yang dilakukan pada bulan Februari- Mei 2016. Populasidalam penelitian ini adalah pasien hemodialisa di RS Condong catur Yogyakarta. Teknik pengambilansampel dengan total sampling, didapat 36 responden. Analisa data yang digunakan adalah chisquare untuk mengetahui hubungan tingkat kecemasan dengan mekanisme koping.Hasil Penelitian: Hasil penelitian ini menunjukan bahwa terdapat hubungan antara tingkatkecemasan dengan mekanisme koping pada pasien CKD yang menjalani hemodialisa di RSCondong catur Yogyakarta, dengan nilai dari chi square 3,333 atau P>0,05.Kesimpulan: Terdapat hubungan antara tingkat kecemasan dengan mekanisme koping pada pasienCKD yang menjalani hemodialisa di RS Condong catur Yogyakarta

    Normal metal to ferromagnetic superconductor tunneling

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    We study the point-contact tunneling between normal metal and ferromagnetic superconductor. In the case of magnon-induced pairing the tunneling conductance is continuous and smooth function of the applied voltage. For small values of the applied voltage the Ohm law holds. We show that one can obtain the magnetization and the superconducting order parameter from the tunneling conduc- tance. In the case of paramagnon-induced superconductivity the tunneling does not depend on the magnetization. We argue that tunneling experiment can unambiguously determine the correct pairing mechanism in the ferromagnetic superconductors.Comment: 6 pages, 4 figur

    Competition of Spin-Fluctuations and Phonons in Superconductivity of ZrZn2

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    It has been long suspected that spin fluctuations in the weak itinerant ferromagnet ZrZn2 may lead to a triplet superconductivity in this material. Here we point out another possibility, a spatially inhomogeneous singlet superconducting state (a Fulde-Ferrell-Larkin-Ovchinnikov state). We report detailed electronic structure calculations, as well as calculations of the zone center phonons and their coupling with electrons. We find that the exchange splitting is nonuniform and may allow for gap formation at some parts of the Fermi surface. We also find that there is substantial coupling of Zr rattling modes with electrons, which can, in principle, provide the necessary pairing in the s-channel.Comment: 4 pages, embedded color postscript figures. JPEG versions available from the author

    A Model for Superconductivity in Ferromagnetic ZrZn2

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    This article proposes that superconductivity in the ferromagnetic state of ZrZn2_2 is stabilized by an exchange-type interaction between the magnetic moments of triplet-state Cooper pairs and the ferromagnetic magnetization density. This explains why superconductivity occurs in the ferromagnetic state only, and why it persists deep into the ferromagnetic state. The model of this article also yields a particular order parameter symmetry, which is a prediction that can be checked experimentally.Comment: 4 pages, revised version accepted in PR

    Menelaus relation and Fay's trisecant formula are associativity equations

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    It is shown that the celebrated Menelaus relation and Fay's trisecant formula similar to the WDVV equation are associativity conditions for structure constants of certain three-dimensional algebra.Comment: Talk given at the Conference " Mathematics and Physics of Solitons and Integrable Systems", Dijon, 28.6-2.7, 2009. Minor misprints correcte
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