Tag: physics

Physics Journals learning from Open Science

It is good to see some of the biggest names in physics journals embrace ideas pioneered by the open sciences community.

I hope they push further! Any comments of future directions you would like them to take?

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Theorem: Consider the set of all sets that have never been considered. Hey! They’re all gone! Oh, well, never mind…

Andy Maloney’s Open Science Biophysics Dissertation

Andy Maloney, a leader in open science, is embracing the open philosophy all the way. He has decided to write his dissertation as it evolves as an open science document. First chapter draft is here. Go there to witness the first fully open dissertation ever.

Yes, every version, every draft, every correction, everything will be posted there. Members of the wiki can also write him comments and suggestions. This is a fantastic idea, as this is the first time others can see how  a dissertations actually develops. This will help both experts in the field, and graduate students that want to see how is the dissertation-writing process.

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[Jesus walks out of the lake with a small bottle of lemonade]
Jesus Christ: Lemonade?
Father Eustace: Will there be enough?
Jesus Christ: Oh, there’ll be plenty.
-Jesus Christ Vampire Hunter

International Journal of Quantum Information Call for Papers: Quantum Correlations: entanglement and beyond

Kavan Modi has asked me to share this call for papers for a special issue. It looks very exciting indeed.

CALL for PAPERS (Special Issue)
INTERNATIONAL JOURNAL of QUANTUM INFORMATION
Quantum Correlations: entanglement and beyond

GUEST EDITORS
Shunlong Luo (Chinese Academy of Sciences, CN)
Sabrina Maniscalco (Heriot-Watt University, Edinburgh, UK)
Kavan Modi (National University of Singapore, SG)
G. Massimo Palma (University of Palermo, IT)
Matteo G. A. Paris (University of Milano, IT)

Quantum correlations have been the subject of intensive studies in the last two decades, mainly due to the general belief that they are fundamental resources for quantum information processing and other
tasks in quantum technology. The first rigorous attempt to address the classification of quantum correlations was put forward by Werner, who formalized the elusive concept of quantum entanglement. More recently, other quantities, as such quantum discord, have been proposed to capture different aspects of the quantumness of correlations. In parallel, several applications where quantum, classical, hybrid correlations play a role have been suggested and implemented. Among them we mention quantum imaging, interferometry, state engineering, computing and entanglement-assisted quantum measurements.

This special issue is aimed to collect papers addressing both fundamental problems and applications, thus offering to readers comprehensive and up-to-date overview on the characterization and use
of quantum correlations.  We welcome papers that address fundamental aspects of quantum and classical correlations in discrete and continuous variable systems, propose implementations to make
quantitative measurements of quantum correlations, or describe experiments that exploit quantum correlations as a resource for quantum technology.

Possible topics include, but are in no way limited to: characterization and measurement of entanglement and quantum discord, discrimination of classical and quantum correlations in quantum systems, applications of quantum correlations to quantum technology, dynamics of quantum correlations in open systems, decoherence, metrology, error correction.

Manuscripts should be submitted to matteo.paris@fisica.unimi.it with subject “[QCSPE] and must meet the normal refereeing standards of IJQI.

LaTeX is the exceedingly preferred format, IJQI macros are available at
http://www.worldscinet.com/style_files/ijqi/187-readme_2e.shtml
Deadline for submission is May 15th 2011. Publication is expected within 2011.

Sincerely,

Kavan Modi, PhD
Centre for Quantum Technologies
National University of Singapore

—
“It is thermodynamics gone mad,” by Lord Kelvin, one of the founders of thermodynamics, commenting on Boltzmann’s derivation of Stefan’s law.

The Voice of God, Zeno and Bohmian Mechanics

A title doesn’t get more philosophical and mystical in a non-philosophical and non-mystical and technical paper than in this one:

Zeno Paradox for Bohmian Trajectories: The Unfolding of the Metatron by Maurice de Gosson, Basil Hiley

Some definitions not provided in the paper that might help unpack the references made in the title:

Metratron – angel in the religions of the Abrahamic tradition, many times depicted as the Voice of God.

Zeno Paradox – philosophical argument for “a watched pot never boils”, a physical phenomena in quantum mechanics.

