Monday, March 27, 2017

My talks on Entropy-Noise Correspondence

I am back from a loooong long trip into several cities in the US and Canada, where I gave a series of talks about my research.

In my trip to New Orleans for the first time I saw real palm trees! The city has its own character within its cheesy streets full of excited visitors and free storytelling stations! I was also excited to see Mississippi river that reminded me one of the cartoon I was watching when I was almost ten: the Adventures of Huckleberry Finn! At APS March meeting I enjoyed meeting some old friends from Japan, the US, Canada, Germany, Holland, Australia, and others. I gave a short talk about information contents of physical interactions and enjoyed learning many new things.

Later I traveled to Canada to give a series of talk in different places and to visit a research group for future collaborations. My schedule was very rich! I started with the University of Toronto, then I went to Waterloo to visit and give a talk at the Institute for Quantum Computation (IQC) on how to measure entropy in quantum systems. +

A planned I also visited the Perimeter Institute in Waterloo too, where I got my PhD degree 9 years ago. The building has changed a lot since then and I could not recognize many of its staff. There I gave a talk in the quantum foundations seminars about the new entropy-noise correspondence we found last year +

The talks turned out to falls into the interest of two communities: condensed matter theorists and quantum information theorists.

To provide equal opportunities to those not present in the cities yet like to form and express a judgement, I uploaded a short summary of my presentations here to be accessible to public. Please feel free to review.

M.H. Ansari

Sunday, March 05, 2017

Talks


If you happen to be near Aachen this week, come to hear news about entropy. (this link

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Quantum information seminar, Mar 09 11:00, Physikzentrum MBP2 116
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SPEAKER: Mohammad Ansari (FZ J├╝lich)
TITLE: Entropy measurement in quantum systems

ABSTRACT: Entropy is an important measure of information. Being nonlinear in density matrix, its consistent evaluation for a quantum system requires a formalism that allows simultaneous evolution of more-than-one-copy of density matrix. Recently in [MHA and Y. Nazarov, Phys. Rev. B 91, 104303 (2015)] a formalism for such evolutions has been proposed and [MHA and Y. Nazarov, Phys. Rev. B 91, 174307 (2015)] shows that such entropy correspond to physical quantities. Interestingly this correspondence is not equivalent to the second law of thermodynamics. In this talk I describe how to measure entropy flow in a quantum heat engine.

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Also next week I am in New Orleans. If you are attending APS March meeting I am going to give a talk in Session L52: Statistics of Ensemble Quantum Systems Wednesday at 11:50 AM in  Room: 399. 

Wednesday, February 01, 2017

A postdoc/PhD student position

A fully-funded postdoc/PhD student position is available to work at Peter Gruenberg Institute (PGI-2) in Forschungszentrum Juelich, near Aachen in Germany. For students the degree will be granted by RWTH university in Aachen. The researcher will work with Dr. Mohammad H. Ansari. The project can be started in the Summer or Fall 2017.

The purpose of the project is to develop the relations between quantum information theory and physics. For this aim we recently developed a new formalism called multiple parallel world technique. Our findings will be used to explore new phenomena in quantum computing, thermodynamics, and photosynthetic complexes in biology. The project requires that you have basic knowledge about quantum physics and information, e.g. density matrix, decoherence, Bloch equation, correlations, nonequilibrium statistics, quantum information measures, Keldysh techniques, etc.

We will collaborate with some theoretical and experimental research groups, such as the research group of Prof. D. DiVincenzo in PGI-2 and Prof. Y. Nazarov in Delft University of Technology, the Netherlands, et. al. The employed researcher will have the opportunity to visit our collaborators.

Everyone (Masters and PhD students and Postdocs) from all around the world are welcome to apply.

For full consideration, please apply as soon as possible, by sending your documents in *ONE pdf file* to "mansari AT gmail DOT com", including:

1. your academic CV,
2. your list of publications,
3. research interests on what makes your past research experience related to quantum thermodynamics, (no more than 300 words ~ two paragraphs)
4. the names, affiliation, and email addresses of 2 or 3 referees, (make sure they are willing to send letters on time)

More information about the research details as well as announcements (e.g. whether the position is still available or not) can be found at:
https://sites.google.com/site/mansari

Wednesday, November 30, 2016

A newly-published course book by Manoukian


December this year is almost the 10th anniversary of finding new degeneracy in area spectrum and finding heir application. (1,2)

Yesterday I was informed in an email from Springer that some of those results about area quantization have found their way into a  newly-published graduate textbook. Although this is not the first time that somebody writes about what I have done (see footnotes) but this time feels differently because my physics is now a part of a graduate course book.

Here is the book: "Quantum Field Theory II: Introductions to Quantum Gravity, Supersymmetry and String Theory (Graduate Texts in Physics.) written by E.B. Manoukian and published by Springer on September 2016).

I read some parts of it, yet not all, and to my point of view it is quite decent book in the field, well-written and organized, and clear. It provides interesting insights about recent developments in quantum field theory. More importantly it teaches how modern physicists think about quantum foundations, overall a must-read book for graduate students working on quantum field theory.

This is pretty exciting to see that the degeneracy of quantum area spectrum and its physical applications ten years after its discovery are now exercises for young students!

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Footnotes:

* D. Oriti, Approaches to Quantum Gravity: Toward a New Understanding of Space, Time and Matter (Cambridge University Press 2009) highlighted my research on black hole and area quantization.
          
* M. Aschwanden, Self-Organized Criticality in Astrophysics: The Statistics of Nonlinear Processes in the Universe (Springer London 2011) highlighted my research on cellular automata, self-organized criticality and nonequilibrium phenomena.

* A section 2.46.3 of the book: The Cosmic Compendium: Black Holes by R. W. Anderson has devoted only to explain my results on black hole.

* The article by L. Smolin, in Physics Today 59 Nov 44 (2006) highlighted some of my results on black holes http://dx.doi.org/10.1063/1.2435646 , etc.


Tuesday, May 17, 2016

News about entropy



Did you know that you have been calculating entropy incorrectly during your whole life!   This is at least what I claim to be true in a recently published paper titled: "A consistent flow of entropy."

A common approach to evaluate entropy in quantum systems is to solve a master-Bloch equation to determine density matrix and substitute it in entropy definition. However, this method has been recently understood to lack many energy correlators. The new correlators make entropy evaluation to be different from the substitution method described above. The reason for such complexity lies in the nonlinearity of entropy. In this paper we present a pedagogical approach to evaluate the new correlators and explain their contribution in the analysis. We show that the inherent nonlinearity in entropy makes the second law of thermodynamics to carry new terms associated to the new correlators. Our results show important new remarks on quantum black holes. Our formalism reveals that the notion of degeneracy of states at the event horizon makes an indispensable deviation from black hole entropy in the leading order.

This is a my contribution to special issue in Fortschritte der Physik for the Frontiers of Quantum and Mesoscopic Thermodynamics Conference. Link: arXiv:1605.04620

By: Mohammad H. Ansari