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CATEGORIES:CQIF Seminar
SUMMARY:Port-based teleportation stretching of adaptive pr
otocols and conditional channel simulation - Ricca
rdo Laurenza
DTSTART;TZID=Europe/London:20181129T141500
DTEND;TZID=Europe/London:20181129T151500
UID:TALK113170AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/113170
DESCRIPTION:When we combine quantum channel simulation with qu
antum teleportation\, we obtain remarkable results
regarding the natural limitations that quantum me
chanics imposes on the optimal performance of any
quantum task performed over quantum channels. Usua
lly these ultimate limits are very difficult to ad
dress since the strategies employed to assess them
are very general and involve adaptive\, i.e. feed
back-assisted\, quantum operations\, where feedbac
k from the output is used to update the input. In
this scenario\, we first show that port-based tele
portation for channel simulation can be exploited
to devise a reduction procedure (dubbed stretching
)\, by means of which the output of an adaptive pr
otocol over arbitrary quantum channels is decompos
ed in terms of the tensor product of multicopies o
f the channelâ€™s Choi state. When we specify this t
echnique for quantum channel discrimination\, we a
re able to derive a universal computable lower bou
nd on the probability of the error affecting the d
iscrimination between two arbitrary finite-dimensi
onal quantum channels. We then show that our metho
dology can be applied also to quantum metrology\,
where we characterize the Heisenberg scaling as a
direct consequence of port-based teleportation. In
the second part of this talk we present a differe
nt design of quantum channel simulation that relie
s on a suitable control system and allows to simul
ate average quantum channels which are expressed i
n terms of ensemble of channels\, even when these
channel-components cannot be simulated through tel
eportation. We then derive relative-entropy-of-ent
anglement upper bounds for private communication o
ver various channels as the amplitude damping chan
nel\, non-Gaussian mixtures of bosonic lossy chann
els and the dephrasure channel.
LOCATION:MR4\, Centre for Mathematical Sciences\, Wilberfor
ce Road\, Cambridge
CONTACT:Johannes Bausch
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