Sunday, February 24, 2013

So, you want to do science, uh? (Rants to Young Scientists Part I: Citations)

Sometimes, I wish someone had made that statement and followed with some advice, real world advice. I mean, Medawar's "Advice to a young scientist" was great in convincing me science was about inquiry, patience and common sense —the well-known adage of  1% inspiration and 99% perspiration— but, after a few years into the academia, I wished someone had told me about the dark side of research: citation engineering, steering and hiding just to mention some examples. I mean, all these lay inside the gray area between ethical and unethical behavior and a simple search brings up discussion forums on the topic in all the scientific communities from social to natural sciences.

I guess, right now, it is my frustration talking: I have seen a couple of recently published articles related to our late work that doesn't even bother to cite us even when we have introduced some basic concepts or techniques on the topic, our manuscript was published at a major journal and, also, a simple scholar search brings out our papers on the top of the list.

I'm curious about the motivation behind these practices. Discarding those cases when there's truly no knowledge about the previous work and results have been re-derived from the start — t happens, believe me—, I can imagine that some guys are so worried about fame and recognition, that they try to bring their work and only their work into the playground to increase the visibility of their papers above similar results from other groups. Some other guys may wish to engineer their metrics by increasing the citations to this or that paper, even in cases unrelated to the matter at hand, in order to fulfill requierements of evaluation agencies. Or maybe I'm completely wrong and don't understand the motivations behind us, human beings. 

So, you want to do science, right? Well, it's the best job you will have if you are into it. It's not as logical, ethical and "pure" as you would expect. Shit happens even in the ivory tower of academia but the good things is that the nice ethical guys are more than those in the gray side of the ethical/moral spectrum. The best part is: it depends on you to keep it that way. Cite, cite truthful, cite well. Sometimes your superior will have the last word —been there— just don't go down without raising the point, that will get you an explanation about how it is not unethical or amoral engineering or steering citations —it's up to you to buy it or not, I didn't—.

Wednesday, February 13, 2013

Our latest paper: The exact solution of generalized Dicke models via Susskind–Glogower operators

Our latest paper The exact solution of generalized Dicke models via Susskind–Glogower operators  has been published a day ago in J. Phys. A: Math. and Theor.  The Dicke Hamiltonian is a workhorse of Quantum Optics, it describes the interaction of a collection of identical two-level systems with a single mode electromagnetic field under the long wave and rotating wave approximations. Surely, you will be thinking: "well, that model conserves the total number of excitations and parity; then, it's trivial to find its proper values and states." Well, it is trivial to solve the system but, as far as I know, it's not that trivial to follow the dynamics of a large ensemble under this model. 

Actually, I was looking at recent solution to a nonlinear version of this model via the Bethe ansatz method and  I got frustrated that even by using this method it was hard to follow the dynamics of a qubit ensemble of size twenty. So, Héctor and I sat down and applied a right unitary method that we had used to follow the dynamics of a quantum Landau-Zener-Majorana Hamiltonian a few months ago. It was trivial to extend the approach from a single qubit to an ensemble but the solution was not elegant enough, as you can see in the first part of the latest paper. So, we tried an alternative, instead of thinking about transformations we just thought about algebraic manipulation of the Hamiltonian at hand. After a few tries, we realized that one particular arrangement allowed us to write the evolution operator as the transform operators acting on the evolution operator of a tridiagonal matrix in the ensemble basis that depended only on the number operator. From there, it was all downhill because calculating the evolution operator of such a semi-classical-like Hamiltonian is quite simple, numerically, even for very large matrices and applying the transform operators on the initial states was easier than applying them on the time evolution operator. 

At the time when we were writting the paper, I only had my dual-core i7 laptop with 8GB of RAM, but it only took a few hours to follow the dynamics of an ensemble consisting of twenty-five qubits interacting with a coherent field with as mean photon number of twenty five. Now, I have done some simulations in my eight-core i7 desktop with 64GB RAM and I can follow the dynamics of a hundred qubits overnight with a very inefficient program. I'm hoping hat I will be able to simulate four or five hundred qubits interacting with large coherent fields as soon as I have time to sit down to think about this problem again.

Oh, I forgot to tell you. Once we obtained a result for just the Dicke model we extended the approach to include independent nonlinearities in the field and the ensemble, an approach a little bit more general than that of the guys in the Bethe ansatz method.

