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Spotlight on Dr Sebastian Weidt

Previous Research

I always wanted to know how the world works and why it works the way it does while also being interested in the business world, so I thought I’d study physics with management studies.

I thought you only go to University once and it would be amazing to contribute towards knowledge, maybe I should do a PhD. Throughout my PhD I researched quantum computing because I knew it has the potential to change the way we live

After I completed my PhD, I secured a post doc position and have since been very fortunate to secure a permanent research position in the Ion Quantum Technology group headed by Prof. Hensinger.

Current Research

Together with some amazing people, we have managed to develop a new approach to quantum computing.

We want to achieve building a quantum computer to fill the gaps where no classical computer in the world could help you. Problems that a classical computer would take a million years to complete, a quantum computer would do in a couple of minutes. This is expected to change the world we live in.

Superposition and entanglement; that’s all you need for a quantum computer!
They’re really the two fundamental ingredients. There’s a huge research field out there trying to find the most suitable system to tame these two quantum concepts and we believe we have a very strong candidate

‘Superposition’ is a strange phenomenon in quantum physics that means things can be in two places at the same time.

That’s like getting in your car and being able to go forward and backwards at the same time. However, it’s only at the really small, atomic scale, that this quantum effect comes in. When you go down to the detail of how a classic computer is coded, it’s all ‘bits’ that are either 0s or 1s. In quantum computing we use quantum bits or qubits which in our case we encode in single atoms. Instead of only being either 0 or 1 qubits can be both 0 and 1 at the same time which makes for a very powerful tool.

‘Entanglement’ is where it gets really weird. Many people like to quote Einstein who called it ‘spooky’. Imagine it was possible to create entanglement between how two people are feeling and one person went to the moon and the other stayed here on earth. They would be connected in such a way that if you asked the person on earth how they are feeling, the answer would determine how the person on the moon is feeling. We create this type of connection between our qubits which provides for a very powerful interaction between all qubits in the quantum computer

We apply these two core quantum effects to trapped ions, which are charged atoms and each constitutes a single qubit. So we put a qubit into a superposition or entangle them using operations analogous to those used in a classical computer. Until now the standard way to do this very successfully has been by using laser beams applied to a few qubits. However, there are significant challenges when progressing from these proof of principle experiments with a handful of qubits, to operating millions of qubits required for a universal quantum computer. If you imagine every qubit needs a laser beam, how does one build and operate a system consisting of millions of laser beams and align each beam accurately on such small scales?

We’ve developed a completely new way of doing this, using microwaves and currents. Our approach only requires a handful of microwave fields instead of millions of laser beams to perform operations on millions or billions of qubits. Making use of well-developed and robust technology such as microwave technology which you, for example, find in your mobile phone together with only requiring a handful of fields makes us believe that we can really build a quantum computer now.

I believe our biggest achievement really has been changing the way one would think about building a quantum computer in a way that hopefully makes it a lot simpler to achieve. It is great to see people getting very excited about our approach and quantum computing in general.  We have also recently developed an engineering blue-print for how to build a large-scale quantum computer based on our new approach. We are now using this work to build a quantum computer demonstrator device here at Sussex and experimentally show that our approach will work on a very large scale.

Quantum Computing Lab at Sussex

The Future

I think my real aspiration is developing quantum technologies and bringing them into the commercial world. The quantum computer is often seen as the Holy Grail but there are other amazing quantum technologies which will impact us on a much shorter timescale. We’re building a portable quantum sensor (magnetometer) right now, a device which can detect anomalies in structures under the ground. It could also be used for example within the healthcare, environmental, geological and security sector.

Just like at the beginning no one knew exactly what a classic computer would be useful for, we don’t yet have a complete picture of where the applications of quantum computing lie.
We’re heavily engaging with industry to guide our development, asking what computations do even your fastest classical computers struggle with? We’re really keen to tailor our development to what the world needs to ensure the biggest impact. We’re trying to make everyone realise, this isn’t just about code breaking, the quantum computer will do a lot more and it is extremely exciting to continuously uncover more applications.

This will be big, we’re at this point now where it isn’t a question of can this really be done, it’s more a question of when?


Sebastian’s work is part of the UK National Quantum Technology Hub on Sensors and Metrology and the UK National Quantum Technology Hub on Networked Quantum Information Technologies.

Sebastian's Links


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By: Kirsty Bridger
Last updated: Friday, 11 November 2016