Research news
 APS meeting
 Student news

Group Title: PROTON
Title: PROTON ; vol. 7 no. 4
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00086455/00014
 Material Information
Title: PROTON ; vol. 7 no. 4
Series Title: PROTON
Physical Description: Serial
Language: English
Creator: College of Liberal Arts and Sciences, University of Florida
Publisher: University of Florida
Publication Date: April 2008
 Record Information
Bibliographic ID: UF00086455
Volume ID: VID00014
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Table of Contents
    Research news
        Page 1
    APS meeting
        Page 2
    Student news
        Page 3
        Page 4
Full Text




Outstanding Referees

* The -merican F'hgsical Societg has.
named Profs Mark Meisel and Richard
Woodard as C',utstandmng Referees
This. is the first ear of this recognition
so PlMark and Richard are among %.-.4 in
the inaugural group -ccording to the
FPS The highly select ea .ard
Man U eflIei program recognizes scientists ,ho ha e
been exceptionally helpful in assessing
manusciripts for publication in the -FPS
journalis The program ill annuially'
recognize appro.. iateily 1 :.0 of the
4'2,000 currently acti e referees. but in
the inaugural year a larger group of 5'.-4
referees has been selected for the
OC'utstanding Referee designation
,iit i The full list of ''Lutstanding Referees,
pnad along ,ith details about the program
Il oooao can be found at http //publih aps Orgl


Awards Received
Pictured II to r i are Robert Haddon IIjC.
Ri ersidel P.ildred lresselhaus ..T IiTi and
Prof Art Hebard I IIF I shortly after the
a ,ard ceremony at whichh .Mi.11 ,on the
-"FS C'i er E.ickley F'rize and -rt 1 Robert
shared the James rP..c roddgy F'rize along
ith lJun "kimiitzu Inot present The
IMc.. roddy prize ,as for the dCiiso ery of
high temperature .superconduciti it in a
non-o.die systems FPI.o.o laken t
Pi. f 4;nciL eLt P zie L

Physicists: After 30 years of study, rare particle confirms prediction
High-energy physicist de noted to recreating the condition. at the beginning of the uni er.e ha e for the
first time obier ed a ne .ay to produce those basiC particles of atoms protons. and neutronsi
Confirming a decades-old prediction the physicists .ith the C.LEC' collaboration sagy they obser ed a
rare and extremely short-li ed subatomic particle th the unusual name of Charmed-strange meson
decay into a proton and anti-neutron Detection of the e ent whichh the collaboration made public
recently at http i/ar.i org/ ,as attributed to Prof John Yelton a physiicst at the I_ini ers.ity of Florida
one of many institutions that are part of the C.LEC' collaboration It the Sort of thing that for many
gears people ha e kno ,n should happen i elton said VVhat e ha e done is sho that it does and
ho often Read full article at http /ne ,s ufi edu/2i OO'./0 l10particie-2'

Collaborators' research featured in Nature Physics
C.olliaborators at the _lni eriit, of Central Florida I C. F i the Iini eriit of California
at San Diego I IC.SDC and Prof Stephen Hill's group at the I_ni ersity of Florida
('-IF I report in Naiuie Phn sics a ne dimeric molecular nanomagnet whichh re eals,
noel topological I.erry phase effects in the quantum tunneling associated ith
interacting magnetic s, stems
_'.ee 51'icle on Pjaie -

Crystal bells stay silent as physicists look for dark matter
Fermilab U.S. experiment retakes the lead in competitive race. Scientists of the Cryogenic Dark
Matter Search experiment announced that they ha e regained the lead in the worldd ,lde race to find the
particles that make up dark matter The C. MS,,S e. periment conducted a half-mile underground in a mine
in M,,innesota again sets the worldd 5 best constraints on the properties of dark matter candidates
Read full press release at http /I nal go Ipub'presspassipress releasesicdms-resulitl-200.h html

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P-352-392-052 F32920524 *esis ews -y.uf 0 h-p/wwpy .uf~d


presented by
The Society of
Physics Students
Saturday. April 5
@ Lake Wauburg

As part of UF Library
Read-a-thon 2008,
Prof Mark Meisel will
be reading
VVhats wrongg ith this
library"' n in "E.ooums Ill
The VVay Through
C communicating
Science in a Frosaic
1O IV C'a~ ,d i le nTl
on Thursday -pril 1 at
11 30-11 40 on the
Plaza of the "mericas
for full schedule iSit
http I .,', Liflib Lifl edui
readathon/schedule hti

-lan DCorsey Chair
F'am P.arlin

college of
Liberal arts a sciences
fI it' F,',,* t,,h IL'r flic C .il1.r tN all,'


pPS Physics Faculty, Students
phySICS The March meeting of the American Physical
Society (APS) was held March 10-14, in New
Orleans, Louisiana. Over 7,000 physicists, students,
educators, journalists, and researchers attended the meeting.
There were several invited and contributed talks by our
faculty, students and postdocs:

Brian Lane, graduate student,
(Prof Kevin Ingersent),
"Conductance signatures of
quantum phase transitions in
asymmetric double quantum

Saiti Datta, graduate student,
(Prof Stephen Hill) "Looking
for higher anisotropy barriers
Photo: Brian Lane giving talk in single-molecule magnets" .

