The remarkable effectiveness of math

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by Jonas Helsen

So this post will be a bit more, let’s say, philosophical. I’d like to share some of my thoughts on a particular subject which has always struck me when I was studying physics and also now while I’m doing it in what might be called a professional fashion. That subject is mathematics. More precisely it is mathematics as applied to physics. Now I won’t pretend to be anything close to a real mathematician, but when you need a math-person and there are no mathematicians around you can probably do worse than a theoretical physicist. In physics, and also in computer science, we use math; a lot of it. In fact I would say that, and I think most physicists would agree with me, that mathematics is the language the universe is written in. Or at least the only language capable of describing it in an efficient manner. People often marvel at the ability of mathematics to capture physical phenomena in an extremely accurate and efficient manner, often waxing philosophically about the inherent simplicity of the universe. Here I’d like to give some of my, fragmented and incomplete, thoughts on the matter. While I certainly think that the fact that nature is describable at all is a fact worth pondering over long and hard I think the prevalence of math in physics and its remarkable effectiveness is at least partly due to decidedly more down to earth cultural forces present throughout the history of mathematics.

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A day in the life of a Master student

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Author: Sophie Hermans

Hi! My name is Sophie Hermans and I am a Master student in the group of Ronald Hanson. I have started my MSc project about five months ago in the “cavity team”. Today I will take you along and show you what I do on a regular day.

There is no better way than to start the day with a freshly brewed, warm and strong cup of coffee.


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The APS March meeting

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By Jonas Helsen, Christian Dickel, Adriaan Rol, James Kroll and Suzanne Van Dam

The March Meeting of the American Physical Society, held every year in March (hence the name) is probably the largest meeting of physicists in the world. Held in a different city in the US every year it is a five day long whirlwind of talks, discussions, meetings, catching up with old friends and making new ones from all over the world. Since a sizeable subsection of the March meeting deals with quantum information processing (as of this year we are officially a Division!) a large group of Qutech scientists made the trek to New Orleans, both to speak about our latest developments and to learn about science going on all around the world. For this occasion we asked a few people to jot down their impressions of this weeklong carnival of physics and have bundled them in this blogpost. We will also add some pictures which hopefully convey the general scale and feel of the March meeting.

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Why turning a ket into a cat may or may not be a good idea

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By Adriaan Rol

When I’m at a party people often ask me what I do.

There is a lot of things I can talk about: why is a quantum computer interesting or useful , or:  what do I actually do during my day. But quite often people end up asking a confused question about this curious story of an undead cat. In this blog post I will try to shed some light on this case as well as delve into the question of why we use these kind of stories.

Dead? Or alive? Or both?

When trying to understand a new theory we physicists love our thought experiments.  We take some mathematical model of the world, change some parameters to see how it behaves and try to extract some rules of thumb or intuition from it. Continue reading Why turning a ket into a cat may or may not be a good idea

Playing the Quantum Ballgame

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By Jonas Helsen

One of the things that is often repeated about quantum computing is the idea that a quantum computer is somehow more powerful than regular computers because, when considering a problem it can “try all possible solutions at once”. Let’s get this out of the way first and say that this is not exactly the case. While we would very much love a computer that tries all solutions at once (this would be extremely useful) quantum computers sadly aren’t quite this powerful. Of course, as with all good clichés it does contain a grain of truth. In this blog post I will try to explain in a (sort of) simple way what makes quantum computers more powerful than classical computers.

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Playing cards with quantum entanglement

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by Gláucia Murta

You have probably heard that entanglement is a very strong correlation way beyond anything we can conceive classically. However, as we’ve seen from Jeremy’s post , these strong correlations by itself do not allow us to send any information to the other part. So what can we use entanglement for?… To play games!

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My Quantum Kitchenette

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by James Kroll

There are many things that might pop in to your mind when I propose that you may be able to do quantum mechanics in the comfort of your own home. A ‘quantum kitchenette’ is probably not one of them.

This may have been a bit facetious, but it is true that many of the things you find in your kitchen such as a fridge, a microwave and beer bottles are perfectly analogous to the tools that are used in labs around the world to perform cutting edge experiments in quantum mechanics – in particular with applications in quantum computing.

These tools are technically challenging to fully understand, very expensive and equally impressive in their capabilities. As an experimental physicist, one of the most enjoyable parts of the job is using this equipment, understanding fully how it works so we can use and repair it if need be, but also the small idiosyncrasies that each specific piece of equipment acquires over time.

On a personal level, you really do develop an intimate relationship with your equipment, such that in some cases you are the only one who can use it reliably. A shorter way to summarise the connection might be: “Boys and their toys”, or whatever phrase would convey the same meaning in a more egalitarian manner.

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Nanoscale Superstition

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by Michiel de Moor

In our cleanroom, we use nanofabrication techniques to combine materials in a precise and controlled way in order to study the wonders of quantum physics. For a nice introduction on the topic, I recommend reading Madelaine Liddy’s blog post. This post is not about nanofabrication specifics, but more about the people involved in the process.

Doing nanofabrication takes up a significant amount of time. Often it’s very difficult to understand what the important parameters are, and outcomes can seem random. As scientists, we should be rational and analyze the problem, then test possible solutions until we understand what is happening. But as people, we are susceptible to the same kind of magical thinking that makes people believe lightning strikes are a sign of Zeus’ displeasure.

As with cooking food, every research group will have their own fabrication recipes (which are, of course, the very best in the world). Continue reading Nanoscale Superstition

Climbing the Ivory Tower

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by Julia Cramer

After some years of doing science in the dark basement of a physics building, one may wonder: ‘who am I?’ Searching for answers at Google Images, there turns out to be a distinct difference between the stereotypes ‘scientist’ and ‘physicist’. Surprisingly, a ‘scientist’ always wears a lab-coat plus safety glasses. The ‘scientist’ works in a clean lab environment, handling chemicals and a microscope. According to Google, the ‘scientist’ is happy and young, can be male or female, black or white.

How large is the contrast to Google’s ‘physicist’: an old, somewhat otherworldly, serious man wearing thick glasses. The man standing in front of a whiteboard is writing down equations and drawing spheres on a blackboard. It is interesting to notice that Google barely makes a distinction between ‘physicist’ and ‘professor’. Leaving behind the fact that both a ‘scientist’ and a ‘professor’ can be an academic in any kind of field, I wonder why the ‘physicist’ never conducts any experiments.

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How to Bake a Quantum Cookie

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by Madelaine Liddy

Sweet Grandmother’s Spatula! After pulling out your fresh cookies from the oven and taking your first taste you notice that in creating your cookie dough, you accidentally mixed up the sugar and salt. Now your dreams of enjoying that oh so sweet sugar cookie have been dashed away and you are left with a confectionary calamity. However, all is not lost…. your seemingly imperfect dough with salty defects can be fixed to result in the masterpiece of baked goods. Thus I present to you, the challenge of baking the chocolate chip and sea salt cookie. When balanced correctly, these two flavours can enhance each other to create complex layers of pure deliciousness.

Now you may be asking yourself, what does this have to do with quantum mechanics? Picture your salty cookie, full of defects within its dough, seemingly useless. However, if you add the right amount of chocolate chips in places as accurately as possible, you will achieve the right balance of flavour and achieve the perfect chocolate chip and sea salt cookie, a true baking delicacy. Likewise, in experiment, we begin with a crystal that contains lattice defects with quantum properties. In the general scheme of things, the goal is to add other materials within or near the substrate in as precise a location and concentration as possible so that we may enhance, control and measure these defects.

So with that in mind… let’s get baking!

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