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A new quantum framework that blurs cause-and-effect at a fundamental level could improve information processing and lead to a theory of quantum gravity.

Discord in the Quantum World
An alternative quantum resource to entanglement could help physicists in the quest to construct a quantum computer.

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Thinking of causation as a "two-way street"—along which the passage of information can be inverted—could have implications for the origin of life.

FQXi BLOGS
December 6, 2013

New Blog Entries

Somnium, Solaris and Making a Glass Universe
By ZEEYA MERALI • Oct. 31, 2013 @ 19:06 GMT

 Credit: Natalie Kay-Thatcher
It's not every day that I can claim to have created the universe--or helped to, at least. But a couple of weeks ago I attended a workshop led by Simone Kay to build an image of the cosmos using stained glass. The glass appliqué panel is now on display at THE CUBE in London, where artist-in-residence Natalie Kay-Thatcher, who organized the workshop, is running a series of space-themed events.

You may recognize Natalie's name; last year, she organized the Jiggling Atoms exhibition. Now, she is producing a series of pieces inspired by two texts, Somnium, by astronomer Johannes Kepler, and Solaris by Polish writer, Stanislaw Lem.

 Credit: Natalie Kay-Thatcher
To my shame, I have to admit that I have not read Kepler's Somnium, which describes a trip to the Moon, complete with demons. It is has been called both the first science-fiction novel and the first serious scientific treatise on lunar astronomy (minus the demons). The B&W image, right, is one of Natalie’s illustrations inspired by Kepler's imaginings.

Solaris provides a different challenge for an artist, since it involves an ocean planet that defies understanding by the human mind. I’m currently reading Solaris and I’ll keep you posted on how Natalie deals with the portraying the incomprehensible. But if you’re based in London, I encourage you to visit her exhibition, in person, which is growing day by day, and see for yourself. You can also enrol in one of her workshops (which run into December) or attend one the forthcoming talks by artists and scientists.

 Credit: Natalie Kay-Thatcher
I should also list the other contributors to the panel at the top and to the right (who probably all did far more than me): Laura Doehler, Ellie Stamp, Rob Heppell, Matt Cullin, Tim Bell, Ray Goodall and, of course, Simone Kay and Natalie Kay-Thatcher.

It From Bit, or Bit From It: Results
By BRENDAN FOSTER • Oct. 31, 2013 @ 16:17 GMT

And Now! I am pleased to announce the winners of our 2013 Essay Contest, "It From Bit, or Bit From It?"

The contest theme this year took its inspiration from an idea of John Wheeler, asking whether It came from Bit? Some of our entries of course tried to answer that question directly, but I was happy to see that many entries took on the stickier job of trying to understand just what Wheeler meant with that question. Did he mean, does the actual universe emerge as an evolving answer to a series of yes/no questions? Or did he just mean, do all physical laws reduce to binary computations? Or does the question not make any sense at all?

I must also credit another inspiration for this year's contest: an entry from Julian Barbour into our 2011 contest Digital or Analog. Julian's essay, "Bit From It", anticipated our theme by challenging Wheeler's concept, with the assertion that "things, not information, are primary".

Now, let's get to the winners:

First prize of $10,000 goes to ... Matt Leifer, for his essay ""It from bit" and the quantum probability rule". Matt is an independent researcher with a specialty in quantum foundations. His essay presents options for answering the essay question either way, and then argues that the options do not conflict with each other. Matt writes (excellently) about these and related issues on his blog. Our Second Prize winners, who both receive$5,000, come from contest regulars...

Carlo Rovelli, for "Relative information at the foundation of physics",

and the team of Angelo Bassi, Saikat Ghosh, and Tejinder Singh, for "Information and the foundations of quantum theory".

A further five essays received Third Prize, receiving $2,000 each (and a Membership invitation where applicable), and ten other essays received Fourth Prize and$1,000. Visit this link to view the full list of winners.

I am also happy to announce that we have two Special Commendation Prizes to award this year. These prizes are chosen by our panel of experts to award "non-professional and/or non-academic" entrants, and come with a cash award of \$1,000 each. (I need to emphasize that the panel is not able to evaluate all the entries in our contest, so these prizes do not mean that the panel necessarily ranked these entries above all others in terms of overall score. The panel did, though, find them to be good reads and worthy of commendation.)

This year, the panel chose to highlight a pair of student entries, commending them for the attempt to grapple with foundational questions.

Congratulations go to:

Jennifer Nielsen, for "Is Bit It?"

and

Xiong Wang, for "Bit: from Breaking symmetry of it".

On behalf of all the FQXi administration, I want to thank our cosponsers The Peter & Patricia Gruber Foundation and the John Templeton Foundation for making the contest possible. I also want to thank our media partner Scientific American for helping us put it all together and getting the word out.

And finally, all of us at FQXi want to say thank you to everyone who participated, including the authors of all entries, and everyone who stopped by the forums to read and discuss.

Here's to the next contest!

