Kouwenhoven Lab
We study low-dimensional nano-scale semiconductor systems. Our research focuses on basic properties of these systems as well as on possible applications in quantum information processing and novel opto-electronic devices. We are part of the Quantum Transport Group at Delft University of Technology in the Netherlands.
Through nanofabrication we define nanoscale electronic and photonic devices with new quantum functionality. Those devices are measured at very low temperatures (close to absolute zero temperature). Our labs are high-tech in terms of nanofabrication, low-temperature setups and low-noise electronics. We hope that in the long term our fundamental studies will turn quantum mechanics into a new resource for technology.
Our current research efforts are mainly aimed towards artificial Kitaev chains defined in arrays of quantum dots coupled by superconductors. Majorana bound states are predicted to appear in these chains when the coupling parameters have been fine-tuned which could offer a pathway towards protected quantum computing. Very recent advances in materials and understanding of the physics of superconductor-semiconductor systems, such as control over singlet and triplet cooper pair splitting [1], has allowed the detection of Majorana signatures in arrays of two and three quantum dots [2,3].
A schematic of a 2-site Kitaev Chain [2]
An image of a 3-site Chain [3]
These achievements have opened the door to quantum information experiments with Majorana bound states. Examples of ongoing projects are:
Majorana parity qubit based on two-site Kitaev chains [4]
Coupling two chains with four Majorana states allows encoding a qubit into the parity of the two chains. Control over the couplings within and between the chains allows for universal qubit control.
Braiding with two-site Kitaev chains [5]
Majorana modes are predicted to have non-abelian statistics which can be demonstrated through “braiding”, i.e. coherently exchanging the Majoranas in space.
Qubit based on three-site Kitaev chains [6]
As three-site Kitaev chains are more robust to charge noise than two-site chains, a three-site qubit will likely have better coherence properties.
A SEM image of one of our latest devices, which can be used to implement a two-site parity qubit. [6]
[1] Wang, G., et al. “Singlet and Triplet Cooper Pair Splitting in Hybrid Superconducting Nanowires.” Nature, vol. 612, 2022, pp. 448–53, arXiv:2205.03458.
[2] Dvir, Tom, et al. “Realization of a Minimal Kitaev Chain in Coupled Quantum Dots.” Nature, vol. 614, no. 7948, 2023, pp. 445–450
[3] Bordin, Alberto, et al. “Signatures of Majorana Protection in a Three-Site Kitaev Chain.” arXiv, 29 Feb. 2024, arxiv.org/abs/2402.19382
[4] Pan, Haining, et al. “Rabi and Ramsey Oscillations of a Majorana Qubit in a Quantum Dot-Superconductor Array.” arXiv, 23 July 2024, arxiv.org/abs/2407.16750
[5] Miles, Sebastian, et al. “Braiding Majoranas in a Linear Quantum Dot-Superconductor Array: Mitigating the Errors from Coulomb Repulsion and Residual Tunneling.” arXiv, 27 Jan. 2025, arxiv.org/abs/2501.16056.
[6] Bordin, Alberto. Engineering the Kitaev Chain. Delft University of Technology, 2025