Bohmian trajectories – a school on the interpretation of quantum mechanics, related to pilot waves theory.

However, I must stress this paper is not about philosophy or angels, it just a clever title.

—
God bless those pagans.
-Homer

Why does the world look classical?

A few days ago we posted a new paper.

General Bound on the Rate of Decoherence [arXiv:10045405]

Cesar A. Rodriguez-Rosario, Gen Kimura, Hideki Imai, Alan Aspuru-Guzik

We establish the necessary and sufficient conditions for a quantum system to be stable under any general system-environment interaction. Quantum systems are stable when the time-derivative of their purity is zero. This stability provides a dynamical explanation of the classicality of measurement apparatus. We also propose a protocol to detect global quantum correlations using only local dynamical information. We show how quantum correlations to the environment provide bounds to the purity rate, which in turn can be used to estimate dissipation rates for general non-Markovian open quantum systems.

[SciRate]

The paper could have been alternatively titled: “Necessary and Sufficient Conditions for System Stability Under Any Coupling to the Environment”. In this post, I want to discuss briefly our first result of the paper:

$$left[ frac{d}{dt}mathbf{P}^mathcal{S}_tright]_{t=tau} = 0; Leftrightarrow ; left[rho^mathcal{S}_tauotimes I^mathcal{E},rho^mathcal{SE}_tauright] =0$$.

We were interested in finding universal decoherence stability criteria that depended on the structure of the system-environment state, but was independent of the particular Hamiltonian dynamics. We focused on the measure of decoherence called “Purity”, in particular the rate of change of purity. We found that there exist system-environment states that preserve the purity of the system independent of the details of the interaction Hamiltonian. These states are given by the commutator in the equation above vanishing, and we call them “Stable System States” or SSS for lack of a better name.

SSS states are sparse topologically and not-dense: they are quite rare. But, at the same time, they include states whose system part looks very classical. On first sight, since they are rare, this would raise the question of why does the world looks classical to us. However, the equation above also implies that these states are stable under decoherence, and thus can be long-lived.

In other words, we can prove how classical states emerge naturally in the world without any assumptions of the dynamics! This provides a non-equilibrium thermodynamical explanation to why our universe looks classical.

Reuters Interviews Daniel Lidar

Reuter’s ScienceWatch recently posted an interview with Prof. Daniel Lidar from USC where they discuss Daniel’s most important papers, focusing on decoherence free subspaces. Daniel was very kind to mention my own work on Open Quantum Systems with initial correlations during the interview.

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“The theory of its operation is rudimentary and attempts to improve its performance are still made in an almost haphazard way”
-Sadi Carnot on engines

APS March Meeting, in the City of Roses

I spent last week in Portland for the APS March meeting. It was one of my favorite APS meetings so far. First, the city has some free public transportation, is walkable, and very fun. I got to see many old friends. And I ended up giving two talks.

The first talk was on our PRL paper Time-Dependent Density Functional Theory for Open Quantum Systems with Unitary Propagation.

The session was very interesting, with many proposals for how to expand the realm of applicability of TD-DFT. My boss was supposed to give this talk, but ended up canceling his trip at the last minute.

The second talk was on our paper Linear assignment maps for correlated system-environment states.

This talk was part of the OQS and Decoherence session. For some reason, this session is always on Friday afternoon, which is always the least attended day at the APS, as many leave the conference early. Can this be changed? Still, I got all the usual questions about negative maps, so people were somewhat interested.

How are the sessions organized? How are the days chosen, how are the talks in the session organized? I don’t know. Hopefully, next year, my talk will be at a reasonable day and time.

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At dawn of day, when you dislike being called, have this thought ready: “I am called to man’s labour; why then do I make a difficulty if I am going out to do what I was born to do and what I was brought into the world for? Is it for this that I am fashioned, to lie in bedclothes and keep myself warm?”  “But this is more pleasant.”  “Were you born then to please yourself; in fact for feeling, not for action? Can’t you see the plants, the birds, the ants, the spiders, the bees each doing his own work, helping for their part to adjust a world? And then you refuse to do a man’s office and don’t make haste to do what is according to your own nature.” “But a man needs rest as well.”
-Marcus Aurelius’ Meditations, on how hard it is for a roman emperor to get up in the morning