Miniaturized high-energy radiation drain filters for quantum computing applications
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Wireless, photonics and space engineering (MPWPS), MSc
Publicerad
2023
Författare
Andersson, Linus
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Quantum Processing Units (QPUs) using superconducting qubits are known for
their sensitivity to various types of radiation and many different aspects are being
worked on in order to increase their resilience against noise. Superconducting qubits
are especially sensitive frequencies with energy exceeding twice the superconducting
energy gap of the superconductor. Above this frequency, Copper-pairs start to break,
which partially disrupts superconductivity and degrades the performance of the
QPU. In order to tackle this problem, a new type of low pass filtering technique called
High Energy Radiation Drain (HERD) has been developed at at Chalmers University
of Technology. Unlike previously employed filters relying on absorptive materials
and resonant circuits to block high-frequency photons, this novel filtering technique
overcomes the trade-off between low losses in the passband and high attenuation
in the stopband. However, the filter is relatively large compared other filtering
techniques, which makes it less suitable for high qubit density systems. In this thesis,
we focus on the miniaturization of the HERD filtering technology and present two
devices which have a reduced size of 32-57% and 47% respectively compared to their
predecessor. The first device, implemented in printed circuit board technology, is
manufactured and characterized with a resulting insertion loss of more than 40 dB
above 80 GHz and an insertion loss of less than 0.29 dB below 8 GHz, measured at
77 K. The results show good agreement between measurements and simulations. In
addition, a software is developed for performing eigenmode field decomposition of
the filtering structure, which is used to better understand how the field couples to
the filtering structure inside the prototype. The insights obtained from simulations
and the field decomposition is then used to design the second device, a miniaturized
coaxial HERD filter. The results shows that the HERD filtering technique can be
made suitable for high qubit density systems where further miniaturization beyond
this thesis should be possible.
Beskrivning
Ämne/nyckelord
quantum computing, quasiparticles, filter design, infrared radiation, HERD filter, simulation and modelling, mode decomposition, filter optimization