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VERSION:2.0
PRODID:Icfo
X-PUBLISHED-TTL:P1W
BEGIN:VEVENT
UID:6abfa9e1045ce
DTSTART:20261020T100000Z
SEQUENCE:0
TRANSP:OPAQUE
DTEND:20261020T110000Z
LOCATION:Seminar Room
SUMMARY:ICFO | MATHEUS CAPELA
CLASS:PUBLIC
DESCRIPTION:The causal structure of physical processes is usually assumed t
 o be fixed: events occur in a definite order\, even when the underlying qu
 antum systems exhibit nonclassical correlations. Quantum theory\, however\
 , allows for more general processes in which the causal order itself can b
 e indefinite\, as exemplified by the quantum switch. This raises a fundame
 ntal question: can the causal structure of a process be characterized pure
 ly in terms of the information it can transmit?In this talk\, I will discu
 ss an information-theoretic approach to this question based on information
  inequalities. We derive a class of inequalities that must hold for any pr
 ocess compatible with a fixed causal order\, including both definite causa
 l orders and classical mixtures thereof. Their violation therefore provide
 s a sufficient condition for certifying genuinely non-fixed causal order. 
 Remarkably\, the framework is not restricted to the von Neumann entropy\, 
 but extends to a broad class of information measures\, including R&eacute\
 ;nyi entropies.I will also discuss how these inequalities can be combined 
 with strong subadditivity to obtain witnesses that require only marginal i
 nformation\, and show how the resulting criteria detect the non-fixed caus
 al structure of the quantum switch. These results highlight a direct conne
 ction between information-theoretic constraints and the causal structure o
 f quantum processes.
DTSTAMP:20261002T125601Z
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