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Nb/Al-AlOx/Nb tunnel junctions with controllable critical current density Jc are fabricated using the standard selective Nb etching process.Tunnel barriers are formed in different oxygen exposure conditions (oxygen pressure P and oxidation time t),giving rise to Jc ranging from 100 A/cm2 to above 2000 A/cm2.Jc shows a familiar linear dependence on P × t in logarithmic scales.We calculate the energy levels of the phaseand flux-type qubits using the achievable junction parameters and show that the fabricated Nb/Al-AlOx/Nb tunnel junctions can be used conveniently for quantum computation applications in the future. 相似文献
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An economical magnetocardiogram (MCG) system is built in our laboratory. It mainly consists of a MCG data acquisition stage equipped with two high-To superconducting quantum interference device (SQUID) magnetometers, a data processing stage with digital filtering and a one-layer μ-metal magnetically shielded room in conjunction with a high-Tc SQUID based active compensation. Experimental results show that a noise level of pico-tesla in MCG profiles, which is necessary for clinical applications, may be achieved with the system. Moreover, stable and convenient operations of the system are demonstrated with simulating MCG measurements. 相似文献
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将心磁信号从干扰噪声中加以提取并有效地消除噪声干扰是心磁信号处理中尤为重要的环节 .从改进算法的角度出发,提出互补型自适应滤波器结构以实现心磁信号的消噪处理.该滤波器针对心磁这类非平稳信号进行设计,有效地解决了常规自适应滤波器应用于心磁信号处理时收敛速度和稳态误差的矛盾.通过仿真实验和心磁实验结果表明,该算法能有效地消除心磁信号的背景噪声和工频干扰噪声.同时该算法也可用于其他非平稳信号的消噪处理.
关键词:
自适应滤波
心磁图
最小均方误差 相似文献
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Considering the properties of slow change and quasi-periodicity of magnetocardiography (MCG) signal, we use an integrated technique of adaptive and low-pass filtering in dealing with two-channel MCG data measured by high Tc SQUIDs. The adaptive filter in the time domain is based on a noise feedback normalized least-mean-square (NLMS) algorithm, and the low-pass filter with a cutoff at 100Hz in the frequeucy domain characterized by Caussian functions is combined with a notch at the power line frequency. In this way, both relevant and irrelevant noises in original MCG data are largely eliminated. The method may also be useful for other slowly varying quasi-periodical signals. 相似文献
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A scanning superconducting quantum interfecrence device microscope for room temperature samples 下载免费PDF全文
We have constructed a scanning low-Tc superconducting quantum interference device (SQUID) microscope, in which the SQUID is mounted on the lower end of a copper rod and cooled to liquid helium temperature. There is a 65μm thick sapphire window under the SQUID. The sample at room temperature underneath the window can be scanned to produce magnetic images. The microscope has a spatial resolution of 100-150μm and a magnetic field sensitivity of 3-60pT/\sqrt{Hz} in a magnetically unshielded environment. We have used this scanning SQUID microscope to measure various room temperature samples. 相似文献
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在耐熔金属约瑟夫逊制备过程中,我们应用各种分析技术对Nb/AlOx-Al/Mb基本结构的质量作了检验;基于这些分析,从实验上了用直流磁控溅射制备该结构时的最佳参数。 相似文献