My research interests include topological states of matter, exotic superconductivity, properties of vortices, quantum Hall effects, cold atoms, Majorana fermions, fractional statistics; and the harnessing of these ideas towards topological quantum computation.
I am currently seeking MSc and PhD students to fill several positions.
There is also a post-doctoral position available (see my group page).
Microwave transitions as a signature of coherent parity mixing effects in the Majorana-Transmon qubit
Coupling Majorana fermion excitations to coherent external fields is an important stage towards their manipulation and detection. We analyse the charge and transmon regimes of a topological nano-wire embedded within a Cooper-Pair-Box, where the superconducting phase difference is coupled to the zero energy parity states that arise from Majorana quasi-particles. We show that at special gate bias points, the photon-qubit coupling can be switched off via quantum interference, and in other points it is exponentially dependent on the control parameter EJ/EC . As well as a probe for topological-superconductor excitations, we propose that this type of device could be used to realise a tunable high coherence four-level system in the superconducting circuits architecture.
On the effective theory of vortices in two-dimensional spinless chiral p-wave superfluid
We propose a U(1)xZ2 effective gauge theory for vortices in a px+ipy superfluid in two dimensions. The combined gauge transformation binds U(1) and Z2 defects so that the total transformation remains single-valued and manifestly preserves the particle-hole symmetry of the action. The Z2 gauge field introduces a complete Chern-Simmons term in addiction to a partial one associated with the U(1) gauge fiel. The theory reproduces the known physics vortex dynamics such as a Magnus force proportional to the superfluid density. It also predicts a universal Abelian phase, exp(iπ/8) upon the exchange of two vortices, modified by non-universal corrections due to the partial Chern-Simon term that are screened in a charged superfluid.
Majorana fermion zero modes carried by solitons and detection of non-abelian statistics
Josephson vortices are phase solitons living in thin insulators separating two superconductors. For topological superconductors, we have recently shown that each soliton carries a single localized Majorana zero mode bound to the soliton. The presence of the Majorana mode renders the quantum exchange statistics of two solitons non-abelian. In order to allow detection of soliton statistics, we propose an interferometer geometry. The presence of Majorana modes is reflected in the interference pattern of the soliton beam.
- Topological materials
- Exotic quasi-particles
- Applications of quantum field theory to solid state