Martin Leijnse

Research:

I am a theoretical condensed matter physicist primarily interested in nanoscale systems. On such small length scales, the physics is drastically different from what we know in our all-day life and is dominated by the laws of quantum mechanics. In my group we investigate different ways of taking advantage of quantum mechanics to design for example electronic components with desirable properties. Although all our research is theoretical, we collaborate closely with experimental groups both in Lund and internationally. Specific research topics include:

Superconducting proximity effect and Majorana states.

When a superconductor is tunnel coupled to for example a semiconductor, tunneling of Cooper pairs leads to proximity-induced superconductivity in the semiconductor. We are interested in how this can be used to engineer superconductors with new exciting properties, such as topological superconductors hosting so-called Majorana fermion excitations. We also study how Majoranas can best be used for quantum information processing. 

Quantum transport in nanostructures.

Using primarily quantum master equation approaches, we study nonequilibrium transport in strongly interacting nanostructures, such as quantum dots, nanowires, and single-molecule devices. One goal is to understand how quantum transport can be used to extract spectroscopic information about a nanoscale system. Another goal is to propose devices where a combination of interaction and quantum mechanical effects give rise to some desired functionality, such as spin-polarized currents, negative differential resistance, or rectification.

Quantum thermodynamics.

We investigate different ways of using the properties of nanoscale and quantum systems in different types of thermodynamic engines. One example is thermoelectric devices effect, which convert a heat gradient directly into an electric current or voltage, where quantum confinement and other nanoscale effects can enhance efficiency. We also investigate ways of directly using or taking advantage of quantum entanglement or coherence in thermodynamic engines.

Research group

• Morten Munk (postdoc, shared with Peter Samuelsson): Quantum technologies in solid state nanosystems.
• Rubén Seoane Souto (postdoc): Superconductor-semiconductor hybrid structures and Majorana bound states.
• Florinda Viñas Boström (postdoc): Electronic and quantum transport properties of heterostructured nanowires.
• Martin Josefsson (postdoc): Thermoelectrics and quantum thermodynamics in nanoscale systems.
• Athanasios Tsintzis (PhD student): Quantum dots and quantum rings in heterostructured nanowires.
• Simon Wozny (PhD student): Quantum transport and quantum thermodynamics.
• Walter Talarico (visiting PhD student): Transport in correlated open quantum systems.
• Jakob Westerberg (MSc student): Time-dependent transport in semiconductor nanowires.
• Calle Stenberg (MSc student): Tight binding simulations of semiconductor nanowires.

Co-supervisor for PhD students:

• Timo Kerremans (main supervisor Peter Samuelsson).
• Antti Ranni (main supervisor Ville Maisi).

Teaching:

I currently teach the courses Elektroniska material (Electronic materials) and a PhD level course on Theory of superconductivity.

Commissions of trust:

• Member of the Young Academy of Sweden.
  Young Academy of Sweden (new window)
• Coordinator for education within NanoLund.
  Education pages
• Faculty member of the Solid State Physics Division. 
  Solid State Physics page (new window)
• External faculty member of the Center for Quantum Devices, University of Copenhagen.
  Center for Quantum Devices (new window)