Prof Art Hebard, (invited talk, McGroddy Prize),
"Superconductivity in alkali-metal doped Carbon-60".
From Prof Hebard's group: Rajiv Misra, graduate student,
"Observation of spin-wave mediated Altshuler-Aronov and
weak localization corrections to conductivity in thin films of

From Prof Yasumasa Takano's group: Yasuo Yoshida,
post doc, "Magnetic field versus temperature phase diagram
of the spin-1/2 bond-alternating-chain antiferromagnet
F5PNN"; Younghak Kim, graduate student, Specific heat
and magnetocaloric effect of the S=1/2 spin-ladder
compound (CH3)2CHNH3CuCI3"; Travis Miller,
undergraduate student, "Low-temperature calorimeter for
magnetocaloric-effect measurements in high magnetic
fields" (supported in part by the University Scholars

Prof Peter Hirschfeld, "Structure of Bi2Sr2CaCu208+x
supermodulation from ab initio calculations". From Prof
Hirschfeld's group: Siegfried Graser, post doc, "Local
quasiparticle lifetimes in a d-wave superconductor";
Greg Boyd, graduate student, "Reversal of specific heat
oscillations with planar magnetic field in 2D d-wave
superconductors: Doppler shift beyond the nodal
approximation"; Vivek Mishra, graduate student, "Sublattice
Model of Atomic Scale Pairing Inhomogeneity in a
Superconductor"; Wei Chen, graduate student, "Magnetic
Correlations on the Full Chains of Ortho-Il YBCO6.5" and
"Disorder Induced Resistivity Upturns in Metallic Cuprates".

Photo: New Orleans paddle boat


All photos contributed by Brian Lane,
(pictured right in New Orleans)

, and Postdocs attend APS Meeting

Ranjani Narayanan,
graduate student,
(Prof Stephen
Hagen), "Coupled
folding and binding
kinetics in the
isordered peptide
IA3". Ranjani also
attended the
workshop on
Opportunities in biological physics".

Prof Ho Bun Chan, "Activation barrier scaling and switching
path distribution in a micromechanical parametric oscillator".
From Prof Ho Bun Chan's group: Yiliang Bao, graduate
student, "Measurements of the Casimir interaction between a
sphere and a rectangular corrugated plate"; Konstantinos
Ninios, graduate student, "Micromechanical force detectors
for measuring magnetization at high magnetic fields and the
magnetic response of Ba3Cr208"; Corey Stambaugh,
graduate student, "Fluctuation relations in a micromechanical
oscillator driven far from thermal equilibrium"; Zsolt Marcet,
graduate student, "Controllable evanescent field coupling
between metallic bilayers of subwavelength apertures".

From Prof Mark Meisel's group: Daniel Pajerowski,
graduate student, "Angular Dependent Magnetic
Susceptibility with Photoexcitation Studies on Prussian Blue
Analog Thin Films"; Justin Cohen, undergraduate student,
"UnderQuantum Criticality and Neutron Scattering Solutions
for a Spin-1/2 Ladder Model". To attend this meeting, Justin
Cohen was the recipient of a $500 Wentworth Travel
Scholarship administered by the UF Honors Program.

Byoung Hee Moon, graduate student, (Prof Yoonseok Lee)
"Direct Sound Propagation in Superfluid 3He-A in 98%

Lex Kemper, graduate student, (Prof Hai-Ping Cheng)
"Electronic structure of graphene in the presence of
disorder" and "Influence of oxygen orbitals on impurity states
in superconducting cuprates".

UF was well represented at the "Student Lunch with the
Experts" Session, where, at tables of 8 people, interested
students enjoyed complimentary box-lunches while
participating in an informal discussion with an expert on a
topic of interest to them. Participating UF "experts" and their
topics were Alan Dorsey (Supersolids), Stephen Hill
(Molecular Magnets), and Mark Meisel (Magnetism:
Molecule-Based Systems Where Physics Meets Chemistry).

Photo: New Orleans

Page 2




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I lan Vega, physics graduate student (Prof Steven Detweiler),
received a Student Travel Grant from the Topical Group in
Gravitation of the American Physical Society. With the grant, lan
will attend the APS April Meeting in St. Louis, Missouri. The
amount of the award was $300. lan also won the Blue
Apple Award for Best Student Talk at the 4th Gulf Coast Gravity
Meeting, held at the University of Mississippi in Oxford. Again,
this comes from the Topical Group in Gravitation of the American Physical
Society. The Blue Apple is given to four students each year, one in each of the
four gravity meetings across the US (Pacific Coast, Eastern, Midwest, and Gulf
Coast). The Gulf Coast contingent includes the universities from Texas all the
way to Florida. The award included a plaque and Blue Apple trophy, and a $200
cash prize.

The most recent issue of New Scientist features a two column
discussion with physics graduate student, Emre Kahya
(Prof Richard Woodard), on "Acid test for alternative to dark
matter". The full article can be read at
supernova-race-could-settl-dark-matter-debate. html.