So, I hope you like our approach, use it and cite us in the future. You can find the Journal version at JPAMG. If you don't have access, we have prepared a manuscript with the final published version but without the journal format and uploaded it to the arXiv.

Sunday, February 10, 2013

Last weekend movies (6th week of 2013)

It was a hell of a week but I managed to watch a movie in pieces,
  1. The Man with the Iron Fists, *
    The one star is because I liked martial art movies back in the 80s. The music is good but not right into the asian fighting movie mood, I think. Well, I just didn't feel it. 
I'm on the mood of some real asian epic movies, just like Chibi, which I don't remember watching the second part. I need to go to Asia sometime soon to recharge my epic martial arts film batteries.

Sunday, February 3, 2013

Last weekend movies (5th week of 2013)


It's time to try to catch up with so many movies that I have missed. I'm gonna try my best to watch at least one per week, 
  1. Looper, ****
    I think I will become a fan of Joseph Gordon-Levitt. He's a good actor and it seems like he's all around good guy. Now, I really don't get it why the future mafia takes such big troubles to dispose of enemies and has no trouble at murdering a wife. Anyway, the stars are for a nice story, where I can see and feel many loopholes, with an awesome ending. Truth be told, I don't like everyone lives happily forever endings. I rather have a good masterpiece novel ending where sacrifices have to be done. Such is life.

So, any suggestions?

Saturday, February 2, 2013

Sorry, we're open!

Hello world,

I have decided to come back online to seek catharsis. You see, I have been recently appointed Investigador Titular A at the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE). I am a newbie to the rat race of tenure track positions so I did the most stupid thing I could have thought about: Start developing old ideas, trying to collaborate with well established researchers, get a couple of students and, basically, try to publish or perish... Bad idea.

Why, would you ask. Well, it happens that I am also getting married next May.

In short, I have put myself in the most crazy situation I have ever put myself into in my life. Now, I am co-responsible for two doctoral students, teaching a graduate class, trying to publish some papers, searching for a good idea to write a grant due to the end of February, taking care of a friend's house, traveling to and fro for wedding matters, and screwing up things now and then.

For example, I just realized I got an awful typo in the last equations of our latest prepint! I completely forgot to type the interaction terms! 

Sooooo...

It's time to keep doing what I have done all this time, Prepare lectures a week ahead, try to finish projects well ahead of deadlines, and add some rules like fixing a precise hour for meetings with the doctoral students and working at most with two research projects at a time. Also, I need to let go and that's why I'm back.

Sorry, we're open!

Monday, June 25, 2012

Changes related to lists of Papers, Books and Movies

As you can see, I have been unable to keep posting what I am reading/watching in the last month. I have realized I was using a time consuming format for this end. I have just decided to try twitter to list whatever I'm consuming as soon as I'm consuming it, so if you want to know what I am reading or watching please use the tweet box at HambrientosVagabundos.org or follow me in twitter: @BMRodriguezLara

Here, I will keep posting my unpredictable rants and even more unpredictable musings. Sometimes, when I find a paper/book/movie that really amazes me, I will post about it here.

Thank you

\B

Wednesday, June 20, 2012

Preacher

The old man came into town in silence, bent by the weight of a hiker's backpack and set camp in the remains of the old university. After a couple of days, he emerged with a heavier looking backpack and a tote bag filled with books. Then, he spoke at the town's market.


They said anarchy came with the riots and those were brought by the drought, famine and general collapse of the economy but I know that's a lie we tell ourselves to rationalize our existence. Truth is, a false anarchy started  when everybody else became just a tool for personal gain and success. We told ourselves: money is needed to eat, to dress, to have fun and find happiness; nobody ever thought you cannot eat money. The search for happiness was lost and that of power, wealth and fame substituted it at large. The inner self diluted by the wash of pose. True anarchy would have been deliverance, instead the false anarchy of vacuity and personal delusion took hold with every inch gained by the dream of greed. True anarchy would have been better: in the sense of liberating freedom and inner peace. Instead the vice circle of selfishness reinforced itself and brought us here. There's a way out but... Could you trust me?
He didn't even look around, just got down from the old soapbox, took his stuff and walked away. 

