Quantum Information Seminar
Hemant
Katiyar
Ph.D.
Graduate
Student,
Physics
(Quantum
Information)
Abstract:
The
Leggett–Garg
(LG)
test
of
macroscopic
realism
involves
a
series
of
dichotomic
non-invasive measurements
that
are
used
to
calculate
a
function
which
has
a
fixed
upper
bound
for
a
macrorealistic system
and
a
larger
upper
bound
for
a
quantum
system.
The
quantum
upper
bound
depends
on
both the
details
of
the
measurement
and
the
dimension
of
the
system.
Here
we
present
an
LG
experiment on
a
three-level
quantum
system,
which
produces
a
larger
theoretical
quantum
upper
bound
than
that of
a
two-level
quantum
system.
The
experiment
is
carried
out
in
nuclear
magnetic
resonance
and consists
of
the
LG
test
as
well
as
a
test
of
the
ideal
assumptions
associated
with
the
experiment,
such
as measurement
non-invasiveness.
The
non-invasive
measurements
are
performed
via
the
modified ideal
negative
result
measurement
scheme
on
a
three-level
system.
Once
these
assumptions
are
tested, the
violation
becomes
small,
despite
the
fact
that
the
LG
value
itself
is
large.
Our
results
showcase
the advantages
of
using
the
modified
measurement
scheme
that
can
reach
higher
LG
values,
since
these leave
a
larger
margin
for
violating
the
inequality
in
the
face
of
experimental
imperfections.