Fighting Noise with Noise: Simulation of motional averaging with a superconducting circuit
By GHEORGHE SORIN PARAOANU • Oct. 31, 2013 @ 15:59 GMT

...Imagine it is deep winter in Finland, where I am based at Aalto University, and the temperature outside is -30 degrees Celsius. A nicely warmed sauna at 80 degrees Celsius would surely be welcome for warming up. Getting in the sauna, then directly out in the freezing cold is an "extreme" experience that many people actually enjoy a lot. If you are one of those, and assuming that you spend roughly the same amount of time outside in the cold and in the sauna, the average temperature you see is a perfect 25 degrees Celsius. Welcome to sunny California! Well, not really...

Yet, as it turns out, switching between states with different chemical potential is something that particles in various many-body ensembles experience, and indeed this phenomenon has been seen before in NMR (nuclear magnetic resonance). An experiment recently carried out by our group at Aalto (with theory support from Oulu University) looking into this effect shows that it could have relevance for quantum computation. Quantum computers process information encoded onto "qubits" (or "quantum bits"). For example, the polarization state of photons is typically used in quantum-optics experiments. In our case, we employ the oscillatory states of an electrical circuit, realized with Josephson junctions and superconductors. The quantum bits can not only exist in one or the other of two states (like binary digits 0 and 1), but also as a superposition of both states simultaneously--allowing, in theory, for much more powerful processing.

In our experiment we simulate the effect of switching the chemical potential using a circuit comprising a qubit and a measuring cavity by changing the qubit frequency between two distinct values (J.Li et. al., Nat. Commun. 4, 1420 (2013)). We keep track of this frequency by monitoring the interaction between microwave radiation and the qubit, which results in distinctive lines in the absorption spectrum at certain frequencies.

 Motional averaging under a random modulation
Now, you might expect that we would see two spectral lines, one corresponding to each of the frequency extremes--in much the same way as our Finnish sauna fan would register two very different temperatures if he or she jumped from the sauna to the snow. That is indeed what we saw when the switching was done slowly. But surprisingly, when the change was faster than a critical value (the inverse of the qubit frequency separation) the two lines merge into a single one. The image on the right shows motional averaging under a random modulation (pulse pattern in white). The figure presents the spectrum (horizontal axis is frequency) at increasing jump frequencies (vertical axis).

The effect can be interpreted as meaning that our ability of distinguishing between the two values of the qubit frequency is impaired by the fast switching. Indeed, the single (motional-averaged) spectral line is formed precisely when the jumping rate exceeds the bound set by the time-energy uncertainty relation,

${\Delta} t {\sim} {\frac{\hbar}{\Delta E}}$

Why is this important? One of the biggest hurdles to building a quantum computer is that the quantum effects on which it relies are fragile and can easily be destroyed by decoherence, as the qubits cannot be totally isolated. The motional averaging experiment suggest a new route to improving the decoherence times of the existing qubits. If the noise entering from the environment in such a device fluctuates slowly, it will have a disruptive effect, for example displacing the frequency of the qubit between two extremes. But if this noise can be made faster than a threshold value, the qubit will effectively be at one stable frequency, reducing the so-called dephasing rate. Paradoxically, one can fight noise with even more noise! Indeed, the group has demonstrated that the motional-averaged line preserves the quantum coherence of the original qubit and elementary quantum operations can be performed.

So how fast one has to jump in and out of the sauna to experience a perfect 25 Celsius? According to the calculations in our paper, you have to jump, on average, more than roughly 10 thousand billion times per second!

--

Gheorghe Sorin Paraoanu is a physicist at Aalto University and a member of FQXi.

Particle Physics and Art in Superposition
By ZEEYA MERALI • Oct. 8, 2013 @ 00:42 GMT

 Covariance
Later today (or tomorrow depending on where you are based), the winner(s) of the Nobel Prize for Physics will be announced. At the time that I am writing this, the hot favorites are some combination of the theoretical physicists who predicted the Higgs mechanism. (Gerry Guralnik blogs for us about his role in the prediction.) Many are also calling for the ATLAS and CMS collaborations to be recognized for the discovery of the Higgs boson at the Large Hadron Collider (LHC), the underground accelerator that is so vast it crosses the border between Switzerland and France.

This brings to mind a question posed by artist Lyndall Phelps, whom I met a few weeks ago at the launch of her particle-physics inspired exhibition, Covariance, open now at the London Canal Museum. Phelps pondered what our descendants would make of these huge subterranean structures, if they stumbled onto them during an archeological dig. Whether or not they would fathom the purpose of such detectors, they will surely be struck by their beauty. On one of my visits to the LHC, CERN's research director, Sergio Bertolucci urged me to visit the underground heart of the accelerator before the detectors were finally closed off for data-taking, describing the experience of first encountering the machinery as "magnificent, like standing within a cathedral."

Bertolucci's promise was more than fulfilled when I saw the detectors. So I would not have envied Phelps the task she was appointed some months ago by the UK's Institute of Physics: to create a piece of art that evokes the majesty of such large-scale particle physics experiments. In collaboration with Ben Still, a particle physicist at Queen Mary, University of London (and an FQXi blogger and frequent podcast contributor), Phelps designed and built the Covariance installation (image, top right). The artwork is inspired by the Superkamiokande neutrino observatory in Japan, where Still works. It is a huge and impressive piece, made up of 1 km of brass rods, 28,000 glass beads, hundreds of acrylic discs and 36,000 diamantes. The installation is suspended in the circular brick space--about 30 feet in diameter--of a Victorian ice well.

