Wednesday, January 20, 2016 11:00 am

11:00 am
EST (GMT 05:00)
QNC 4401
Candidate
Daniel Puzzuoli Applied Math, University of Waterloo
Title
Ancilla dimension for optimal channel discrimination
Abstract
In
this
seminar
we
will
discuss
the
role
of
the
ancilla
dimension
in
channel
discrimination
problems.
We
will
review
state
and
channel
discrimination
games
and
present
what
is
known
about
optimal
success
probabilities
in
these
games,
with
emphasis
on
role
of
the
dimension
of
the
ancilla
system.
It
is
well
known
that
an
ancilla
with
dimension
equal
to
the
input
dimension
of
the
channels
being
discriminated
is
always
sufficient
for
optimal
channel
discrimination.
A
natural
question
then,
is
when
the
output
dimension
is
smaller
than
the
input
dimension,
is
optimal
discrimination
always
possible
when
the
ancilla
has
dimension
equal
to
that
of
the
output
system?
We
will
show
that
the
answer
is
no
by
providing
a
family
of
counter
examples.
Interestingly,
this
family
contains
instances
with
arbitrary
finite
gap
between
the
input
and
output
dimensions,
and
also
has
the
property
that,
even
with
arbitrary
finite
gap,
an
ancilla
of
any
dimension
less
than
the
input
dimension
is
insufficient
for
optimal
discrimination.
Future
directions
and
numerical
investigations
will
also
be
discussed.