Physics and Physicists: Fringe Physics

Physics and Physicists: Fringe Physics

Vitrification vs. Crystalization

The most basic difference between the glass forming (vitrification) process and the crystallization may be seen in the figure on the left. Vitrification is actually not really a transition , because it does not involve any genuinely singular behaviors, in contrast with crystallization. A very likely implication is that, vitrification should not be due to a critical mode that features long-range correlations. Its dynamics should be essentially local, like what happens to a traffic congestion.

Casimir force between two sheets of graphene

I had thought about this sometime ago but did not come up with the calculations on this problem, basically i did not get time to do that. Now i'm glad that some people have done this. See the following:
1. http://prb.aps.org/abstract/PRB/v80/i24/e245406
2. http://prb.aps.org/abstract/PRB/v82/i15/e155459
3. http://benasque.org/2011qfext/talks_contr/2021_Sernelius.pdf
4.http://arxiv.org/abs/1102.1757

Supersolid in history

Supersolid has been a fascinating conception since its inception. However, the experimental aspects are still not conclusive, as reviewed by Thouless in his private note:
http://www.phys.washington.edu/users/thouless/INItalk0808.pdf

ACCP

This website collects plenty of information of American scientists who have been working in US since 1945 to present. http://www.aip.org/history/acap/

How SSC came into being

Here is an article accounting the history of Solid State Communications. I'm interested in such stuff basically because I'm concerned with how should a practicing scientist regard the platforms fostering their communications.

Physics and Physicists: Higgs Boson Latest Update

Physics and Physicists: Higgs Boson Latest Update

Edge states in graphene

Graphene offers more [http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.107.236806]:

In condensed matter systems, topology often gives rise to gapless excitations at the edge (in 2D) or the surface (in 3D). Such excitations in the 2D fractional quantum Hall state should manifest in the edge behaving as a Luttinger liquid, in which tunneling is determined by a universal power law related to an attribute—the filling factor—of the magnetic flux through, and the number of electrons in, the 2D state.

However, no such behavior has yet been observed at the edges of 2D semiconductor heterostructures, the most-studied quantum Hall systems. Theorists say that in these systems the conflicting interplay between the confinement potential, attracting each electron towards the center, and the Coulomb force, pushing them apart from each other, modifies the edge itself. This process—edge reconstruction—disturbs the universal Luttinger liquid picture in the experimentally accessible distance scales.

In a paper in Physical Review Letters, Zi-Xiang Hu, at Princeton University, and his colleagues tell us that we may, after all, be able to see chiral Luttinger behavior in another system in which fractional quantum Hall effect has been observed—graphene. In graphene, electrons are confined by metallic gates that are placed a specific distance away. By contrast, in semiconductors, electrons are confined by dopants. This one difference should make graphene less susceptible to edge reconstruction and reveal the fractional quantum Hall state. The authors say that experimentalists should therefore finally see the elusive universal edge behavior in the experimentally accessible state with filling factor 1/3. – Sami Mitra

A new version of Wheeler's set up

The particle-wave duality seem always under debate and ingenious experiments have been contrived from time to time to violate it. A famous example is the one proposed by John-Wheeler. It is called 'delayed-choice experiment'. In its existing version, a classical switch has been in use. Here comes a new design using quantum switches [http://physics.aps.org/articles/v4/102].

This so-called delayed-choice experiment was performed in 2007 using an interferometer [1]. In the normal setup, a beam splitter creates two separate light beams that later recombine in a second beam splitter. Detectors placed at the two outputs of this beam splitter both register an interference pattern. However, this wave detector can be turned into a particle detector by removing the second beam splitter, so that the two paths no longer interfere. In the experiment, the choice to add or remove the second beam splitter was made after an individual photon had already passed through the first beam splitter. The data showed that particle and wave behavior were unaffected by the delayed choice, as expected from standard quantum mechanics.

Radu Ionicioiu, now at the Institute for Quantum Computing in Waterloo, Canada, and Daniel Terno of Macquarie University in Sydney, Australia, wanted to see what happens in the thought experiment if the delayed choice is made through quantum means. They imagined that the interferometer contains a quantum device—perhaps an atom in a cavity or a micro-mirror placed on a cantilever—that can exist in two possible states. One state selects the particle experiment, and the other selects the wave experiment. This quantum control element can be placed in a combination, or superposition, of its two states, making the whole experiment participate in the wave-particle duality.

“We show you can do both wave and particle experiments at once,” Ionicioiu says. This means the choice of wave vs particle can be delayed indefinitely. The photon can be observed at one of the detectors and still not “know” if it is supposed to be a wave or a particle. It’s only when the observer decides to measure the state of the quantum control that the photon’s behavior can be identified as wavelike or particlelike.

Back now

Just back from thesis writing. It took me really a lot of time. But I think it is worthy. Hope somebody would be interested. In writing the thesis, I have re-examined the work I did and this renders a clearer picture of what has been done. Some provoking stuff can be matter of future research. Now I have to go on to new problems.