 Superkamiokande
I spoke with both Phelps and Still for this month's podcast. You can hear them discuss the themes that they hoped to bring out with the piece. The most obvious note that strikes you when you first see it is the rotational symmetry that mimics the structure of particle physics detectors (Superkamiokande image, right), along with the vibrant colours seen at the LHC, for instance, and in data from particle physics experiments. The underground location is also key to the power of the artwork. It not only captures the fact that such detectors are located below ground, but it creates a dark, quiet, contemplative space in which to experience the work.

Perhaps the most fascinating and unexpected aspect is Phelps decision to pay tribute to the female "computers"--the women who historically recorded data from bubble chambers--with her choice of materials and her technique for building the installation. Since Phelps and Still can express their aims better than I can, I shall let you listen to them on the podcast, where you can also hear more of my thoughts on the exhibit.

Covariance is the first artwork in the "Superposition" series of art-physics conversations initiated by the IOP. It is still open for viewing and, if you are near London, I heartily recommend you go along. Booking information is available on the blog that accompanies the installation.

 Covariance up close

From Particle Physics to Ice, Water and Steam
By BEN STILL • Oct. 1, 2013 @ 13:57 GMT

 Image credit: Craig Ratcliffe
A mathematical method that determined an elementary link between two forces of nature has also led to a deeper understanding of what seems to be a fundamental link between solids, liquids and gases. The work is described in Scientific Reports 3, 2794 (2013) (http://arxiv.org/abs/1306.1892).

A process know as symmetry breaking is key to the theory of how the recently discovered Higgs boson gives mass to the fundamental building blocks and force carrying particles of nature. The mathematical procedure also shows, however, that there is an underlying connection between the electromagnetic force, responsible for chemistry and electricity, and the weak nuclear force, responsible for the processes making the Sun shine and radioactivity. Dima Bolmatov et al. at Queen Mary, University of London have now taken this idea out of the realm of particles and into the world of condensed matter physics.

In searching for an analytical approach to understanding the properties of liquids Dima Bolmatov and Kostya Trachenko have taken a different route to most. Most of their peers have sought to explain liquids as more heavily interacting gases but Bolmatov and Trachenko have looked at explaining liquids as solids that have more freedom. The research, titled the "phonon theory of liquids", explains how liquid properties are derived from solids with less restrictions on their relative movement. Bolmatov describes it as "cutting springs" which constrain the movement of individual atoms in a lattice.

Now an extension to this idea points to an underlying connection that allows all three states of matter and the transitions between them to be explained in one theory.

Breaking a symmetry

A symmetry is any series of manipulations that takes some object and ends up with the same object. For example one can take a picture of a square on a page and rotate it 90o to return to an identical square. You could also reflect the image of the square in a mirror and see an identical square. These rotational and reflection symmetries are individual manipulations but even if we combined them they too would also be a symmetry.

A circle has an infinite rotational symmetry; no matter by how much or how many times you rotate a circle you always end up with an identical circle at the end. What now if we were to draw a straight line from the centre to one point on the circle. No longer can we rotate the circle by any amount and get an identical circle. There is only one orientation in which the circle looks that specific way – the rotational symmetry the circle once had has been broken. We have removed this particular symmetry and in essence taken away what was once a true degree of freedom.

This exact same process is performed within the mathematics of the Higgs mechanism in particle physics. The drawing of a line above is executed in the maths by specifying a preferred direction in space. This in combination with the Higgs field results in particles gaining a mass when at rest.

Broken Symmetry and States of Matter

Dima Bolmatov, Edvard Musaev and Kostya Trachenko of Queen Mary, University of London have now proposed that a new idea using the same procedure can define a unified description of all three states of matter. If one thinks of matter as a solid but with different degrees of freedom then breaking of a symmetry distinguishes its phases (solid, liquid and gas). Although the symmetries themselves are different the process as described follows exactly the same route as the Higgs mechanism.

Mathematically, this was realised by introducing an interacting phonon Hamiltonian with ground state configurations minimising the potential energy. Symmetry breaking SO(3) to SO(2), from the group of rotations in reciprocal space to its subgroup, leads to emergence of energy gaps of transverse excitations. As a consequence of the Goldstone theorem it readily results in the emergence of energy spectra of solid, liquid and gas phases.

Glass transition and critical phenomena are among other challenging problems that can be considered in this framework.

--

Ben Still is a physicist at Queen Mary, University of London.

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Essay Contest 2013: It From Bit, or Bit From It?
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Without further ado, I am happy to announce the start of FQXi's 2013 Essay Contest!

Our new topic:

It From Bit or Bit From It?

The past century in fundamental physics has shown a steady progression away from thinking about...
March 25th, 2013 | 683 comments | view blog entry & comments

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