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DTSTART:20240310T070000
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DTSTART:20231105T060000
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DTSTART;TZID=America/Toronto:20240422T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240422T153000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/deep-reinfo
rcement-learning-perform-error-rate-aware-qubit
SUMMARY:Deep Reinforcement Learning to Perform Error Rate Aware Qubit Routi
ng\nand Circuit Optimization
CLASS:PUBLIC
DESCRIPTION:Summary \n\nIQC SEMINAR - ALEXANDER GEORGE-KENNEDY\, GEORGIA TE
CH\n\nQuantum-Nano Centre\, 200 University Ave West\, Room QNC 1201 Waterl
oo\,\nON CA N2L 3G1\n\nProtecting quantum information against noise is a w
idespread goal in\nquantum computation. In addition to implementing quantu
m error\ncorrecting codes\, classical pre-processing steps of circuit\nopt
imization and qubit routing can greatly increase the fidelity of\nthe resu
lt of a quantum computation. Prior work has shown that neural\nnetworks an
d/or reinforcement learning can be used to discover quantum\nerror correct
ing codes\, perform qubit routing optimized for circuit\ndepth\, and find
optimal points to insert dynamical decoupling pulse\nsequences in a quantu
m circuit. We extend prior work by creating a\ndeep reinforcement learning
directed transpiler. We treat the problem\nof qubit routing and circuit o
ptimization together\, and can regard it\nas a single-player “game\,”
where the objective is minimizing the\noutput circuit's estimated noise\,
subject to the connectivity\nconstraints of the architecture. The “moves
” in this game\navailable to the transpiler are selecting the qubit layo
ut\,\nintroducing SWAP gates subject to architecture constraints\, and\nre
writing the circuit according to equivalency rules (such as\nintroducing d
ynamical decoupling sequences\, or simply optimizing away\nrepeated self-a
djoint gates). We train a transpiler for a specific\nquantum device\, in o
ur experiments\, each of the available 5-qubit IBM\ndevices\, crucially in
cluding the reported error rates per gate per\nqubit per device as part of
the transpiler training data. Running the\ntranspilers on a series of ran
dom circuits across different devices\,\nwe compare the transpiler output
circuits with IBM's transpiler\noutputs. We find an average improvement of
17% reduction in output\nerror rate compared to the IBM transpiler. This
is an improvement on\nprior work that also uses a neural network as a nois
e-indicating\nobjective function\, but with no explicit loading of device
error\nrates\, a different vectorization of circuits\, and a greedy circui
t\nrewrite policy. Our work is ongoing\, as we intend to extend the\ntrans
piler's capability in the vein of prior work to construct error\ncorrectin
g codes during optimization.\n
DTSTAMP:20240420T062601Z
END:VEVENT
BEGIN:VEVENT
UID:66235ff97066a
DTSTART;TZID=America/Toronto:20240416T150000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240416T160000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/recent-prog
ress-hamiltonian-learning
SUMMARY:Recent progress in Hamiltonian learning
CLASS:PUBLIC
DESCRIPTION:Summary \n\nCS/MATH SEMINAR - YU TONG\, CALTECH\n\nQuantum-Nano
Centre\, 200 University Ave West\, Room QNC 1201 + ZOOM\nWaterloo\, ON CA
N2L 3G1\n\nIn the last few years a number of works have proposed and impr
oved\nprovably efficient algorithms for learning the Hamiltonian from\nrea
l-time dynamics. In this talk\, I will first provide an overview of\nthese
developments\, and then discuss how the Heisenberg limit\, the\nfundament
al precision limit imposed by quantum mechanics\, can be\nreached for this
task. I will demonstrate how the Heisenberg limit\nrequires techniques th
at are fundamentally different from previous\nones\, and the important rol
es played by quantum control and\nthermalization. I will also discuss open
problems that are crucial to\nmaking these algorithms implementable on cu
rrent devices.\n
DTSTAMP:20240420T062601Z
END:VEVENT
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DTSTART;TZID=America/Toronto:20240417T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240417T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-benjamin-maclellan
SUMMARY:IQC Student Seminar Featuring Benjamin MacLellan
CLASS:PUBLIC
DESCRIPTION:Summary \n\nVARIATIONAL METHODS FOR QUANTUM SENSING\n\nQuantum-
