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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20170816T125347Z
DTSTART:20170817T190000Z
DTEND:20170817T200000Z
UID:event1776@bu.edu
URL:http://physics.bu.edu/events/show/1776
SUMMARY:Continuum limits of Quantum Walks
DESCRIPTION:Featuring Michael Manighalam\n\nPart of the Preliminary Oral Ex
am.\n\nExamining Committee: Mark Kon\, Alex Sushkov\, Chris Laumann\, Claud
io Rebbi\n\n\nThe quantum analog of a random walk is known as the quantum w
alk. Just as random walks have been used in computer science\, quantum walk
s have been used in many areas of quantum computing. Quantum walks have bee
n shown to match the Grover’s search algorithm speedup over classical ora
cle search algorithms\, to provide exponential speedup compared to any clas
sical algorithms in various graph traversal problems\, and more generally t
o be universal quantum computational primitives. \n\nTwo-state quantum walk
s exist as canonical discretizations of the Dirac equation\, as demonstrate
d originally by Feynman; these walks can be shown rigorously to recapture t
he Dirac equation in their continuum limit. Since their original use\, much
work has been done investigating the properties of continuum limits of qua
ntum walks. The goal of my PhD research is to address the question of wheth
er (or not) quantum scattering can be used as a universal quantum computer\
, and I plan primarily to approach this problem by connecting theorems abou
t quantum walks and their universality to scattering theory via continuum l
imits. \n\nIn this talk I will present results I have obtained about contin
uum limits of some quantum walks on the integers which are interesting in t
heir own right\, and may also give an entrée into the larger question of c
ontinuum limits of walks on graphs. In particular I will give an overview
of quantum walks and their relationships to the Dirac and Schrodinger equat
ions\, motivation for computational universality of scattering theory\, and
discuss my various results on continuum limits of quantum walks.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20170911T162601Z
DTSTART:20170912T190000Z
DTEND:20170912T200000Z
UID:event1826@bu.edu
URL:http://physics.bu.edu/events/show/1826
SUMMARY:Constructing Ultra-Slow Glasses in Lattice Models for Reversible Co
mputing
DESCRIPTION:Featuring Lei Zhang\n\nPart of the Preliminary Oral Exam.\n\nEx
amining Committee: Andrei Ruckenstein\, Claudio Chamon\, Michael El-Batano
uny\, Richard Brower\n\nAbstract:\n\nWe construct a two-dimensional lattice
model that lacks any finite temperature phase transition and yet displays
relaxation times that grow as a double exponential of the inverse temperatu
re. The model has bulk translational invariance\, only broken by the presen
ce of the boundaries. The lattice model is associated to a reversible circu
it that can multiply or factorize integers\, depending on the boundary cond
itions. When the lattice model reaches its ground state\, all computations
are performed without error. The ultra-slow (double exponential in inverse
temperature) glassy dynamics is associated with the difficulty of the syste
m to heal computational errors that cost little energy but flip a volumetri
c number of bits in the system.\n\n![Lei](/resources/event-image/1826/af5ae
ef_small)
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20170901T145009Z
DTSTART:20170913T180000Z
DTEND:20170913T190000Z
UID:event1817@bu.edu
URL:http://physics.bu.edu/events/show/1817
SUMMARY:Numerical Signatures of Conformal Field Theory
DESCRIPTION:Featuring Pranay Patil\n\nPart of the Preliminary Oral Exam.\n\
nAbstract: Conformal Field theory has important consequences for quantum ph
ase transitions and dynamical response of lattice models and as it is not a
lways possible to analytically determine if a lattice model has a low energ
y conformal description\, we need to find numerical signatures which can re
liably help us identify a CFT. Here we look at how entanglement entropy and
correlation functions fare as candidates for CFT signatures using some exa
mples of established CFTs such as the 2d classical Ising model and 1d Heise
nberg chain. We also explore some interesting properties of the 1d Heisenbe
rg chain using these numerics.\n\nDissertation committee: Anders Sandvik\,
Claudio Chamon\, Emanuel Katz\, Alex Sushkov \n\n![Pranay](/resources/event
-image/1817/00307ec_small)
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20170907T183607Z
DTSTART:20170918T173000Z
DTEND:20170918T183000Z
UID:event1799@bu.edu
URL:http://physics.bu.edu/events/show/1799
SUMMARY:Market Bubbles: Collective Behavior in the Financial Market
DESCRIPTION:Featuring Chon Kit Pun\n\nPart of the Preliminary Oral Exam.\n\
nExamining Committee: William Klein\, Harvey Gould\, Kirill Korolev\, Chris
topher Grant\, Alex Sushkov\n\nAbstract:\n\n\nFrom the stock bubbles in the
1920s\, which eventually led to the Great Depression in the 1930s\, to the
recent boom and bust of the real estate bubbles in 2007-2009\, market bubb
les have been the main source of instability in the financial market. While
speculators and momentum traders are blamed to have driven the price away
from the reasonable level during the formation of a bubble\, value investor
s like the fund managers may sometimes fail to correct the price and instea
d join 'riding the bubble'\, which help growing the bubble further.\n\nIn t
his talk I will present an agent-based model of how the collective behavior
of traders give rise to a bubble. In this model traders learn which assets
to invest by using the Experience Weighted Attraction (EWA) learning algor
ithm\, which has its root in both behavioral psychology and game theory and
has seen applications in social science and economics. I will show that wh
en traders tend to invest in the `winning' asset\, memory and liquidity pla
y an important role in the formation\nof bubbles. The discussion of the res
ult will be emphasized on the implication to the real market\, and on the c
omparison with statistical physics.
