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

Diary of an international student at QuTech


by David Maier

QuTech not only offers a wide range of interesting research, but also a diverse group of employees from numerous countries around the world. As a student from the far away country of Germany I was very curious if I would be able to fit in and overcome the cultural differences. Four months ago I came to Delft for my master’s project. In this little piece I would like to tell you from a humorous perspective about some of the challenges I faced as an international student coming to Delft and how you can overcome them too.

Disclaimer: this text contains irony.
Continue reading Diary of an international student at QuTech

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

A quantum network stack?


by Axel Dahlberg

Summer is approaching fast! The days until vacation are getting fewer and fewer. But before you can relax at a beach with a cold drink you need to send a bunch of emails. However for some reason the software allowing your computer to connect to the Internet has suddenly vanished. What can you do? Well, maybe you can just manually do whatever this software does. It can’t be too hard right? Or can it…?

The network stack, a collection of of software used by computers to connect to each other and run applications over a network, such as e-mail, social media, file sharing, video streaming etc., used by today’s Internet is crucial to its operation. You use it everyday, but do you know what it actually does? When you send an email to your colleague, how is your email actually transmitted across to a different computer?

Continue reading A quantum network stack?

European affairs


by Barbara Terhal

Recently I had to deal with some bureaucratic business involving a European grant. It concerned the transfer of this grant from one academic institution to another in the form of an amendment.
The transfer had to take place through the interaction of a variety of people, project managers, scientists, upper- and lower-level secretaries, in a EU web portal.
The portal is somewhat like a virtual castle in which one occasionally discovers a door to a hidden room. Once open, the hidden room turns out to give access to new functions and role play, inviting to dress-up and bal masqué, going far beyond the promise of the

Continue reading European affairs

Who’s afraid of Majorana qubits?


by Guanzhong Wang

Don’t hide it; don’t deny it. I know every time you, my dear friend in or related to the quantum computing community, hear about the words “topological qubits”, you raise your eyebrows slightly and say to yourself, “weird”… Pretend no more! We know you are puzzled why anyone would want to embark on the journey of making a topological qubit and how on earth they go about doing it. In this new series on topological qubits, we will try to explain to you why building such a seemingly unconventional qubit is rather fun and is even one of the natural choices when it comes to quantum computing.

I will start in this post with a virtual lab tour, hoping to give you an overview on where and how we look for the basic building blocks of a topological qubit—a Majorana bound state in condensed matter systems. From the particle that Ettore Majorana envisioned on a piece of paper to the nanowire devices and then back to the blueprints for a topological qubit, this will be a journey linking seemingly strange ideas to real, tangible chips in cryostats. If you’ve ever got curious about a Majorana qubit, gone through some reviews and tutorials but still wonder how experimentalists try to build them, this article is totally for you. If you haven’t, I hope it will arouse your interest in doing so! Continue reading Who’s afraid of Majorana qubits?

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
[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…

Continue reading Stitching Qubits

Once upon a time in the Netherlands …


by Freeke Heijman

Usually this blog is about research topics. When I was asked to write an item on the political aspects of quantum, I was excited but also a bit hesitant: would this parallel universe, in which politicians, executives and government officials rule the world, be interesting to the research community? What could I share without breaking rules of confidentiality while keeping some of the juicy details that make life interesting? How could I bridge the gap between these two worlds that are so completely different in their values, methods and people?

I decided to take up the challenge. After all, these dilemmas are the very same ones people with two legs in two different communities have to deal with every day. It is about making an effort to understand and find your way in different cultures and trying to get across some glimpse of these worlds to the people you work with on both ends. The last part almost feels like a mission impossible to me – the more reason to give it a shot in this blog! Continue reading Once upon a time in the Netherlands …

QuTech interview: Prof. Wolfgang Tittel


It is a cold Monday afternoon when we have our appointment with Wolfgang Tittel, professor in physics and specialized in photon entanglement, quantum teleportation, and quantum memory. As we expect from a busy professor, he is still in another meeting when we arrive, so we decide to wait two meters outside his door. When we go and check if he’s almost done with this other meeting, his office suddenly appears deserted. In a vivid demonstration of his expertise, he seems to have teleported away from his office…

Luckily, he reappears quickly and lets us into his spacious office. One wall is completely covered by a large whiteboard, covered in scribbled equations and diagrams. Clear signs of occupation by a physics professor.  Professor Tittel himself welcomes us with a smile, clearly relishing the opportunity to talk about his work. What follows is an interview with professor Tittel, shortened and lightly edited for clarity.

What type of research do you do?

My research lies in the framework of the quantum internet. More precisely, it is about quantum key distribution (QKD) and the creation of quantum key distribution systems over very long links. This requires quantum repeaters. To create the quantum internet, we send photons down an optical fiber, but, just as in standard telecommunication, these photons get lost at some point. In standard telecommunication, you can use amplifiers to boost the signal level, but for quantum internet this doesn’t work because of the no-cloning theorem. Instead, we can use a so-called quantum repeater.

Continue reading QuTech interview: Prof. Wolfgang Tittel