Project Info
Energy Loss Mechanisms in Superconducting Quantum Circuits
Serena Eley | serenaeley@mines.edu
Superconducting microwave resonators are micron-sized elements that are integral components in superconducting quantum circuits used for computing and for sensing. These resonators suffer from energy losses due to vortices (penetrated magnetic flux), two-level systems (an atom or ion tunneling between an asymmetric double well potentials), and quasiparticles (unpaired electrons). These energy loss mechanisms are the same ones that afflict superconducting qubits used in prototype quantum computers. Two-level systems (TLSs) are the biggest source of energy loss, but we don’t really know what they are on a microscopic level. That is, we model TLSs as an atom or ion that tunnels between an double well potential, but we don’t know what type of defects or disorder in the materials creates this double-well potential nor the moving degree of freedom (where this moving atom or ion is coming from and what it is). TLSs are problematic because, if the moving ion is charged, you can think of it as a dipole that interacts with electric fields (from currents) in the circuitry.
The project would involve fabricating micropatterned superconducting resonators of different superconducting materials in the Mines cleanroom and measuring the Q-factors (metric for energy loss; high Q means low energy loss) of the resonators in a dilution cryostat in Prof. Singh’s lab (T = 7 mK). The student will compare the Q values of resonators of different materials and try to correlate them with the microstructure or other material properties. This work will contribute to a larger research project involving identifying the microscopic origin of TLSs and developing a mitigation strategy.
More Information
Grand Engineering Challenge: Engineer the tools of scientific discovery
Student Preparation
Qualifications
Introductory Quantum Mechanics
Analog Circuits
Time Commitment
20 hours/month
Skills/Techniques Gained
Micro/nanofabrication
Low temperature magnetometry and transport measurements
A basic understanding of superconductivity
Mentoring Plan
Regular weekly group meetings
Assisting with equipment training
One-on-one meetings on an as-needed basis.