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20171101T142607Z
DTSTART:20171103T180000Z
DTEND:20171103T190000Z
UID:event1854@bu.edu
URL:http://physics.bu.edu/events/show/1854
SUMMARY: Learning and Optimizing Quantum Control Landscapes
DESCRIPTION:Featuring Alexandre Day\n\nPart of the Preliminary Oral Exam.\n
\nAbstract:\nThe ability to prepare quantum states rapidly and with high fi
delity is a crucial step towards\nfully scalable quantum computers. In this
talk I will discuss the existence of phase transitions in the quantum stat
e preparation problem as a function of the constraint parameters (field str
engths and ramp time). We study the different phases and discuss their sign
ificance in terms of complexity and robustness for the quantum state prepar
ation problem.
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20171116T215342Z
DTSTART:20171120T184500Z
DTEND:20171120T194500Z
UID:event1855@bu.edu
URL:http://physics.bu.edu/events/show/1855
SUMMARY:Kibble-Zurek Dynamics of a Driven Dissipative System: Universality
Beyond the Markovian Regime
DESCRIPTION:Featuring Renzo Tamiro Villazon Scholer\n\nPart of the Prelimin
ary Oral Exam.\n\nExamining Committee: Anushya Chandran\, Anatoli Polkovni
kov\, Wanzheng Hu\, and Liam Fitzpatrick\n\nAbstract:\n\n\nDriven-disipativ
e phase transitions in open systems provide a rich avenue for the study of
many-body non-equilibrium phenomena. These systems exhibit unique propertie
s depending on the detailed nature of their system-bath interactions\, whic
h may nontrivially alter their critical dynamics\, and which are amenable t
o study by slow ramps across the critical point. In this talk\, I will disc
uss Kibble-Zurek dynamics in a paradigmatic two-mode driven-dissipative sys
tem of a pair of non-degenerate parametrically coupled\, optomechanical osc
illators. I will detail the key theoretical aspects of the model and it's p
redictions on universality\, which have been confirmed in experiments by ou
r collaborators in the Vengalattore group at Cornell University.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20171215T101213Z
LAST-MODIFIED:20171211T160928Z
DTSTART:20171220T143000Z
DTEND:20171220T153000Z
UID:event1870@bu.edu
URL:http://physics.bu.edu/events/show/1870
SUMMARY:Constraints on Flavored 2d CFT Partition Functions
DESCRIPTION:Featuring Yuan Xin\n\nPart of the Preliminary Oral Exam.\n\nExa
mining Committee: Liam Fitzpatrick\, Ami Katz\, Robert Carey\, Christopher
Laumann\n\nAbstract:\n\nConformal Field Theory (CFT) relates to many open
questions in high-energy physics and condensed matter theory\, and brings u
s important insights into Quantum Gravity via the AdS/CFT correspondence. T
he conformal bootstrap is a powerful approach to CFT that allows one to stu
dy such theories beyond the weakly coupled regime\, using only basic univer
sal principles. In this project\, we perform a bootstrap analysis on all 2
dimensional CFTs with a conserved charge\, using the transformation law for
the modular transformation of the CFT’s partition function in the presen
ce of a chemical potential\, i.e. flavored partition function. First\, we u
se this law to put constraints on the CFT’s "mass-to-charge" ratio\, as w
ell as the weight of charged states in the theory. Then\, we apply the extr
emal functional method to extract the partition functions of the CFTs that
saturate the bounds. In several cases we find the prediction of the occupat
ion numbers are precisely integers\, which is necessary for a physical theo
ry. Our bounds provide a solid proof of the 3-dimensional Quantum Gravity c
ase of the Weak Gravity Conjecture\, and we find some previously inaccessib
le partition functions.
LOCATION:PRB 595\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
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