Sometimes I stay awake in the night thinking – how soon will the results of my work become useful for humanity? Well, better get up and do something about it! And so a few months ago we have started a new scientific equipment company, based on research breakthroughs in the field of topological quantum matter.
The new company is called ‘Pittsburgh Instruments’ to honor the long-standing tradition of naming something after a city. We currently have three employees, and a distinguished board of advisers though some of the founders of our technology are sadly, no longer with us. The website for the company, along with the Kickstarter page are going online as I write this.
We actually already have a prototype of our first instrument. Please welcome:
Chernnumberometer 1.0 from Pittsburgh Instruments, going on sale December 31 2016
It is a sleekly designed high tech gadget which can measure a Chern number of anything that fits inside! Just open the door, put your item of choice in.Select Integration Time. Press start. The machine will rotate the object to examine it. Then the digital display will show you the answer. For example, if you put a doughnut inside it will read 0, if you put an orange it will read 1. You can read pretty high numbers if you put in something like this. Give it a try! You can also easily switch a topological invariant that you want to measure from Chern number to a Z2 or a determinant of a scattering matrix for 1D systems. Nevermind that labels say ‘Chicken’ or ‘Popcorn’ – this is an inside joke from the company, we like to be cool like Android developers. For example ‘Defrost’ refers to a very advanced renormalization group-based algorithm.
Our target population are theoretical physicists who have an incessant desire to know things about physical systems that cannot be measured. This compact and elegant Chernnumberometer fits on an office desk, in the coffee area or even at your house! Priced at just $3,999 it also fits on almost any grant. Make sure to mention it in your next proposal!
(Some of the issues we are still working out are dynamic cooling, as certain samples we reported to get very hot. The final release might actually feature a helium compressor bumping the price to $53,999. Also, don’t try to measure Chern numbers of your pets or eggs)
This gif filmed in Tofino is from 2008 and it explains the ‘injector-detector’ device used to generate and measure spin currents. Charge currents flow to the left, while spin currents flow both ways.
It pertains, for example, to this paper we wrote: http://arxiv.org/abs/1208.3106 (this is an arxiv-only publication!)
Last semester I recorded 23 lectures on Solid State Physics for Undergraduate students. The first 15 lectures are following the wonderful texbook by Steven Simon “Oxford Solid State Basics”, and the last lectures cover superconductivity and advanced topics from Quantum Transport. This class can be a prequel to my Quantum Transport course and I hope it will be useful for students thinking of going into condensed matter research.
Because this is so great for binge watching, I am releasing the whole season at once.
So there is this great movie that you should totally go see, it is about an eccentric scientist who befriends a simple-minded neighborhood teenager and sends him backwards in time in a car converted into a time machine…
Something like this just happened in our lab. We started out a couple of years ago as a cryogen-free operation. Instead of relying of liquid helium, we used closed-cycle cryostats where helium circulates between a compressor and a cryostat and extracts heat from a vacuum-shielded volume. There are two reasons why cryogen-free systems are great – they save money on (pricey) liquid helium and they are easy to operate at a push of a button.
But in the meantime our generous university set up a helium liquefier, which supplies nearly-free liquid helium to us. And so now we built our first liquid helium setup – a dunker stick! It derives its name from a concept of dunking your specimen into liquid helium in order to reach a low temperature of 4.2 Kelvin, at which helium is stored in liquid form.
From the technological point of view, it is a step back compared to our cryofree setups. But we can use it for many quick measurements and tests, which is great.
Optical microscopy images of a silicon wafer covered with PMMA and silicon nitride. The structures appeared when silicon nitride was sputtered onto the wafer.
Last year was the 35th anniversary of the seminal paper by Bychkov and Rashba which introduced a spin-orbit coupling which is now known as “the Rashba effect“. It is a beautiful piece of physics that brings a bit of relativity into condensed matter world. Turns out, in an electric field (or under a broken symmetry) electron spins in a solid can behave as if they are in a magnetic field.
Anyhow, 35 years later the Rashba effect lives on and find itself at the frontiers of some of the hottest research of the 21-st century, as you can convince yourself by arxiving it (it is like googling but with arxiv.org).
So a few months ago Aurelien Manchon approached me and several other folks to be part of a review of what is the face of Rashba effect 35 years later. As with all manuscripts, preparation took forever, so we are celebrating the 35th birthday of Rashba effect one year later. But finally the paper it out there and we are hoping it can serve those who want to know how Rashba spin-orbit physics beats along with spintronics, quantum computing, topological physics and cold atomic research.
I learned a lot about spin-orbit interaction myself from working on this review, I also learned the difference between stirring and steering, as in ‘steering wheel’ not ‘stirring wheel’ (thank you, anonymous referee!).
Our University has sacrificed a parking lot to realize this project:
It is an expansion to the machine shop which among other things now hosts this helium liquefier:
Our lab is now connected to the helium recovery system, and we are building our first “wet” cryostat in which liquefied helium is used to cool a sample to 4.2 degrees Kelvin (-269 degrees centigrade). We are also now officially shopping for a used wet dilution refrigerator.