Wednesday, May 16, 2012

Latex with Adobe Illustrator

I have been a linux user for a long time but last year I bought a laptop with a digitizer screen and the lack of good results in linux made me switch to Win 7. In the last year, I have learned that a lot of GPL software is ported to Windows and the switch is not painful at all. Problem is that the last update in one of my favorite page editing software: Inkscape has made my figure editing work flow (I never thought I would use this word) stall a little. So, I decided to give Adobe Illustrator a try as CS education is not so expensive. 

Basically, I need to add latex formulas to Illustrator, there's a nice script to do so here. I encountered a minor problem with this script; it seems like page frame is no longer the last element in the pdf compiled by pdflatex. Thus, the formulas generated by the script and imported into Illustrator were lacking the first element and had a full A4page frame. 

The script file is efficiently commented and a quick look into it brought me to Line 66:
for( var i=grp.pageItems[0].pageItems.length-1; --i>=0; )
After a few iterations, I found that the page frame is now the first page item and so the final modified line is:
for( var i=grp.pageItems[0].pageItems.length; --i>=1; )
This fixed my problem and now I have complete latex formulas in Illustrator with just the minimal frame around the object.

I hope this solves your issues too.

Monday, May 14, 2012

Last week papers (20th week of 2012)


From May 6th to 12th, 2012, a complete mess of a week with no time for small talk about the papers. Sorry...

Published
Preprints
  • "Quantum phase transition in the Dicke model with critical and non-critical entanglement" by L. Bakemeier, A. Alvermann and H. Fehske, arXiv: 1204.4974v1 [quant-ph].

Monday, May 7, 2012

Last week papers (19th week of 2012)

It has been an awful busy short week, I can barely keep my eyes open. This week from April 29th to May  5th 2012, I will point out the articles that caught my attention, I'm sorry for the lack of comments...

Published
Preprints

Sunday, May 6, 2012

Last weekend movies (19th week of 2012)


Life has become too busy, I like busy but too busy is really not my kind of thing and it is weird: I enjoy too busy a lot because there's no time to think about stupidities—which are usual when life is not busy at alla—the problem comes when it's too busy that you cannot actually finish one of the 6 things you are working on. Anyway, I have forced myself into the video store, movies and the networks web pages, this came out...
  1. Sherlock Holmes: A game of Shadows, ****
    I enjoyed all of the stories by Sir Arthur Conan Doyle and really lost myself thinking that Holmes died in Switzerland even though there was a third of the book left. Now, I just hope movies Holmes comes back as magazine Holmes came in the past.

  2. Carnage, ***
    Polanski's take on Le Dieu du Carnage, I wish I had seen this on theater. Two couples of parents devolve from civilized sophisticated person into prejudiced childish asses. It has beautiful takes involving a mirror in the set, I loved them.

  3. Underworld Awakening, ***
    I remember I got very excited for the first one nine years ago and, now, I'm far from excited as it seems there's gonna be a fifth one in the series as the ending of this leaves the door open to follow the search for Michael. Oh, most probably I will go to the movies and watch the new one if they make it.

  4. Young Adult, ***
    This is a sad sad comedy. I'm really hoping this is a satire and the third star is just because I still believe in people and this has to be a satire if we are gonna survive as a something close to a rational race.

  5. Mission Impossible: Ghost Protocol, **
    Probably the best of the Mission Impossible series.

  6. Contraband, **
    I love movies about cons, that's why this has the second star.

  7. The Darkest Hour,  
    This film could have been awesome. The story is just terrific, good old war of the worlds invasion and funky aliens but, why o' why, had it to degenerate into a teen movie? 
End of season is almost here and I finally managed to catch up with the series I'm following. Any suggestions for the in-between season?
  1. Last Man Standing S01-E19-23, ****
    Still fun to watch the angry man!

  2. Castle S04-E17-22, ****
    It seems like we are gonna get a change in the episode formula sometime soon!

  3. Hawaii Five O S02-E15, ***
    I can keep on with this, there's no big changes or twist but the crossover with NCIS: Los Angeles was a refreshing thing.

  4. Big Bang Theory S05-E19-23, ***
    It has gotten a second air but not enough to recover the lost star.

  5. Once upon a time S01-E14-20, **
    It has become too slow, please do something!.  
I think I'm gonna go sci-fi and animation for the summer break. 

