A magnetic field insensitive graphene transmon qubit

A magnetic field insensitive graphene transmon qubit

van der Enden, Kian (TU Delft Applied Sciences)

Kouwenhoven, Leo (mentor)
Kroll, James (graduation committee)

Delft University of Technology

Applied Physics

2017-08-18

Majorana zero modes have been proposed as building blocks of intrinsically fault-tolerant quantum computers. Currently, externally applied magnetic fields are necessary to induce Majorana zero modes in carefully engineered systems. Topological qubit state readout is realized by parity sensing of Majorana islands. However, fast and high fidelity conventional cQED parity readout is incompatible with the magnetic fields needed for Majorana physics. In this thesis, magnetic field insensitive microwave CPW resonators with artificial Abrikosov vortex pinning sites have tested and implemented in a graphene based transmon qubit. It has been shown that these artificial pinning sites reliably trap vortices and are able to retain their zero field Q_i ~ 10⁵ up to perpendicular fields of 35 mT. By application of these resonators, we have described the successful continuous wave qubit spectroscopy of a graphene transmon qubit at B_|| = 1 T with a minimal linewidth of 166 MHz and demonstrated manipulation of the qubit frequency between 3.2-7 GHz with electric field. This is the first ever measured superconducting qubit that shows these properties at a magnetic field of 1 T.

topological
quantum computing
graphene
superconducting
majorana
measurement
qubit
superconducting qubit
qubit spectroscopy
microwave resonator
coplanar waveguide
magnetic field
cQED
circuit quantum electrodynamics
vortex pinning
Abrikosov
parity
readout
transmon
superconducting transmon
finite element analysis
simulation
CST
time domain

http://resolver.tudelft.nl/uuid:6cca6326-7933-4595-b0da-6e89f83fc655

Student theses

master thesis

© 2017 Kian van der Enden