Grégory Strübi
ContactDepartment of PhysicsUniversity of Basel Klingelbergstrasse 82 CH4056 Basel, Switzerland

Short CV
Since April 2010  PhD student under the supervision of Christoph Bruder 
2010  Master of Physics at the EPFL 
Publications
Show all abstracts.1.  Point contacts and localization in generic helical liquids 
Christoph P. Orth, Grégory Strübi, and Thomas L. Schmidt. arXiv:1305.1875
We consider two helical liquids on opposite edges of a narrow twodimensional
topological insulator, which are connected by one or several local tunnel
junctions. In the presence of spatially inhomogeneous Rashba spinorbit
coupling, the spin textures of the helical states on opposite edges are
different. We demonstrate that this has a strong impact on the electron
transport between the edges. In particular, in the case of many random tunnel
contacts, the localization length depends strongly on the spin textures of the
edge states.
 
2.  Measuring Ultrasmall Time Delays of Light by Joint Weak Measurements 
Grégory Strübi (University of Basel) and Christoph Bruder (University of Basel). Phys. Rev. Lett. 110, 083605 (2013).; arXiv:1301.5846.
We propose to use weak measurements away from the weakvalue amplification regime to carry out precision measurements of time delays of light. Our scheme is robust to several sources of noise that are shown to only limit the relative precision of the measurement. Thus, they do not set a limit on the smallest measurable phase shift, contrary to standard interferometry and weakvaluebased measurement techniques. Our idea is not restricted to phaseshift measurements and could be used to measure other small effects using a similar protocol.
 
3.  Interferometric and Noise Signatures of Majorana Fermion Edge States in Transport Experiments 
Grégory Strübi (University of Basel), Wolfgang Belzig (UniversitĂ¤t Konstanz), MahnSoo Choi (Korea University, Seoul), and Christoph Bruder (University of Basel). Phys. Rev. Lett. 107, 136403 (2011).; arXiv:1109.0393.
Domain walls between superconducting and magnetic regions placed on top of a topological insulator support transport channels for Majorana fermions. We propose to study noise correlations in a Hanbury Brownâ€“Twiss type interferometer and find three signatures of the Majorana nature of the channels. First, the average charge current in the outgoing leads vanishes. Furthermore, we predict an anomalously large shot noise in the output ports for a vanishing average current signal. Adding a quantum point contact to the setup, we find a surprising absence of partition noise which can be traced back to the Majorana nature of the carriers.
 
4.  Vison excitations in nearcritical quantum dimer models 
Grégory Strübi and Dmitri A. Ivanov. EPL 94, 57003 (2011); arXiv:1009.1040.
We study vison excitations in a quantum dimer model interpolating between the
RokhsarKivelson models on the square and triangular lattices. In the
squarelattice case, the model is known to be critical and characterized by
U(1) topological quantum numbers. Introducing diagonal dimers brings the model
to a Z_2 resonatingvalencebond phase. We study variationally the emergence of
vison excitations at low concentration of diagonal dimers, close to the
critical point. We find that, in this regime, vison excitations are large in
size and their structure resembles vortices in typeII superconductors.