Adkid be atunuhf
to do* m.Ua

The Road Less Traveled
Professors Lee and Meisel organized a
camping road trip to the MPS meeting in
New Orleans. Leaving on Saturday
morning, Lee's van carrying six and Meisel's
compact SUV carrying four, plus massive
quantities of gear, left the Physics building
loading dock and took the back roads to
Steinhatchee, where the group lunched at
the famous Roy's Restaurant on the banks
of the Steinhatchee River.

The trip continued along US 19 and 98 to St. Joseph Peninsula State Park, where

two camp sites were shared. The
everyone, and the group
included Professors Biswas,
Lee, Meisel; graduate students
Pradeep Bhupathi, Evan
Donoghue, Miguel Gonzalez,
Byoung Hee Moon, Dan
Pajerowski; and undergraduates
Justin Cohen and Jaymin
Jhaveri. After breaking camp on
Sunday morning, the rest of the
trip to New Orleans seemed
almost endless.

On a recent trip to Titusville, Deepak Kar,
physics student, snaps a picture of the
launch of the space shuttle Endeavor.

blustery and cool weather was enioyed by

Bill Malphurs receives the 2007 Superior
Accomplishment Award. Bill was unable to
receive the award at the February awards
ceremony due to illness. Welcome back
and congratulations, Bill!
Photo I to r, Prof Andrew Rinzler (accepted the
award for Bill at the ceremony), Prof Stephen
Hill (award nominator) and Bill Malphurs
(award recipient).

Page 3


Collaborators' at UCF, UF and UCSD report in Nature Physics a new
dimeric molecular nanomagnet which reveals novel topological
(Berry phase) effects in the quantum tunneling of interacting
magnetic systems
(contributed by Prof Stephen Hill)

Tunable electron spins in solid media are among the most promising candidates for qubits in
quantum computing. The synthetic flexibility of molecular nanomagnets allows one to
systematically produce samples with desirable properties such as those with entangled spin
states for implementation in quantum logic gates. A new molecular nanowheel, composed of
two coupled halves with the same spin value, represents an advance in this direction. A
magnetic field modulates the coupling between states of different spin length leading to the
observation of quantum interference-an effect that can be used to tune the entanglement of a
prototypical molecular quantum device.

Berry phase and magnetic quantum tunneling
In nanoscale magnets, such us single-molecule magnets (SMMs),
the magnetic moment (spin) can switch between opposite projections
without following a classical precession path in real space via a
quantum mechanical tunneling process. From this perspective, the
spin can also acquire a topological phase (Berry's phase) during its
quantum mechanical switching. The novelty is that, under certain
conditions and due to the quantum mechanical nature of the system,
different quantum tunneling trajectories can combine and give rise to
interference effects that may lead to a vanishing of the quantum
tunneling in the destructive case. This was predicted in 1992
separately by theorists Daniel Loss and J. von Delft and first
observed experimentally in the Fe8 SMM by Wernsdorfer and
Sessoli in 1999.

The effect of topology on the dynamics of two interacting spins is of
great interest in different disciplines. Sjoqvist was the first to study this
phenomenon in 2000 assuming two entangled spins processing
around a fixed magnetic field. It was shown that the topological phase
acquired by the entangled system could not be trivially reduced to the
sum of the Berry phases acquired by each individual spin.

Interestingly, one can trace an equivalence between two interacting A quantum dance involving the two molecular wheel
magnetic moments switching directions via quantum mechanical halves.
tunneling and the situation described by Sjqvist. Along these lines, the
UCF/UF/UCSD collaboration have provided the first experimental observation of quantum interference effects associated
with the quantum mechanical tunneling of two exchange-coupled spins associated with a SMM. This behavior is a
consequence of the unique characteristics of a molecular Mn12 wheel which behaves as a (weak) ferromagnetically
exchange-coupled molecular dimer. The molecule is composed of 12 manganese ions arranged in an annular structure
(wheel) giving rise to a ground spin state S=7 that points along the direction of the wheel axis. The total spin results from
ferromagnetic coupling between the two spin S=7/2 halves of the wheel.

The observations reveal how the interaction between the two wheel halves causes their tunneling trajectories to interfere
and, under certain conditions, the tunneling probability vanishes. This work, which is published in Nature Physics, is timely in
that a number of theoretical groups have recently discussed the possibility of utilizing the spin states of molecular magnets to
realize a quantum logic device (e.g. Leuenberger and Loss, Nature 2000). In particular, quantum interference could be
employed to turn on and off the entanglement between two qubits in a future molecular quantum device.

To read full article please visit: http://physics.ucf.edu/-delbarco/html/topology_effects.html

C. M. Ramsey, E. del Barco, S. Hill, S. J. Shah, C. Beedle and D. N. Hendrickson,
"Quantum Interference of Tunnel Trajectories between States of Different Spin Length in a Dimeric Molecular
Nanomagnet http://www.nature.com/nphys/index.html Nature Physics Advance online publication (2 March 2008):
DOI: 10.1038/nphys886.

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