Nano Centre\, 200 University Ave West\, Room QNC 1201 Waterloo\,\nON CA N2
L 3G1\n\nThe precise estimation of unknown physical quantities is foundati
onal\nacross science and technology. Excitingly\, by harnessing\ncarefully
-prepared quantum correlations\, we can design and implement\nsensing prot
ocols that surpass the intrinsic precision limits imposed\non classical ap
proaches. Applications of quantum sensing are myriad\,\nincluding gravitat
ional wave detection\, imaging and microscopy\,\ngeoscience\, and atomic c
locks\, among others.\n\nHowever\, current and near-term quantum devices h
ave limitations that\nmake it challenging to capture this quantum advantag
e for sensing\ntechnologies\, including noise processes\, hardware constra
ints\, and\nfinite sampling rates. Further\, these non-idealities can prop
agate and\naccumulate through a sensing protocol\, degrading the overall\n
performance and requiring one to study protocols in their entirety.\n\nIn
recent work [1]\, we develop an end-to-end variational framework for\nquan
tum sensing protocols. Using parameterized quantum circuits and\nneural ne
tworks as adaptive ansätze of the sensing dynamics and\nclassical estimat
ion\, respectively\, we study and design variational\nsensing protocols un
der realistic and hardware-relevant constraints.\nThis seminar will review
the fundamentals of quantum metrology\, cover\ncommon sensing application
s and protocols\, introduce and benchmark our\nend-to-end variational appr
oach\, and conclude with perspectives on\nfuture research.\n\n[1] https:/
/arxiv.org/abs/2403.02394\n
DTSTAMP:20240420T062601Z
END:VEVENT
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DTSTART;TZID=America/Toronto:20240409T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240409T123000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/new-techniq
ues-fast-and-high-fidelity-trapped-ion-0
SUMMARY:New Techniques for Fast and High-Fidelity Trapped Ion Interconnects
CLASS:PUBLIC
DESCRIPTION:Summary \n\nIQC SEMINAR - JAMESON O'REILLY\, DUKE UNIVERSITY\n\
nQuantum-Nano Centre\, 200 University Ave West\, Room QNC 0101 \nWaterloo
\, ON CA N2L 3G1\n\nTrapped atomic ions are a leading candidate platform f
or quantum\nsimulation and computing but system sizes are limited by motio
nal mode\ncrowding and transport overhead. Multiple reasonably-sized\,\nwe
ll-controlled modules can be connected into one universal system\nusing ph
otonic interconnects\, in which photons entangled with ions in\neach trap
are collected into and detected in a Bell-state analyzer.\nThe speed of th
ese interconnects has heretofore been limited by the\nuse of 0.6 NA object
ives and the need to periodically pause\nentanglement attempts for recooli
ng. In this work\, we use a system\nwith two in-_vacuo_ 0.8 NA lenses on
either side of an ion trap to\ncollect 493 nm photons from barium ions and
demonstrate the most\nefficient free-space ion trap photonic interconnect
to date. In\naddition\, we introduce an ytterbium ion as a sympathetic co
olant\nduring the entangling attempts cycle to remove the need for recooli
ng\,\nenabling a record photon-mediated entanglement rate between two\ntra
pped ions. The major remaining error source is imperfections in the\nphoto
n polarization encoding\, so we also develop a new protocol for\nremotely
entangling two ions using time-bin encoded photons and\npresent preliminar
y results of an experimental implementation.\nFinally\, we prepare the fir
st remote entangled state involving two\nbarium ions in separate vacuum ch
ambers.\n
DTSTAMP:20240420T062601Z
END:VEVENT
BEGIN:VEVENT
UID:66235ff972f9a
DTSTART;TZID=America/Toronto:20240410T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240410T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-matthew-duschenes
SUMMARY:IQC Student Seminar Featuring Matthew Duschenes
CLASS:PUBLIC
DESCRIPTION:Summary \n\nOVERPARAMETERIZATION AND EXPRESSIVITY OF REALISTIC
QUANTUM SYSTEMS\n\nQuantum-Nano Centre\, 200 University Ave West\, Room QN
C 1201 Waterloo\,\nON CA N2L 3G1\n\nQuantum computing devices require exce
ptional control of their\nexperimental parameters to prepare quantum state
s and simulate other\nquantum systems\, in particular while subject to noi
se. Of interest\nhere are notions of trainability\, how difficult is it to
classically\noptimize parameterized\, realistic quantum systems to repres
ent target\nstates or operators of interest\, and expressivity\, how much
