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

• "Quantum Rabi model for N-state atoms " by  V. Albert, Physical Review Letters 108, 180401 (2012).
  
  
  
  


• "Acoustic analogue of graphene: Observation of Dirac cones in acoustic surface waves" by D. Torrent and J. Sánchez-Dehesa, Physical Review Letters 108,  174301 (2012).
  
  
  
  


• "Encoding relativistic potential dynamics into free evolution" by C. Sabín et. al., Physical Review A 85,  052301 (2012).
  
  
  


• "Super diffusion in optical realizations of Anderson localization" by Y. Krivolapov et. al., New Journal of Physics 14, 043047 (2012).
  
  
  
  


• "Simple derivation of the Lindblad equation" by P. Pearle, European Journal of Physics 33,  805 (2012).
  
  
  
  

Preprints

• "Multipartite optomechanical entanglement from competing nonlinearities " by A. Xuereb et. al., arXiv: 1204.4974v1 [quant-ph].
  
  
  
  

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. 

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 .

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... 

• "Ultimate limits to quantum metrology and the meaning of the Heisenberg limit" by M. Zwierz, C.A. Perez-Delgado and Pieter Kok, Physical Review A 85,  042112 (2012).
  
  
  I remember being at a seminar where Carlos presented this work in CQT. It's a mashup of query complexity with quantum mechanics to reformulate a Heisenberg limit for quantum metrology based on the idea of physical resources. 

• "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.

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.