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 After all, it does bring attention to unpublished work, focuses examination by leading researchers, and gets quick results.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.

We have posted yet another paper in the arXiv. It has been some intense weeks lately.

Unification of witnessing initial system-environment correlations and witnessing non-Markovianity

We show the connection between a witness that detects dynamical maps with initial system-environment correlations and a witness that detects non-Markovian open quantum systems. Our analysis is based on studying the role that state preparation plays in witnessing violations of contractivity of open quantum system dynamics. Contractivity is a property of some quantum processes where the trace distance of density matrices decrease with time. From this, we show how a witness of initial-correlations is an upper bound to a witness of non-Markovianity. We discuss how this relationship shows further connections between initial system-environment correlations and non-Markovianity at an instance of time in open quantum systems.

This paper is related to the previously posted paper.

Another subset of collaborators and I have posted a new paper in the arXiv:

Positivity in the presence of initial system-environment correlation

Dynamical maps can be nonpositive due to the constraints imposed by the initial system-environment correlation. We find the conditions for positivity and complete positivity of such dynamical maps by using the assignment map. Any initial system-environment correlations make the assignment map nonpositive, while the positivity of the dynamical depends on the interplay between the assignment map and the system-environment coupling. We show how this interplay can reveal and/or hide the nonpositivity of the assignment map. We discuss how this is related to many Markovian models.

This paper was done in collaboration with Kavan Modi and Alán Aspuru-Guzik.

Our new paper has appeared in the arXiv.

Dynamical role of system-environment correlations in non-Markovian dynamics

We analyse the role played by system-environment correlations in the emergence of non-Markovian dynamics. By working within the framework developed in Breuer et al., Phys. Rev. Lett. 103, 210401 (2009), we unveil a fundamental connection between non-Markovian behaviour and dynamics of system-environment correlations. We derive an upper bound to the derivative of rate of change of the distinguishability between different states of the system that explicitly depends on the development and establishment of correlations between system and environment. We illustrate our results using a fully solvable spin-chain model, which allows us to gain insight on the mechanisms triggering non-Markovian evolution.

In this paper we studied how certain measures of non-Markovianity are related to the development of correlations between a quantum system and its environment. This was a collaboration with Laura Mazzola, Kavan Modi and Mauro Paternostro.

I was invited to the Quantum Discord conference in Singapore, organized by Kavan Modi of CQT.

This conference last January brought a big part of the community together for the first time. It was very exiting, with a lot of nice informal discussions, and the great food that characterizes Singapore.

Also, there it was announced a blog dedicated solely to Quantum Discord. This is a good resource to follow all the new papers on the subject.

Our paper, Non-Markovian Open Quantum Systems: System-Environment Correlations in Dynamical Maps has been published!

Abstract: We construct a non-Markovian dynamical map that accounts for systems correlated to the environment. We refer to it as a canonical dynamical map, which forms an evolution family. The relationship between inverse maps and correlations with the environment is established. The mathematical properties of complete positivity is related to classical correlations, according to quantum discord, between the system and the environment. A generalized non-Markovian master equation is derived from the canonical dynamical map.

You can read it for free for the next couple of weeks in: International Journal of Quantum Information Volume: 9, Issues: 7-8 (2011) pp. 1617-1634

I've been traveling a lot lately, you might have noticed how I have been unable to update the blog frequently. Here is a quick update of where science has taken me.

November

Dresden - There I visited the group of Wanter Strunz. They are experts in open quantum systems and quantum optics, and we had much to discuss about open systems with initial system-environment correlations. Dresden has some stunning architecture.

Ulm - Susana Huelga invited me to the beautiful city of Ulm. I'm friends with many people in her group, and this was a great opportunity to catch up, and discuss some new research ideas.

December

Hong Kong - GuanHua Chen invited to Hong Kong University where we worked together on open quantum systems, master equations and quantum transport. Also, during these days, I was able to participate in the CECAM Workshop on Simulating and Modeling Emerging Electronics. This was a fantastic conference where I learned about the challenges of nano-electronics. This was a fun and intense visit. Fun, because Hong Kong is a very fun city to explore, and has amazing food. Intense, because the conference was very productive, with a lot of ideas flying around.

My paper on Non-Markovian Open Quantum systems has been published in the Special Issue of International Journal of Quantum Information (IJQI):

Non-Markovian Open Quantum Systems: System-Environment Correlations in Dynamical Maps

We construct a non-Markovian dynamical map that accounts for systems correlated to the environment. We refer to it as a canonical dynamical map, which forms an evolution family. The relationship between inverse maps and correlations with the environment is established. The mathematical properties of complete positivity is related to classical correlations, according to quantum discord, between the system and the environment. A generalized non-Markovian master equation is derived from the canonical dynamical map.

This paper is an updated version of my 2008 preprint.

Last week, here at the BCCMS we hosted the CECAM conference titled "Perspectives and Challenges of Many-Particle Methods". This was a very good conference, bringing together leaders from all sorts of ab initio and many-body methods. The program is here.