of a\ndesired set of these targets is our parameterized ansatze even capab
le\nof representing? We observe that overparameterization phenomena\, wher
e\nsystems are adequately parameterized\, are resilient in noisy settings\
nat short times and optimization can converge exponentially with\ncircuit
depth. However fidelities decay to zero past a critical depth\ndue to accu
mulation of either quantum or classical noise. To help\nexplain these nois
e-induced phenomena\, we introduce the notion of\nexpressivity of non-unit
ary\, trace preserving operations\, and\nhighlight differences in average
behaviours of unitary versus\nnon-unitary ensembles. We rigorously prove t
hat highly-expressive\nnoisy quantum circuits will suffer from barren plat
eaus\, thus\ngeneralizing reasons behind noise-induced phenomena. Our resu
lts\ndemonstrate that appropriately parameterized ansatze can mitigate\nen
tropic effects from their environment\, and care must be taken when\nselec
ting ansatze of channels.\n
DTSTAMP:20240420T062601Z
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BEGIN:VEVENT
UID:66235ff973c60
DTSTART;TZID=America/Toronto:20240328T130000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240328T140000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/smooth-min-
entropy-lower-bounds-approximation-chains
SUMMARY:Smooth min-entropy lower bounds for approximation chains
CLASS:PUBLIC
DESCRIPTION:Summary \n\nIQC SEMINAR - ASHUTOSH MARWAH\, UNIVERSITY OF MONTR
EAL\n\nQuantum-Nano Centre\, 200 University Ave West\, Room QNC 1201\nWate
rloo\, ON CA N2L 3G1\n\nFor a state $\\rho_{A_1^n B}$\, we call a sequence
of states\n$(\\sigma_{A_1^k B}^{(k)})_{k=1}^n$ an approximation chain if
for every\n$1 \\leq k \\leq n$\, $\\rho_{A_1^k B} \\approx_\\epsilon \\sig
ma_{A_1^k\nB}^{(k)}$. In general\, it is not possible to lower bound the s
mooth\nmin-entropy of such a $\\rho_{A_1^n B}$\, in terms of the entropies
of\n$\\sigma_{A_1^k B}^{(k)}$ without incurring very large penalty factor
s.\nIn this paper\, we study such approximation chains under additional\na
ssumptions. We begin by proving a simple entropic triangle\ninequality\, w
hich allows us to bound the smooth min-entropy of a state\nin terms of the
R\\'enyi entropy of an arbitrary auxiliary state while\ntaking into accou
nt the smooth max-relative entropy between the two.\nUsing this triangle i
nequality\, we create lower bounds for the smooth\nmin-entropy of a state
in terms of the entropies of its approximation\nchain in various scenarios
. In particular\, utilising this approach\, we\nprove approximate versions
of the asymptotic equipartition property\nand entropy accumulation. In a
companion paper\, we show that the\ntechniques developed in this paper can
be used to prove the security\nof quantum key distribution in the presenc
e of source correlations.\n
DTSTAMP:20240420T062601Z
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BEGIN:VEVENT
UID:66235ff974591
DTSTART;TZID=America/Toronto:20240320T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240320T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-sarah-li-1
SUMMARY:IQC Student Seminar Featuring Sarah Li
CLASS:PUBLIC
DESCRIPTION:Summary \n\nIMPROVING THE FIDELITY OF CNOT CIRCUITS ON NISQ HAR
DWARE\n\nQuantum-Nano Centre\, 200 University Ave West\, Room QNC 1201 Wat
erloo\,\nON CA N2L 3G1\n\nWe introduce an improved CNOT synthesis algorith
m that considers\nnearest-neighbour interactions and CNOT gate error rates
in noisy\nintermediate-scale quantum (NISQ) hardware. Our contribution is
\ntwofold. First\, we define a \\Cost function by approximating the\navera
ge gate fidelity Favg. According to the simulation results\, \\Cost\nfits
the error probability of a noisy CNOT circuit\, Prob = 1 - Favg\,\nmuch ti
ghter than the commonly used cost functions. On IBM's fake\nNairobi backen
d\, it fits Prob with an error at most 10^(-3). On other\nbackends\, it fi
ts Prob with an error at most 10^(-1). \\Cost accounts\nfor the machine ca
libration data\, and thus accurately quantifies the\ndynamic error charact
eristics of a NISQ-executable CNOT circuit.\nMoreover\, it circumvents the
computation complexity of calculating\nFavg and shows remarkable scalabil
ity. \n\nSecond\, we propose an architecture-aware CNOT synthesis algorit
hm\,\nNAPermRowCol\, by adapting the leading Steiner-tree-based synthesis\