Monday, April 30, 2012

Last week papers (18th week of 2012)


From 22 to 28 of April 2012, well it was really from 22 to 26 as I took a long weekend off the office...

Published
  • "Quantum Computing with Incoherent Resources and Quantum Jumps" by  M. F. Santos et. al., Physical Review Letters 108, 170501 (2012).

    So, let us say that you have logarithmic spare time and want to make nature do computation for you. Well, Marcelo and coauthors have just show that, in principle, you just need time, patience, clickers and a way to put/remove them clickers from your open system. 

  • "Optical Forces and Torques in Nonuniform Beams of Light" by D. B. Ruffner and David G. Grier, Physical Review Letters 108,  173602 (2012).

    I don't remember seeing an optical tweezer paper in PRL. The authors analyze linear and angular momentum densities of light beams to show how amplitude, phase and polarization profiles contribute to optical forces. One interesting thing they found is how the curl of the spin angular momentum can exert torque on objects without contributing to the orbital angular momentum of the beam. 

  • "Equilibrium and disorder-induced behavior in quantum light–matter systems" by E. Mascarenhas et. al., New Journal of Physics 14,  043033 (2012).

    Coupled two-level system cavity arrays in the polaritonic regime have been proposed to realize the Bose-Hubbard model and Insulator-Superfluid transition  in the past. Now, by using a mean field approach the authors study the effects of disorder on the phases of the Jaynes-Cummings-Hubbard model and find glassy phases using entanglement measures. Interesting, ain't it?  
Preprints
  • "Supermodes of Hexagonal Lattice Waveguide Arrays" by J. S. Brownless et. al., arXiv: 1204.4974v1 [quant-ph].

    A modal approach to hexagonal  photonic waveguide arrays. I'm still trying to follow it and get their results and see if it helps me solve some other waveguide lattices.

  • "Relating the quantum mechanics of discrete systems
    to standard canonical quantum mechanics" by G. Hooft , arXiv: 1204.4926v1 [quant-ph].

    So, imagine you are working near the Planck scale and you want to see if there's something happening there, most probably you want to go from continuous to discrete modelling of the system. Well, here's an approach focused on applications to the harmonic oscillator. I need time to sit down and follow this, discrete dynamics is always interesting for me.

  • "Dynamical scattering models in optomechanics: Going beyond the `coupled cavities' model" by A. Xuereb and P. Domokos  , arXiv: 1204.5301v1 [quant-ph].

    An analysis of membrane-coupled cavities from first principles. In short, we are safe using the coupled-cavities simplification if the coupling element reflectivity is not way below 50% .

  • "Morse potential derived from first principles" by R. Costa Filho et. al., arXiv: 1204.5931v1 [quant-ph].

    I .

Monday, April 23, 2012

Last week papers (17th week of 2012)

Without further ado...

Published
  • "Quantum phase transition in the Dicke model with critical and noncritical entanglement" by  L. Bakemeier, A. Alvermann and H. Fehske, Physical Review A 85, 043821 (2012).

    A phase transition analysis on the Dicke model exploring the behavior of the system when the frequency of the field mode tends to zero, called the classical oscillator limit by the authors, where the model goes to a Lipkin-Meshkov-Glick model. Why people don't cite us? Really... 
  • "Ginzburg-Landau theory for the Jaynes-Cummings-Hubbard model" by Christian Nietner and Axel Pelster, Physical Review A 85,  043831 (2012).

    As  you know, I like anything Jaynes-Cummings or Dicke. A while ago some people decided to study what happens when you couple cQED building blocks (cavities with an atom inside) and used a polaritonic approach to the problem to describe an isulator and superfluid phase of the system. So, it is nice that a phenomenological theory of superconductivity is used to describe the superfluid phase of the system! 
Preprints
  • "Non-Markovian quantum dynamics and classical chaos" by I. Garcia-Mata, C. Pineda and D. Wisniacki, arXiv: 1204.3614v1 [quant-ph].

    The authors study a system coupled to an environment with different levels of chaos and analyse how well a chaotic environment models Markovian evolution.

  • "Theory of optomechanics: Oscillator- eld model of moving mirrors" by C.R. Galley, R.O. Benhunin and B.L. Hu, arXiv: 1204.2569v1 [quant-ph].


