IPF 2010: Baby phase transition, multilayer graphene, LHC now

Industrial Physics Forum Even though the IPF is devoted to subjects related to research at industrial labs—and to lasers in particular in this 50th anniversary year of the laser—each meeting also features a slate of speakers who can hold forth on the hottest topics regardless of their affiliation.

Baby phase transition

One of this year’s frontier speakers was Chris Monroe of the University of Maryland and the Joint Quantum Institute . He is trying to implement Richard Feynman’s forecast, made in his famous 1959 essay “There’s Plenty of Room at the Bottom,” of information systems based on the manipulation of small numbers of atoms.

Last year Monroe set a distance record of one meter for teleporting an atom from one place to another. That doesn’t mean that an actual atom was physically transferred, only that one atom’s quantum state (in this case its polarization state) was effaced from the original atom and imposed onto another atom (of the same species) far away. After the transfer no one would be able to tell that the second atom wasn’t the first atom. Previously only quantum information for photons had been teleported over distances as great as a meter.

Monroe is working to create a network of atoms contained in a device that can entangle many atoms at once and eventually undertake the kind of coherent information processing that has come to be called quantum computing. According to Monroe, the record number of atoms entangled so far is 14—achieved by Rainer Blatt of the University of Innsbruck, Austria. Monroe believes that networks as large as 50 entangled atoms will be achieved within the next few years. “A more practical question,” he said, “is establishing the number of qubits prepared in an arbitrary entangled state. Right now it’s 3 or 4, depending on who you talk to.”

New results? Monroe reported on his efforts to create a quantum magnet from the bottom up; he gets up to 9 atoms to undergo a “baby phase transition” from paramagnetic to ferromagnetic. Now he’d like to try that with 20 atoms, at which point the theoretical description becomes intractable. Thus, experiment can go where theory can’t.

Multilayer graphene

Even without Andre Geim and Konstantin Novoselov having just won this year’s physics Nobel , graphene would be a hot topic. Walt de Heer of Georgia Tech provided a little-known history of the subject and then an overview of epitaxial graphene.

Graphene didn’t just pop into prominence in the last few years. The first theories of single-sheet carbon appeared in the 1940s, de Heer said. The first report of isolated graphene sheets occurred in 1962, in a German journal; the study of “graphite monolayers” grown on silicon carbide began in 1975.

De Heer’s own efforts are devoted to developing devices based on multilayer graphene. That work, he admitted, is still at the proof-of-principle stage. He predicted that graphene would not put silicon out of business as the major microchip material, but it could succeed in select niche operations, such as high-frequency transistors. He cited an IBM prototype field emission transistor that operated at 100 GHz.

LHC now

Dan Green, a Fermilab physicist who also works on the Compact Muon Solenoid (CMS) project at the Large Hadron Collider, reported colorfully on the latest news from Geneva. It was too early for new phenomena to be uncovered, but early collisions had succeeded in recapturing previously known aspects of the standard model of particle physics—such as the production of the Z boson and the top quark.

Each proton beam at LHC, Green said, can be stored for about 10 hours, time enough for the circulating protons to travel about 10 billion kilometers, equivalent to about 65 astronomical units or a roundtrip to Pluto.

The LHC’s vacuum environment is better than that on the Moon. The cryogenic system, the largest in the world, uses 100 tons of liquid helium. The CMS main magnet, the largest solenoid magnet in the world, stores about 3 gigajoules of energy, equivalent to 600 tons of TNT, Green said. The first all-silicon event tracker, comprising 60 million pixels, operates in a gigarad radiation environment.

The luminosity—related to the intensity of the beam—is now up to about 2% of the design level and getting better quickly.

In the next month LHC will switch over from colliding protons to colliding lead ions.

Phil Schewe

All the talks at IPF 2010 were recorded and are now available on video .