Sunday, March 05, 2017


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

Quantum information seminar, Mar 09 11:00, Physikzentrum MBP2 116
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.


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:

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!


* 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 , 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

Thursday, February 11, 2016

Hearing a sound from a billion years ago!

Today is a day for cheering. After many years gravitational waves have been finally reported to have been detected. In two separate detectors, in west and east coasts of the US, almost simultaneously it was detected that earth got shrunk a tiny bit from a gravitational curving pulse. Many researchers have been sweating for decades to make these detectors happen.

Let me explain what has been discovered. An early approval for the theory of general relativity in 60's was based on the following fact: the presence of a heavy object, like our sun, will causes its surrounding spacetime to be curved. This has been observed from the following experiment: the straight path on which light travels in the universe from A to B, if passes adjacent to a heavy object, will bend a bit toward the object, thus the path will not remain a straight path anymore.

Now, consider two heavy objects crazily rotate around one another with a crazy speed (a half of speed of light). Right before they merge they make a lot of ups and downs in the spacetime in between. This turbulence in the very spacetime fibres propagate to others places, similar to how tsunami waves propagate in the ocean. In other words, gravitational field is self-interacting; this means that it sources itself. It curves the space around itself because it carries mass/energy by itself much like a star does.

If the objects are many light years away, the waves passing through the Earth today makes a bit of stretches and squeezes in the radius of earth, something of the size of less than the radius of proton! This has been detected last year at LIGO detectors and today was reported, and peer reviewed already in the PRL.

From what they received we assume that the waves came from two 30-solar-mass black holes curling up around one another in a death spiral, a billion light-years away from us. This is a better-than-expected source for LIGO and sometimes the universe is nice to us!  In fact a billion years ago two heavy stars fell in love with one another and played hand in hand like kids, and today we got a bit of their happy sound!  Doing such an amazing science is similar walking a tightrope between surly curmudgeon and starry-eyed cheerleader. 
The last thing to notice: If you are sad you do not get cited more often, apparently Einstein’s prediction of gravitational waves has been cited only a few times!

By: Mohammad H. Ansari