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dScience Lunch Seminar: Designing Gates for Quantum Computing with Electrons on Liquid Helium

Welcome to this week's lunch seminar in the dScience lounge with Oskar Leinonen, PhD Candidate at the Department of Physics. He will talk about designing fast, high-fidelity two-qubit gates – the fundamental building blocks of quantum computing – using electrons on superfluid helium, a promising new platform that could surpass existing technologies in coherence and scalability.

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Presentation

Just as a classical computer processes information through logic gates — simple operations like AND, OR, and NOT that manipulate bits of 0s and 1s — a quantum computer relies on quantum gates to manipulate quantum bits, or qubits. Unlike classical bits, qubits can exist in a superposition of 0 and 1 simultaneously, and two qubits can become entangled, meaning the state of one is intrinsically linked to the other. This entanglement is what gives quantum computers their extraordinary computational power, and it is created and controlled by two-qubit gates, making them an essential building block of any quantum computer. In this talk, we present our recent work on designing such two-qubit gates for a novel and promising platform: electrons trapped on the surface of superfluid helium.

While superconducting circuits and trapped ions are currently the leading platforms for quantum computing, electrons on superfluid helium have recently emerged as a highly promising contender. The pristine helium layer protects the electrons from environmental noise, allowing either their spin or motional states to serve as exceptionally coherent qubits. By applying numerical methods from quantum many-body physics, we demonstrate that fast, high-fidelity two-qubit gates are achievable — positioning this unique system as a compelling candidate in the rapidly evolving landscape of quantum computing hardware.

The talk is based on the two following publications:

https://doi.org/10.1103/kys2-kfdk
https://doi.org/10.1103/PRXQuantum.5.030324

Speaker

Oskar Leinonen is a CompSci Phd Candidate at the Department of Physics at the University of Oslo. He holds a bachelor's degree in Engineering Physics and a master's degree in Applied Physics from Chalmers University of Technology in Gothenburg, where his thesis focused on the Variational Quantum Eigensolver for quantum chemistry applications. His main research interests are within quantum engineering, and for his PhD, he uses methods from quantum chemistry to study quantum dot systems suitable for quantum computing.

Program

11:30?– Doors open and lunch is served

12:00?– "Designing Gates for Quantum Computing with Electrons on Liquid Helium" by Oskar Leinonen (PhD Candidate, Condensed Matter Physics, Department of Physics)

This event is open for all students, PhD candidates, postdocs, and everyone else who is interested in the topic. No registration needed.

About the seminar series

Once a month, dScience will invite you to join us for lunch and professional talks?at the Science Library. In addition to these, we will serve lunch in our lounge in Kristine Bonnevies house every Thursday. Due to limited space (40 people), this will be first come, first served.?See how to find us here.

Our lounge can also be booked by?PhDs and Postdocs on a regular basis, whether it is for a meeting or just to hang out – we have fresh coffee all day long!

Lounge Calendar

Tags: dscience, postdoc, phd, lunch seminar
Published Nov. 27, 2025 2:52 PM - Last modified Mar. 27, 2026 3:49 PM