Cooling a Hot Photon Wind (part 1)

Difficulty    

Combining low temperatures and high frequency signals is becoming ever more important in the development of quantum technologies. In QuTech for example transmon based devices use some signals in the 2-10 GHz range and spin qubits use even higher frequencies; over 20 GHz. It is desired that the noise in the working bandwidth should be as low, and as cold, as possible, but these devices can be also quite susceptible to unwanted photons at much higher frequencies, 50-100 GHz, leading to extra quasiparticle generation or photon assisted tunneling that can destroy the fragile quantum states. This post aims to be an easy to read tutorial and guide as we look at a model to reduce the distribution of thermal photons from a high temperature to a low one. In the particular case of a 1-dimensional coaxial cable carrying photons from room temperature towards a cold sample mounted in a dilution refrigerator. I’ll try to convey some intuition how this model behaves and what this means for cryogenic design.

Continue reading Cooling a Hot Photon Wind (part 1)

European affairs

Difficulty    

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

Once upon a time in the Netherlands …

Difficulty    

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 …

A Cloud Quantum Computer Business Plan

Difficulty    

by Christian Dickel

Quantum computing and nuclear fusion are potential 21st century technologies based on 20th century physics and neither of them is currently market ready. But while they are sometimes bunched together as fascinating concepts that will at any time be twenty years away from being realized, some estimate the timescale for the commercialization of the quantum computer to be much shorter now. Quantum computing is currently in a hype phase: The company D-wave has already sold a few quantum annealers based on flux qubits for millions of euros. They can solve certain optimization problems, but their computational advantages are a topic of debate. Google, IBM, Intel, and Microsoft are major commercial companies investing in quantum technologies right now. Several startups such as Rigetti Computing and IonQ have been founded recently with the goal of commercializing quantum computing. A list of such companies can be found here.
Continue reading A Cloud Quantum Computer Business Plan