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UID:/NewsandEvents/Archives/2015/newsitem/6934/16-
 June-2015-Theoretical-Computer-Science-Seminar-Jer
 emy-Ribeiro
DTSTAMP:20150611T000000
SUMMARY:Theoretical Computer Science Seminar, Jere
 my Ribeiro
ATTENDEE;ROLE=Speaker:Jeremy Ribeiro
DTSTART;TZID=Europe/Amsterdam:20150616T150000
DTEND;TZID=Europe/Amsterdam:20150616T160000
LOCATION:CWI room L017, Science Park 123, Amsterda
 m
DESCRIPTION:We use the entanglement sampling techn
 iques developed in (Dupuis et al., 2015) to find a
  lower bound on the entanglement needed by a coali
 tion of cheaters attacking the quantum postition v
 erification protocol using the four BB84 states (Q
 PVBB84) in the scenario where the cheaters have no
  access to a quantum channel but share a (possibly
  mixed) entangled state Φ. For a protocol using n 
 qubits, a necessary condition for cheating is that
  the max-relative entropy of entanglement E_max(Φ)
  ≥ n − O(log n). This improves previously known be
 st lower bound by a factor approx. 4, and it is es
 sentially tight, since the protocol is vulnerable 
 to a teleportation-based attack using n − O(1) ebi
 ts of entanglement.  For more information, see the
  article at http://arxiv.org/abs/1504.07171 or con
 tact Christian Schaffner (c.schaffner at uva.nl).
X-ALT-DESC;FMTTYPE=text/html:\n        <p>We use t
 he entanglement sampling techniques developed in (
 Dupuis et al., 2015) to find a lower bound on the 
 entanglement needed by a coalition of cheaters att
 acking the quantum postition verification protocol
  using the four BB84 states (QPVBB84) in the scena
 rio where the cheaters have no access to a quantum
  channel but share a (possibly mixed) entangled st
 ate &Phi;. For a protocol using n qubits, a necess
 ary condition for cheating is that the max-relativ
 e entropy of entanglement E_max(&Phi;) &ge; n &min
 us; O(log n). This improves previously known best 
 lower bound by a factor approx. 4, and it is essen
 tially tight, since the protocol is vulnerable to 
 a teleportation-based attack using n &minus; O(1) 
 ebits of entanglement.</p>\n    \n        <p>For m
 ore information, see the article at <a target="_bl
 ank" href="http://arxiv.org/abs/1504.07171">http:/
 /arxiv.org/abs/1504.07171</a> or contact Christian
  Schaffner (<a class="email">c.schaffner <span cla
 ss="at">at</span> uva.nl</a>).</p>\n    
URL:/NewsandEvents/Archives/2015/newsitem/6934/16-
 June-2015-Theoretical-Computer-Science-Seminar-Jer
 emy-Ribeiro
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