BEGIN:VCALENDAR
PRODID:-//eluceo/ical//2.0/EN
VERSION:2.0
CALSCALE:GREGORIAN
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1379
DTSTAMP:20240103T081941Z
SUMMARY:One Shot Non-Catalytic Distributed Purity Distillation
DESCRIPTION:Speaker: Dr. Sayantan Chakraborty (Centre for Quantum Technolog
ies\, National University of Singapore)\n\nAbstract: \nPure states are an
important resource in many quantum information processing protocols. Howev
er\, even making a fixed pure state\, say $\\vert 0 \\rangle$\, in the lab
oratory requires a considerable amount of effort. Often one ends up with a
mixed state $\\rho$ whose classical description is nevertheless known. He
nce it is important to develop protocols that extract a fixed pure state f
rom a known mixed state. In this work\, we study the problem of extracting
a fixed pure state $\\vert 0 \\rangle^{A'} \\vert{0}\\rangle^{B'}$ from a
known pure state $\\rho^{AB}$ distributed between two parties $A$ and $B$
. Here\, $A'$\, $B'$ are subspaces of $A$\, $B$ and the total amount of pu
rity extracted is $\\log |A'| + \\log |B'|$. The parties can borrow local
pure ancilla\, apply local unitary operations and send a message from $A$
to $B$ through a dephasing channel. If local pure ancilla is borrowed\, it
must be subtracted in order to properly account for the purity extracte
d. We obtain the most efficient achievable bounds on one shot distributed
purity extraction\, in terms of the rate of local ancilla borrowed by the
protocol\, while distilling pure qubits at the best known rate. Our protoc
ols borrow little to no local pure ancilla. Our bounds improve upon the ex
isting bounds for this problem in both one shot as well as asymptotic iid
settings. In particular they subsume all the asymptotic iid results of Dev
etak and Krovi-Devetak. In addition\, we derive upper bounds for the rate
of distillation in the one shot setting\, which nearly match our achievabl
e bounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1379
DTSTART;TZID=Asia/Kolkata:20240103T160000
DTEND;TZID=Asia/Kolkata:20240103T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
END:VCALENDAR