    A nice theory of coupling between a field and a moving mirror from first principles that converges to models used in the literature. I was more interested in the convergence to what they called the N x coupling that we widely use in Quantum Optics.

  • "Superradiant quantum phase transition in a circuit QED system: a revisit from a fully microscopic point of view" by D.Z. Xu, Y.B. Gao and C.P. Sun, arXiv: 1204.2602v1 [quant-ph].

    The authors derive the Dicke Hamiltonian from a microscopic model circuit-QED involving superconducting qubits and a quantized field. These model allows for a so-called superradiant phase transition in contrast to a previous analysis in the literature.

  • "Exact solution to the quantum Rabi model within Bogoliubov operators" by Q.H. Chen, C. Wang and K.L. Wang, arXiv: 1204.3668v1 [quant-ph].

    It is a nice step by step demonstration of how to get a exact solution for the quantum Rabi model with an additional tunneling. The authors recover Braak's solution. I personally love the closing paragraph.

Thursday, April 19, 2012

The Russian Solution to the quantum Rabi Model

There's a frightful phrase in physics that goes "a Russian solved it a while ago."

A while ago a very nice paper of D. Braak appeared discussing the integrability of the quantum Rabi Model in Physical Review Letters. This is a nice elegant paper using a discrete symmetry to show that the model is  integrable and gives an exact spectrum for the model [Phys. Rev. Lett. 107, 100401 (2011)].  

The one interesting thing is that the spectrum for the quantum Rabi model was shown by É. A. Tur by resolvent theory eleven years before [Optics and Srectoscopy 89, 574-588 (2000) (English) Optika i Spektroskopiya 89, 628-642 (2000) (Russian)]. If someone can find a pdf file please email it to me, I could only get a bad scan of a battered photocopy.

And don't get me wrong, Braak's paper contribution goes beyond the spectrum. He explores the implications that symmetries has on integrability for models that doesn't have a classical limit/analogue.

Also, a little bit further in time, J. Casanova et. al. analyzed the spectra and dynamics of the quantum Rabi model in the deep strong coupling regime [Phys. Rev. Lett. 105, 263603 (2010)] and presented an approximated spectra for the model and the curious collapse and full revival of the ground state of the positive parity chain.

Again, that particular oscillatory behavior for the same state was discussed by É. A. Tur but for weak coupling in [Optics and Spectoscopy 89, 574-588 (2000) (English) Optika i Spektroskopiya 89, 628-642 (2000) (Russian)] and an elegant approximation to the spectra leading to their result in [arXiv: 0211055 [math-ph]].

And don't get me wrong again, Casanova et. al. study the deep ultrastrong coupling and delve in the analysis they are presenting by adding a phase space analysis and some numerical analysis on the topic.

My point is that some of the results in both Physical Review Letters has been known for ten years already and nobody cited the work of É. A. Tur. A simple Google search of "Jaynes-Cummings model  without rotating wave approximation" brings Tur's paper in the second place, did the editors or reviewers even bother?

Now, surely there's a dozen papers in the review queue that are working on the topic and citing Braak and Casanova—which is the right honest thing to do—but is someone citing Tur? Show the guy some love, his work is nice, clean and elegant.


Edit: I forgot to mention that Tur's result was for weak coupling, g=0.5.



Monday, April 16, 2012

Last week papers (16th week 2012)

Now, Happy belated easter; writing in advance is really confusing because today is the first week of Easter and this will not see light until the second... and I'm rambling... back to business, the interesting things on the physics 'tubes from April 9th to 15th...

Published
  • "Tavis-Cummings model beyond the rotating wave approximation: Quasidegenerate qubits" by S. Agarwal, S.M. Hashemi Rafsanjani and J. H. Eberly , Physical Review A 85,  043815 (2012).

    As Rabi model has come back, it was not long before the many two-level system version should appear back in press. Here the dynamics in a particular regime where the energy gap of the two-level system  is way smaller than the frequency of the field is explored with strong coupling via an adiabatic approximation known for the same regime but for a single two-level system interacting with a field.
Preprints
  • "Can free will emerge from determinism in quantum theory?" by G. Brassard and P. Raymond-Robichaud et. al., arXiv: 1204.2128v1 [quant-ph].

