I work as a quantum innovation officer at the University of Amsterdam and QuSoft. I accelarate the development of valuable quantum technology by connecting Netherlands-based companies to academic research. As one of the main valorization activities, we build the Quantum.Amsterdam innovation hub, for which I am the community manager.
I am also involved in scientific research on quantum computers. In my work, we find input signals (like electric waves or laser pulses) that make a quantum computers perform a desired operation on quantum data. Examples are shuttling information from one part of the computer to another, or executing the quantum-version of certain logical gates like AND and OR. READ MORE >
Masterclass: Introduction to Quantum Technology
Update to Professional's Guide to Quantum Technology
Professional's Guide to Quantum Technology
Available MSc student project: A Quantum Benchmarking tool
Masterclass for High Shool students in January/February
Only available in Dutch:
Are you a smart high-school student in 5-6 VWO, and would you like to learn about the cutting edge of Quantum Computers and Quantum Field Theory? (Or do you know one?) During this 3-day masterclass, you will take lectures at the University of Amsterdam and learn all about these fascinating topics:
Quantum Quest 2021 has started!
The Quantum Quest is a free online webclass for students in the last years of high school (~16-20 years old). During a 5-week program, we dive into the mathematics behind quantum computing, going through probabilistic bits, quantum bits, unitary operations, and elementary algorithms and protocols (like Teleportation and Grover's search). To make the material sufficiently accessible, we omit complex numbers and work only with reals (and surprisingly, quantum computers still work fine!).
The course is extremely challenging and aiming at the best-of-class students. This year, we opened up submissions to anyone in the world, and have a very international audience (note the peak in Africa, especially Ghana, thanks to our collaboration with AIMS):
Signups for 2021 have closed... but if you're interested in participating:
More in-depth testing of N-qubit gates
Juan Diego Arias Espinoza performed an extensive numerical analysis that our proposed method to perform an important gate, the Toffoli gate, performs very well on Trapped Ion computers. However, some clever tricks were needed to get the fidelities up to competitive levels. The result was recently published in PRA in the paper "High-fidelity method for a single-step N -bit Toffoli gate in trapped ions".
Efficient circuits for Trapped Ion quantum computers
We find a striking connection between the physics of quantum computers that use trapped ions, and the emerging field of quantum signal processing. This allows us to perform difficult quantum gates in less steps, relying only on the most simple entangling operation a trapped ion computer can perform.
(Update July 2020) This result is now published as follows:
Koen Groenland, Freek Witteveen, Kareljan Schoutens, Rene Gerritsma, Signal processing techniques for efficient compilation of controlled rotations in trapped ions, New Journal of Physics, Volume 22 (2020)
Difficult quantum gates can be performed in a single step
Together with Stig Rasmussen and Nikolaj Zinner from Aarhus University, we find that the notoriously hard Toffoli quantum gate can be performed using a surprisingly simple protocol. We require an all-to-all Ising type interaction between the qubits, and a resonant field on a single special qubit. After throwing away the special qubit, a Toffoli occurred on the remaining qubits.
(Update Februari 2020) This result is now published as:
Popular state transfer protocols now work in more cases
Certain experimental protocols, named with acronyms STIRAP or CTAP, turn out to work on many more systems than was previously known. We find that they naturally generalize to bipartite graphs.
KG, Carla Groenalnd, Reinier Kramer, Adiabatic transfer of amplitude using STIRAP-like protocols generalizes to many bipartite graphs, Journal of Mathematical Physics 61, 072201 (2020); arXiv:1904.09915
Transferring a quantum state over a network of coupled spins
With the advent of advanced quantum information processing, it is of increasing importance to transport quantum information over a physical medium (think of a wire, or a network of wires). We consider the case where the information is encoded in a spin degree of freedom (think of an electron whose "rotation axis" can point either up or down), and the medium is made up of spins that are all pinned in place.
It turns out that the repulsive forces between the spins can be used to delocalize the information over the whole network, and then localize it again at some other place. This was known for mediums that form a perfect line. I generalize this to more general configurations, finding that information can be sent over many networks that look like a bipartite graph.
My article is planned for publication in SciPost Physics (DOI: 10.21468/scipostphys.6.1.011)
Many-body strategies for multi-qubit gates
Quantum computers, just like their classical counterparts, may use a universal gate set consisting of local gates, in order to approximate any possible operation on it's qubits. Typically, one chooses a two-qubit gate such as the CNOT together with a set of single-qubit gates.
However, we asked ourselves the question: If N qubits are coupled by some interaction of our choice, can we construct interesting gates that act on all qubits at the same time?
For this to work, we look at the so-called Krawtchouk chain, which is special because all of it's eigenvalues are integer numbers. Because this system is well understood, we can apply condensed-matter many-body techniques, resulting in two surprising new contributions:
The eigengate, which maps computational states into eigenstates of the coupling Hamiltonian.
Resonant driving, which, together with knowledge of the simple spectrum, allows us to select precisely 2 our of 2^N (and no more!) to undergo a transition.
Our article was recently published in PRA (https://journals.aps.org/pra/abstract/10.1103/PhysRevA.97.042321). Find the version without paywall at ArXiv or my GDrive.