Our paper Positivity in the presence of initial system-environment correlation has been published in Physical Review A!
The constraints imposed by the initial system-environment correlation can lead to nonpositive dynamical maps. We find the conditions for positivity and complete positivity of such dynamical maps by using the concept of an assignment map. Any initial system-environment correlations make the assignment map nonpositive, while the positivity of the dynamical map depends on the interplay between the assignment map and the system-environment coupling. We show how this interplay can reveal or hide the nonpositivity of the assignment map. We discuss the role of this interplay in Markovian models.
Theoretical physicists rely on their blackboards like priests on their pulpits, or like news anchors on their desks. We have very strong opinions about them. Markers vs Chalk? If you like markers, what brand of markers, and how thick? And then, do you write on the whiteboard, the glass window, or just simply, special wall paint? If you like chalk, what kind of chalk? Different brands crumble in different ways. Do you like colored chalk? Do you prefer to write on green or black board?
I am old fashioned about this. I like white chalk on black boards. But, I found that I’m allergic to chalk dust, and I’ve been forced to use markers on white boards now.
There is a photographic art exhibit about the Blackboards of Quantum Physicists. Some pictures are cool. In some others, I feel that the physicists tried to ruin how authentic the writing were, either by making them too nice, or by trying to sabotage them. Either way, I think this kind of works as a way to convince the public to not be scared by our crazy equations.
I have just come back from Hong Kong, where I was collaborating with the group of Prof. GuanHua Chen. We are interested in studying mathematical properties of the Hierarchical Equations of Motion from a Master Equation point of view. This was a very productive visit.
I also had a wonderful time exploring the city, and finding great food everywhere.
The Bremen Center for Computational Materials Science was host to the International CECAM-Workshop
Graphene: From band structure to many-body physics. See the workshop program here. This was a fantastic conference, with many of the leaders in the field.
Here is one of the Workshop pictures in front of the Bremen Townhall
I just came back from a delightful vacation where I reread The Baroque Cycle. The Baroque Cycle is a series of novels published in three volumes Quicksilver, The Confusion, and The System of the World in the genre of historical fiction about the rise of natural philosophy, important developments in economics and politics during the enlightenment. It is insanely ambitious, imitating literary styles from the era. It is insanely detailed. One of its major characters is Isaac Newton, both in his roles of the greatest natural philosopher ever, and as the master of the Mint, reforming the financial system in England.
Through out the books, references are made to a list of sins that Isaac Newton kept. In this list, he detailed every sin he ever committed. Curiously, the real documents including this list has been found by historians, and published on the internet. Check out the real list of Isaac Newton’s sins here.
Our paper Unification of witnessing initial system-environment correlations and witnessing non-Markovianity has appeared in Europhysics Letters. Previously mentioned here.
Our other related paper, titled Dynamical role of system-environment correlations in non-Markovian dynamics has been published as a Physical Review A: Rapid Communitcation. Paper previously mentioned here.
Quantum theory is the most accurate and well tested theory ever. However, it is difficult to understand without the proper mathematical background, and challenges common intuition. This makes it a target for crackpot attacks.
Scott Aaronson has gotten into a fight in his blog with the quantum denialist Joy Christian. This fight has many of the usual ingredients: angry comments, dares, misconceptions, made-up language, etc. War was declared in this post by Scott, and attacks were made in the comments to that post. This prompted Scott to follow up with a second post that is even more interesting. What makes it stand out is that 1) there is a $200,000 in line, 2) Scott has been gracious enough to study Joy’s papers, and find a central, basic and quite obvious mistake that makes the whole argument fall apart, and 3) Scott is asking for FQXi, Perimeter Institute and Oxford to cut all connections to Joy!
This has caused another debate in the comments section of the second post. Is this feeding the troll? Is this going to far? Isn’t this empowering Joy Christian more, instead of deflating him? Why pick on him, instead of any of the other quantum deniers? Even people from FQXi have posted in the blog.
Is this just another internet fight? Is this an example of what Neal Stephenson wrote in Cryptonomicon:
Arguing […] on the Internet is a sucker’s game because they almost always turn out […] to be indistinguishable from—self-righteous sixteen-year-olds possessing infinite amounts of free time.
Or is this how open science should be? After all, it does bring attention to unpublished work, focuses examination by leading researchers, and gets quick results. Just because the result invalidates the idea, was it wasted time and resources, or was it part of how open science should be done?
Is there a code of conduct for Open Science to differentiate between internet fights and good science?
Sean Carrol created a flow chart such that fundamental particles can determine which particles they are based on their physical properties and quantum numbers.
This should clear up most particle personality confusions.