Designing 3D Cavity For Photon Number Cooling Using Quantum Circuit Refrigerator

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Perustieteiden korkeakoulu | Bachelor's thesis
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Date

2024-04-26

Department

Major/Subject

Quantum Technology

Mcode

SCI3103

Degree programme

Aalto Bachelor’s Programme in Science and Technology

Language

en

Pages

40+1

Series

Abstract

Qubits are the fundamental components of quantum computers, and 3D cavity resonators are often used to study qubits in low-noise environments. However, to achieve even lower noises, quantum circuit refrigerators (QCRs) can be used to reduce photon numbers in qubits and resonators. In this thesis, a 3D cavity resonator model is proposed for coupling to QCRs, and then the model’s performance is characterised using two physical 3D cavities, made of aluminium and copper, respectively. The performance of the 3D cavity resonator was quantified using transmission and reflection measurements from a vector network analyser (VNA), which were used to estimate the resonant frequency and quality factor. The measurements were conducted at room temperature and cryogenic temperatures, using a cryogen-free dilution refrigerator. Based on the current results, the 3D cavity resonator significantly underperforms the simulations, with the 3D cavities reaching quality factors of 67 000 and 12 000, respectively.

Description

Supervisor

Raasakka, Matti

Thesis advisor

Nakamura, Shuji

Keywords

quantum circuit refrigerators, 3D cavities, superconducting devices, thermodynamics

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https://urn.fi/URN:NBN:fi:aalto-202406184542

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[kand] Perustieteiden korkeakoulu / SCI