A nightly physics adventure


” WA R N I N G : 5 FAU LT S F O U N D ! “

by Niels Bultink

It was around 1:00 AM on a cold winter night in 2019 when I stepped out of a bar in the historic center of Delft. Time to go home, after celebrating Suzanne van Dam’s successful PhD defense. Evenings like these remind me why science is such a great endeavour. People might be working long hours to reach only tiny steps. But there is a team of people around you that understands the struggle. And, when those tiny steps lead to a big one, or occasionally even a breakthrough, celebration comes with all sorts of weird traditions. In short, it was an evening with a warm QuTech family feeling. For me personally it was also a nice change of scenery. Over the months prior, I had been working intensely on the final experiment of this thesis. In particular this week, I was finetuning day-in day-out to hunt for data sets that were fit for publication. Although the efforts of many had been finally coming together for quite some time: from design, to fabrication, to the integration of the setup; it is this final stage of an experiment that can make or break years of struggle for the whole team.
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Quarantine puzzle


The days get sunnier, yet the working from home continues. Some labs over the world are closed. At QuTech we have the luck that the labs stayed open, although the people in it disappeared. Monitoring measurements remotely and struggling with simulations is, also at QuTech, the new standard. With, of course, the now very well-known background noise of the video calls; people who are still on mute while talking, interesting background sounds and the frequency with which you can, or can’t hear someone with a failing internet connection (fun fact: the QuTech communications team even made a bingo card for everyone, containing the most-heard sentences in quantum video calls). The most interesting things we had so far were someone trying to fix his finances and stocks during a group meeting (and wasn’t muted), someone’s child breaking into a group meeting and someone’s pet chicken overtaking a whole meeting with its noise.

Yet more and more, we’re getting used to it. And a new normal requires new ways of keeping in touch and having fun together (one of the things I like of the video calls is that you get a sneak peak of someone’s home). That’s why the QuTech blog team organised a pub quiz for QuTech last Friday. It was a great success! The teams were competitive and we had a lot of fun with distributing the bonus points for best outfit and best background image. Of course, we don’t want to withheld you, therefore we made a puzzle out of the bonus questions of the quiz for you to think about during this long weekend.

In this puzzle you see nine tiles. Each tile cryptically describes a word that has something to do with quantum computers. You can fill in your answers in the answer card below (which also tells you how many letters an answer should have). If you fill it out correctly, you can read another word in the yellow tiles. A small note, a word like T2 would be spelled T-two and thus would occupy 5 tiles. Enjoy and good luck! The answers will be added to this post next week.

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Fabricating a superconducting quantum processor in a cleanroom


by Christos Zachariadis

Nowadays, quantum computers promise to be a revolutionary technology. As a result, quantum computing has become one of the hottest areas of research in the last decade. A lot of effort has been made on all layers of this new computer stack; from the creation of quantum algorithms to the development of hardware for devices. Lately, the bottleneck of the latter one starts to become more troublesome. Fabricating a growing number of qubits is increasingly difficult and samples are hard to reproduce on a large scale. In this blogpost, we’ll discuss the origins and the difficulties of fabricating a superconducting quantum processor. Continue reading Fabricating a superconducting quantum processor in a cleanroom

A word from an editor emeritus and new blog team members!


With QuTech expanding from a quantum transport research group to a large institute focusing on quantum computers, the number of people walking around in the hallways expands. It makes you almost forget that there are also people leaving. But as the seasons go by, PhD students at QuTech come and go. It gives QuTech its characteristic dynamic character. But it also brings sadness every time we have to wave someone goodbye. And this is exactly what this blogpost is about. Since editorial duties for this blog are performed on a volunteer basis by PhD students (in what little remains of their free time), this means that any editor’s tenure is inherently limited by his or her PhD track. Therefore, with some sadness, we have to say goodbye to Jonas, the founding father of the QuTech blog and involved from the very start. He finished his PhD and moved to Amsterdam. He was an amazing and creative member of the team and we would like to thank him for the time he has spent making this blog an inspirational place for quantum computing.

But of course he wouldn’t leave without equally capable replacement. And, since QuTech is growing, we also extended the editorial team. That is why we proudly announce the two newest team members, Tim and Matteo. Actually Tim and Matteo have been active on the blog for a while. So the time is definitely there for a more official introduction. Continue reading A word from an editor emeritus and new blog team members!

