Scholarlink

<p>Cryogenic filtering and attenuation play a crucial role in the control and readout of superconducting qubits, ensuring that unwanted noise does not degrade qubit coherence. These devices typically operate in the microwave C band (4–8&#xa0;GHz) and use attenuators (input) and circulators/isolators (output) to control in-band noise, while reflective filters are used to reject out-of-band noise. However, these devices tend to become transparent to terahertz and infrared radiation. Such high-frequency radiation reaching the qubit destroys superconductivity and induces dissipation, degrading the coherence properties of these devices. Magnetically loaded epoxy (like Eccosorb<InlineEquation ID="IEq1"><EquationSource Format="TEX">\(^\mathrm{{TM}}\)</EquationSource></InlineEquation>) has been widely used as a dielectric to construct filters that absorb high-frequency radiation while minimizing loss in the operating band. Here, we demonstrate the construction and characterization of absorptive filters with variable in-band attenuation by combining Eccosorb<InlineEquation ID="IEq2"><EquationSource Format="TEX">\(^\mathrm{{TM}}\)</EquationSource></InlineEquation> or iron powder mixed with Stycast in different ratios. We show that such filters can be made with sufficiently large in-band attenuation to replace the usual thin-film resistor-based attenuators and simplify cryogenic wiring by combining attenuation and IR filtering in a single device. We characterize the microwave performance at room temperature and at dilution fridge temperatures for devices with insertion losses ranging from 1&#xa0;dB to 20&#xa0;dB at 7&#xa0;GHz. In a separate set of experiments, we also test the materials’ absorption capabilities at terahertz frequencies up to 450&#xa0;GHz. Finally, we demonstrate high coherence in a 3D superconducting qubit (<InlineEquation ID="IEq3"><EquationSource Format="TEX">\(T_1, T_2^E \approx 100~\mu s\)</EquationSource></InlineEquation>) using these filters and attenuators, thereby confirming their efficacy.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Magnetically loaded dielectric based absorptive filters and attenuators with tunable attenuation for superconducting quantum circuits

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年7月31日

查看全文
  • Srijita Das,
  • Madhavi Chand,
  • Samuel John,
  • Snehal Haldankar,
  • Meghan P. Patankar,
  • Shriganesh Prabhu,
  • R. Vijay

摘要

Cryogenic filtering and attenuation play a crucial role in the control and readout of superconducting qubits, ensuring that unwanted noise does not degrade qubit coherence. These devices typically operate in the microwave C band (4–8 GHz) and use attenuators (input) and circulators/isolators (output) to control in-band noise, while reflective filters are used to reject out-of-band noise. However, these devices tend to become transparent to terahertz and infrared radiation. Such high-frequency radiation reaching the qubit destroys superconductivity and induces dissipation, degrading the coherence properties of these devices. Magnetically loaded epoxy (like Eccosorb\(^\mathrm{{TM}}\)) has been widely used as a dielectric to construct filters that absorb high-frequency radiation while minimizing loss in the operating band. Here, we demonstrate the construction and characterization of absorptive filters with variable in-band attenuation by combining Eccosorb\(^\mathrm{{TM}}\) or iron powder mixed with Stycast in different ratios. We show that such filters can be made with sufficiently large in-band attenuation to replace the usual thin-film resistor-based attenuators and simplify cryogenic wiring by combining attenuation and IR filtering in a single device. We characterize the microwave performance at room temperature and at dilution fridge temperatures for devices with insertion losses ranging from 1 dB to 20 dB at 7 GHz. In a separate set of experiments, we also test the materials’ absorption capabilities at terahertz frequencies up to 450 GHz. Finally, we demonstrate high coherence in a 3D superconducting qubit (\(T_1, T_2^E \approx 100~\mu s\)) using these filters and attenuators, thereby confirming their efficacy.