    They push a deterministic, local and realistic interpretation of quantum mechanics, this never gets old at all and now we have a "parallel lives" added to the zoo of interpretations. If you like interpretations, philosophical speculation and so, this is for you  

  • "Producing and measuring entanglement between two beams of microwave light" by E. Flurin et. al., arXiv: 1204.0732v1 [quant-ph].

    I'm too lazy to read it today but entanglement between beams of microwave is interesting. 

  • "Thermal phase transitions for Dicke-type models in the ultra-strong coupling limit" by M. Aparicio Alcalde et. al., arXiv: 1204.2271v1 [quant-ph].

    I like almost everything related to Dicke model, here a study of thermal phase transitions of the mathematical model is presented. I like papers involving Emary and Brandes, they are nice reads.

Monday, April 9, 2012

Last week papers (15th week 2012)...


I told you about the Nature Physics Insight on Quantum Simulation, so I will skip those 

Published
  • "Ultra-high Q mechanical oscillators through optical trapping" by  D. E. Chang,  et. al., New Journal of Physics 14, 045002(2012).

    This is interesting: Reaching the quantum ground state of a mechanical oscillator at room temperature.The authors propose the use of optical forces to free a the characteristics of a mechanical structure from its material properties.
      
  • "Widely Tunable, Nondegenerate Three-Wave Mixing Microwave Device Operating
    near the Quantum Limit" by N. Roch et. al., Physical Review Letters 108, 147701 (2012).

    Now, the best for the last. I find this awesome, people are making better and better microwave resonators, emitters and now it is possible to do three-wave mixing in the microwave regime!

Preprints
  • "Entanglement control in hybrid optomechanical systems" by B. Rogers et. al., arXiv: 1204.0780v1 [quant-ph].

    I'm too lazy to read it today but seems quite interesting...  

  • "Producing and measuring entanglement between two beams of microwave light" by E. Flurin et. al., arXiv: 1204.0732v1 [quant-ph].

    I'm too lazy to read it today but entanglement between beams of microwave is interesting. 

Tuesday, April 3, 2012

Fear...

Fear is an emotion caused by a perceived threat (real or imaginary).

Fear is a kind of survival mechanism, an automatic response that prepares mind and body for the unknown; a really bad unknown. 

Fear, reigned, may lead to acts beyond our idea of human capabilities or, unreigned, to crushing anxiety crippling life at the innermost sanctuary of the mind. 

I had never felt fear living in Mexico. Now I do and I'm not even in my homeland. No more than five years ago, the sight of a random guy walking aimlessly the parking lot during the wee hours just made me think of a dude smoking a cigarette or waiting for his friends to keep the party on; now, it kept me looking through the window for the half hour the dude was there, searching for security's phone in the emergency sheet at the door and wondering where the fuck was the security guard whose snoring bothered me all the nights before that night. 

I never thought I would get to that. I never thought I would stop taking the overnight bus home to visit mom or giving up driving uncountable hours by day or night during vacations. I gave those up no more than five years ago. 

I know what it is to live a normal life with normal fears and that's either in the so far untouched center of Mexico (Puebla and Queretaro seem to be the less conflictive) or far from this beautiful country. Sad but true.

Fuck fear!

Monday, April 2, 2012

It's Quantum Simulation issue in Nature Physics Insight!

I can tell you that this is one of  Feynman's most beautiful phrase and I use it as often as possible in my presentations as opening slide:

 “Nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum mechanical, and by golly it's a wonderful problem, because it doesn't look so easy.”
That's the opening phrase for Trabesinger's editorial on the current issue of Nature Physics that includes a commentary by Cirac and Zoleer and reviews by Bloch, Dalibard & Nascimbéne, Blatt & Ross, Aspuru-Guzik & Walther, and Houck, Tureci and Koch.

Enjoy! I know I will...

Last Week Papers (14th week 2012)

It feels good to be back in an office and able to follow the literature. I'm thinking that I like the list format and now will split it in two: published and pre-prints because it is good to talk about pre-prints.