nalgorithms. A weighted edge is used to encode a CNOT gate error rate\nand
\\Cost-instructed heuristics are applied to each reduction step.\nCompare
d to IBM's Qiskit compiler\, it reduces \\Cost by a factor of 2\non averag
e (and up to a factor of 8.8). It lowers the synthesized CNOT\ncount by a
factor of 13 on average (up to a factor of 162). Compared\nwith algorithms
that are noise-agnostic\, it is effective and scalable\nto improve the fi
delity of CNOT circuits. Depending on the benchmark\ncircuit and the IBM b
ackend selected\, it lowers the synthesized CNOT\ncount up to 56.95% compa
red to ROWCOL and up to 21.62% compared to\nPermRowCol. It reduces the syn
thesis \\Cost up to 25.71% compared to\nROWCOL and up to 9.12% compared to
PermRowCol. NAPermRowCol improves\nthe fidelity and execution time of a s
ynthesized CNOT circuit across\nvaried NISQ hardware. It does not use anci
llary qubits and is not\nrestricted to certain initial qubit maps. It coul
d be generalized to\nroute a more complicated quantum circuit\, and eventu
ally boost the\noverall efficiency and accuracy of quantum computing on NI
SQ\ndevices. \n\nJoint-work with: Dohun Kim\, Minyoung Kim\, and Michele
Mosca\n
DTSTAMP:20240420T062601Z
END:VEVENT
BEGIN:VEVENT
UID:66235ff974ee4
DTSTART;TZID=America/Toronto:20240221T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240221T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-kieran-mastel-0
SUMMARY:IQC Student Seminar Featuring Kieran Mastel
CLASS:PUBLIC
DESCRIPTION:Summary \n\nTHE CLIFFORD THEORY OF THE N-QUBIT CLIFFORD GROUP\n
\nQuantum-Nano Centre\, 200 University Ave West\, Room QNC 1201 Waterloo\,
\nON CA N2L 3G1\n\nThe n-qubit Pauli group and its normalizer the n-qubit
Clifford group\nhave applications in quantum error correction and device\n
characterization. Recent applications have made use of the\nrepresentation
theory of the Clifford group. We apply the tools of\n(the coincidentally
named) Clifford theory to examine the\nrepresentation theory of the Cliffo
rd group using the much simpler\nrepresentation theory of the Pauli group.
We find an unexpected\ncorrespondence between irreducible characters of t
he n-qubit Clifford\ngroup and those of the (n + 1)-qubit Clifford group.
This talk will\nrely on the explanation of Clifford theory given last week
.\n
DTSTAMP:20240420T062601Z
END:VEVENT
BEGIN:VEVENT
UID:66235ff9756b3
DTSTART;TZID=America/Toronto:20240214T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240214T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-kieran-mastel
SUMMARY:IQC Student Seminar Featuring Kieran Mastel
CLASS:PUBLIC
DESCRIPTION:Summary \n\nA QUICK INTRODUCTION TO CLIFFORD THEORY\n\nQuantum-
Nano Centre\, 200 University Ave West\, Room QNC 1201 Waterloo\,\nON CA N2
L 3G1\n\nClifford theory studies the connection between representations of
a\ngroup and those of its normal subgroups. In recent work\, I examined\n
the Clifford theory of the Clifford group to determine parts of its\nchara
cter table for future applications. The goal of this talk is to\nintroduce
the representation theory and Clifford theory of finite\ngroups sufficien
tly to understand next week's talk when I will explain\nthe Clifford theor
y of the n-qubit Clifford group. Note that these are\ntwo distinct Cliffor
ds. I may also briefly discuss the applications of\nClifford theory in qua
ntum error correction\, time permitting.\n
DTSTAMP:20240420T062601Z
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BEGIN:VEVENT
UID:66235ff975d88
DTSTART;TZID=America/Toronto:20240131T120000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20240131T130000
URL:https://uwaterloo.ca/institute-for-quantum-computing/events/iqc-student
-seminar-featuring-amolak-ratan-kalra-0
SUMMARY:IQC Student Seminar Featuring Amolak Ratan Kalra
CLASS:PUBLIC
DESCRIPTION:Summary \n\nARITHMETIC AND SYNTHESIS OF QUANTUM CIRCUITS\n\nRes
earch Advancement Centre\, 475 Wes Graham Way\, Room RAC 2009\,\nWaterloo\
, ON\, CA N2L 6R2\n\nIn this talk I will introduce some basic aspects of q
uantum circuit\nsynthesis over various gate sets for qubits and qutrits. T
he main\nreference for this work is: https://arxiv.org/pdf/2311.08696.pdf
\n \nI will also talk about the relationship between synthesis\, SIC-P
OVMs\nand magic states. This is work done with Dinesh Valluri\, Michele\nM
osca\, Jon Yard\, Sam Winnick and Manimugdha Saikia.
DTSTAMP:20240420T062601Z
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