Elizaveta I. Malevannaya

An engineering guide to superconducting quantum circuit shielding

  1. Elizaveta I. Malevannaya,
  2. Viktor I. Polozov,
  3. Anton I. Ivanov,
  4. Aleksei R. Matanin,
  5. Nikita S. Smirnov,
  6. Vladimir V. Echeistov,
  7. Dmitry O. Moskalev,
  8. Dmitry A. Mikhalin,
  9. Denis E. Shirokov,
  10. Yuri V. Panfilov,
  11. Ilya A. Ryzhikov,
  12. Aleksander V. Andriyash,
  13. and Ilya A. Rodionov
In this review, we provide a practical guide on protection of superconducting quantum circuits from broadband electromagnetic and infrared-radiation noise by using cryogenic shielding
and filtering of microwave lines. Recently, superconducting multi-qubit processors demonstrated quantum supremacy and quantum error correction below the surface code threshold. However, the decoherence-induced loss of quantum information still remains a challenge for more than 100 qubit quantum computing. Here, we review the key aspects of superconducting quantum circuits protection from stray electromagnetic fields and infrared radiation, namely, multilayer shielding design, materials, filtering of the fridge lines and attenuation, cryogenic setup configurations, and methods for shielding efficiency evaluation developed over the last 10 years. In summary, we make recommendations for creation of an efficient and compact shielding system as well as microwave filtering for a large-scale superconducting quantum systems.
arxiv pdf

Robust cryogenic matched low-pass coaxial filters for quantum computing applications

  1. Andrey A. Samoylov,
  2. Anton I. Ivanov,
  3. Vladimir V. Echeistov,
  4. Elizaveta I. Malevannaya,
  5. Aleksei R. Matanin,
  6. Nikita S. Smirnov,
  7. Victor I. Polozov,
  8. and Ilya A. Rodionov
Electromagnetic noise is one of the key external factors decreasing superconducting qubits coherence. Matched coaxial filters can prevent microwave and IR photons negative influence
on superconducting quantum circuits. Here, we report on design and fabrication route of matched low-pass coaxial filters for noise-sensitive measurements at milliKelvin temperatures. A robust transmission coefficient with designed linear absorption (-1dB/GHz) and ultralow reflection losses less than -20 dB up to 20 GHz is achieved. We present a mathematical model for evaluating and predicting filters transmission parameters depending on their dimensions. It is experimentally approved on two filters prototypes different lengths with compound of Cu powder and Stycast commercial resin demonstrating excellent matching. The presented design and assembly route are universal for various compounds and provide high repeatability of geometrical and microwave characteristics. Finally, we demonstrate three filters with almost equal reflection and transmission characteristics in the range from 0 to 20 GHz, which is quite useful to control multiple channel superconducting quantum circuits.
arxiv pdf