Published

  • "Quantum Interface between an Electrical Circuit and a Single Atom" by  D. Kielpinski,  et. al., Physical Review Letters 108, 130504 (2012)

    They have shown it may be possible to couple an ion to a quantized current from a superconducting circuit. That's nice as the experiments in classical coupling of currents and ions can be used to build upon them and get to this. Interesting read.
  • "Optical Detection of the Quantization of Collective Atomic Motion" by N. Brahams et. al., Physical Review Letters 108, 133601 (2012).

    They are measuring the collective motion of a gas coupled to a cavity field. That impresses me.

  • "Superradiance in spin- j particles: Effects of multiple levels" by G._D Lin and S. F. Yelin, Physical Review A 85, 033831 (2012).

    It has always been a problem to talk about superradiance in two-level systems. Physically sound models with two-level systems involve Raman pumping to auxiliary levels in 4-levels schemes. It has always been mentioned that it may be possible to have superradiance with multi-level atoms. Well, they calculate it and show the effect of multi-level atoms in radiance, decay and so on...

  • " A heuristic approach to BEC self-trapping  in double wells beyond the mean field" by K. Rapedius,  Journal of Physics B: Atomic, Molecular and Optical Physics 45, 085303 (2012).

  • A semi-classical analysis of the Bose-Hubbard dimer Hamiltonian with some curious variations that seem to help producing some approximations that may be valid in the mean-field and finite particle number cases.
      
  • "Effects of orbital angular momentum on the geometric spin Hall effect of light" by L.-J. Kong, Physical Review Letters 85, 035804(2012).

    Reading it and trying to figure it out... I have never read about the spin Hall effect of light and it seems like there are two different kinds: one at a gradient refractive index interface and another that is geometric and relates to observation from a frame tilted with respect to the propagation direction. I need to read more about all this things.

Preprints
  • "Exact real-time dynamics of the quantum Rabi model" by F.A. Wolf, M. Kollar, and D. Braak, arXiv: 1203.6039v1 [quant-ph].

    Last year Braak wrote a very nice PRL where he presented the proper system of Rabi model; now, this follow-up paper builds upon the basis presented before and analyses the dynamical behavior in different time regimes. I wonder why nobody cites E. A. Tur's papers on approximations to the eigenvalues of Rabi model. Anyway,  This manuscript is quite interesting and a must read if you work in Quantum Optics.  

  • "Quantum thermometry using the ac Stark shift within the Rabi model" by K.D.B. Higgins, B.W. Lovett, and E.M. Gauger, arXiv: 1203.5994v1 [quant-ph].

    I have the feeling that whenever I get to grasp what they are doing I'm gonna like it.

Monday, March 26, 2012

Last Week Papers (13th week 2012)

I'm back from vacations and trying to catch up with the quantum optics pile of papers that came out in those two weeks. Here're some of the articles that caught my eye:
  • "An analysis of the changes in ability and knowledge of students taking A-level physics and mathematics over a 35 year period" by Peter J Barham, Physics Education 47, 162-168 (2012).

    I loved the closing phrase, I cite: "The change in mathematical ability makes teaching physics at degree level more challenging, but that is a challenge we should embrace, rather than simply protest about."

  • "Extracting Dynamical Equations from Experimental Data is NP Hard" by Toby S. Cubitt, Jens Eisert, and Michael M. Wolf, Physical Review Letters 108, 120503 (2012).

    In other words, it is damn hard to figure out the underlying math just from experimental data. The result is nice to read and quite interesting.

  • "Cooling by Heating: Refrigeration Powered by Photons" by B. Cleuren, B. Rutten, and C. Van den Broeck, Physical Review Letters 108, 120603 (2012).

    This is interesting, you can cool a lead by joining it to another lead through two quantum dots. There was another interesting paper in the same issue about cooling with incoherent light but I seem to have misplaced it on my files.

  • "Generation of Mesoscopic Entangled States in a Cavity Coupled to an Atomic Ensemble" by G. Nikoghosyan, M. J. Hartmann, and M. B. Plenio, Physical Review Letters 108, 123603 (2012).

    Something like dark states but by using 6-level atoms.

  • "Controlled Dicke Subradiance from a Large Cloud of Two-Level Systems" by Tom Bienaime, Nicola Piovella, and Robin Kaiser, Physical Review Letters 108, 123602 (2012).

    Everybody was talking about Dicke super-radiance two years ago, now it is time for Dicke subradiance to be shown experimentally and used to control storage in long-lived subradiant modes