Majorana fermions in superconductors are the subgap quasiparticle excitations that are their own antiparticles.

This thesis is devoted to an in-depth examination of the various effects of disorder in the cuprate high-temperature superconductors.

In this thesis we use Josephson and noise scanning tunneling microscopy for the study of conventional, unconventional (iron-based) and disordered superconductors. On the one hand, Josephson scanning tunneling microscopy allows us to directly visualize the superfluid density with high spatial resolut…

The thesis mainly contributes to the characterization of Majorana fermions as they appear in the Condensed Matter context.

Leiden physicist Milan Allan and his group have discovered an apparent paradox within a material that has zero electrical resistance. They measured trapped charges, while charges should in theory keep flowing in the absence of resistance. The discovery could provide a missing piece of one of the big…

High-temperature superconductivity is one of the big mysteries in physics. Milan Allan’s research group used a Josephson Scanning Tunneling Microscope to image spatial variations of superconducting particles for the first time, and published about it in the journal Nature.

In their quest for materials that conduct electricity without resistance at moderate temperatures, scientists usually work on their chemical make-up. Now Leiden physicists have come up with a radically new approach: pinching holes in a periodic pattern. Publication in SciPost.

Promotor: T. H. Oosterkamp

We don’t understand how some materials become superconducting at relatively high temperatures. Leiden physicists have now found a surprising connection with auxiliary black holes. It enables us to use our knowledge of black holes on the mystery of high-temperature superconductivity. Publication in Nature…

Promotor: Prof.dr. C.W.J. Beenakker

Promotor: C.W.J. Beenakker, Co-promotor: M.T. Wimmer

In unconventional high temperature superconductors, supercurrent vortices are known to spoil the Landau levels. In this thesis the emergence of Landau levels is studied in different types of superconductors: Weyl superconductors, and the Fu-Kane heterostructure.

Promotor: C.W.J. Beenakker, Co-Promotor: A.R. Akhmerov

We are a dynamic research group at the Leiden Institute of Physics. Our aim is to explore and understand quantum materials, including strange metals, high-temperature superconductors, and quantum critical electron matter.

Promotor: C. W. J. Beenakker, Yu. V. Nazarov, Co-promotor: J. Tworzydlo

If computers work on superconducting current, they won’t consume any energy. Leiden physicists have now gained control over a new type of superconducting memory elements. Publication in Nature Communications.

What is the connection between materials with weak and strong gravitational interactions?

Promotores: Prof.dr. J. Zaanen & Prof.dr. K.E. Schalm

This thesis presents the results of a study on the interfaces of insulating oxides with and without the insertion of a magnetic layer.

PhD Defence

PhD Defence

The focus of our theoretical physics research is the nature of macroscopic matter that is in one or the other way still in the grip of quantum physics.

In my group (the Aarts lab) we combine or structure materials, mostly in thin film form, in such a way that the hybrid has different and novel properties or functionalities.

Materials with strongly correlated electrons show some of the most mysterious and exotic phases of quantum matter, such as unconventional superconductivity, quantum criticality and strange metal phase.

Promotor: K.E. Schalm, Co-promotor: S.S. Lee

With the help of quantum mechanics, digital quantum hardware may be able to tackle some of the problems that are too difficult for ordinary computers. But despite these expectations and the ongoing effort of the research community, reliable quantum computers are not yet realized in a lab setting.

PhD Defence

Making the most vibration-free, cryogenic scanning tunneling microscope in the world. A bold mission, but one that PhD candidate Irene Battisti successfully executed together with the Fine Mechanical Department. The new microscope might shed light on how unconventional superconductivity works. PhD Defence…

Unconventional superconductors form one of the big mysteries in physics. Among them is strontium ruthenate, which stands out as a controversial superconductor. During his PhD, Leiden physicist Kaveh Lahabi has provided new insights into the nature of superconductivity in this material, leading to a…

Irene Battisti is the discoverer of the year 2019. The physicist won the C.J. Kok Public Award for her research into microscopy and superconductors.

The behaviour of strongly correlated electron systems, such as high-temperature superconductors, defies explanation in the language of ordinary quantum theory. A seemingly unrelated area of physics, string theory, might give physicists a better understanding of the weird behaviour of these kinds of…

Physicists Carlo Beenakker and Jan Aarts have been elected Fellows of the American Physical Society. Carlo Beenakker: 'People acknowledge your contribution, that is just very good to hear.'

The European Research Commission (ERC) has awarded Advanced Grants to two Leiden researchers. Joke Meijer will be researching the effect of the biological clock on our health and Carlo Beenakker will be looking for Majorana fermions in superconductors.

For the first time, physicists have visualized the ‘melting’ of electrons inside a special class of insulators. It allows electrons to move freely and turns the insulator into a metal and possibly later into a superconductor. Publication in Nature Physics.

Koen Bastiaans and his colleagues discovered a new quantum liquid unlike anything ever seen. They did it by using a technique that can be compared to listening to the sound of raindrops falling on a roof. Publication in Science 29 October.

The Joan Van der Waals colloquium is an ongoing bi-weekly lecture series.

Majorana particles have been getting bad publicity: a claimed discovery in ultracold nanowires had to be retracted. Now Leiden physicists open up a new door to detecting Majoranas in a different experimental system, the Fu-Kane heterostructure, they announce in Physical Review Letters.

An overview of awards and prizes granted to our staff and students in 2019, as well as special appointments and royal distinctions.

Scientists at TU Delft and Leiden University have observed supercurrents in graphene that bounce back and forth between the edges of the graphene without scattering along the way.

Knots come in all shapes and sizes: mariners and scouts can vouch for this. Sjabbo Schaveling will obtain his PhD on 1 September for a mathematical method to distinguish between all these knots. ‘I flatten them to a pretzel.’

Stack two layers of graphene, twisted at slightly different angles to each other, and the material spontaneously becomes a superconductor. Science still can't explain how something so magical can happen, but physicists use special equipment to reveal what is taking place under the surface.

NWO has granted Jan Aarts en Vadim Cheianov a Physics Projectruimte, a granting instrument for small-scale projects that propose innovative fundamental physics research that has a scientific, industrial or social urgency.

Physics professor Jan Aarts starts a collaboration with chip manufacturer Intel to perform fundamental research in low-power, cryogenic computing.

Jan Aarts, Leiden professor in experimental physics, has been appointed Ridder in de Orde van de Nederlandse Leeuw. He received the royal distinction from the mayor of Leiden Henri Lenferink in the Hooglandse Kerk.

The Leiden Institute of Physics has been awarded three out of twelve available grants from the FOM Projectruimte. Principal Investigators Milan Allan, Stefan Semrau and Carlo Beenakker all receive around 400,000 euro for their research.

On Friday April 6th, Leiden University organizes its biannual try-out day. We pay a visit to Physics and Astronomy, which saw their student numbers almost quadruple over the past decade.

Leiden physicists and international colleagues from Geneva and Barcelona have confirmed the mechanism that makes magic-angle graphene superconducting. This is a key step in elucidating high-temperature superconductivity, a decades-old mystery central to physics, which may lead to technological break…

Physicist Milan Allan will build an instrument that will bring superconductivity research further. He has been awarded an ERC Consolidator Grant of 2 million euros over the next five years. With his PairNoise programme he aims to detect paired electrons as they occur just above the temperature at which…

Bernard van Heck has won the Christiaan Huygens Prize 2016 for his Leiden PhD research on electrical circuits for quantum computers. On behalf of the KNAW, the Dutch minister of Education, Culture and Science awards this prize annually to a researcher who has made an innovative contribution to scien…