Quantum Computational Supremacy


by Adriaan Rol

Last week Google and collaborators published a paper in which they claim to have achieved Quantum Supremacy, one of the major milestones in quantum computing. The idea of quantum supremacy is to use a programmable quantum device to perform a task that is out-of-reach for any classical computer. Google claims to have solved a problem in seconds that would take tens of thousands of years on a state of the art supercomputer. The quantum supremacy experiment has been a long-standing milestone in the field of quantum computation, and as such, skepticism has arised; soon after publication of the article a group in IBM research has challenged the results [1].

Rather than joining in on the controversy of whether or not Google has really achieved quantum supremacy , I want to focus on some more basic questions: what is quantum supremacy, how does one demonstrate quantum supremacy and why is this such an important milestone?
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Quantum internet: at the verge of an emerging technology


by Bas Dirkse

The internet as we know it today has become an integral part of our lives. We use this piece of technology on a daily, hourly, almost continuous basis. We use it at work, to relax, to socialize, to fact check our friends during an argument and even to control the thermostat at our homes. We can definitely claim that, despite the internet bubble in the 90’s, the technology has far outperformed its expectations of the early 60’s and 70’s in the societal and financial benefits it provided. Will the same bright future be reserved for the quantum internet? Will it deliver the same amount of societal and financial benefits to the world as its classical sibling has done? Continue reading Quantum internet: at the verge of an emerging technology

Counting women in physics


by Floor van Riggelen

Take a close look at this famous picture. These are the people who attended the fifth Solvay International Conference (1927), where the leading physicists of that time discuss the newly formulated quantum theory. What stands out to me is that this is quite a homogeneous group: 28 white (including Jewish), middle aged guys, plus Marie Curie. Of course, these were different times. Comparing this to QuTech in Delft, the place where I work, (an example of a physics research environment in general) there are some improvements when it comes to diversity. Currently 23% of the QuTech employees are non-European and 17% percent are female, according to a recent official review [1]. However, a quick count on the QuTech webpage will tell you that if you only look at scientists and technical staff [2], this percentage drops to about 10%. At QuTech there are still several scientists who are the only woman in their research group. Looking at it in this way, it seems that not much has changed in almost 100 years of quantum physics. Continue reading Counting women in physics

Quantum Information Needs Protecting, and Here’s How to Do It


by Christophe Vuillot

Quantum physics is the strange and counterintuitive theory of physics governing the tiny world of atoms, electrons and photons. To access such small and ephemeral phenomena, scientists deploy advanced techniques to isolate and manipulate what can be destroyed by the tiniest breeze. Can they further protect these phenomena and make them survive to reach the scale of our life? This will be required to build a functional quantum computer. Continue reading Quantum Information Needs Protecting, and Here’s How to Do It

Happy Easter: looking for Quantum Eggs


It’s that time of the year again: the Easter Bunny comes by and hides his eggs. Everywhere you look he hid them: in the flower beds in the garden, underneath your bed, even if you open the cupboards, eggs come rolling out. Eggs in all kinds of clear colours and, if you’re lucky, made of chocolate.

But, over the past year, the Easter Bunny spent his time studying some quantum mechanics. He was inspired and decided to do something totally different this year. Instead of eggs, he hid some quantum terminology in the puzzle below. Can you find all the quantum eggs he hid?

Happy searching!

Can you find all the words?[1]

[1] This puzzle was made at WoordZoekerMaken.nl.
[2] The second ‘l’ in millikelvin got lost during the hiding…

Stitching Qubits


How to add qubits to an array one by one.

by Anne-Marije Zwerver

So it is winter and it is cold. Cold? It is freezing! But the air is nice and dry outside, so you decide to take a wintery walk in the forest. If you’re in a part of the world where you can currently fry an egg on the street, just wander along in your head – this is a small gedanken experiment. The walk is nice, yet cold and by the time you arrive home, the only thing you want, is to take a nice and warm shower. You turn on the tap and you feel the water running, splashing on your arms and shoulders, slowly defrosting your fingers. But then, for goodness sake, your roommate turns on her (cold) tap and your water temperature rises instantly. In a reflex, you jump out of the water jet, your skin already showing red stains. Luckily it was just an instant and soon you can go back into the shower. But then, of course, your other roommate needs some hot water and with a scream you, again, jump out of the now ice-cold shower. Time for a cup of tea…

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