  The generally accepted view in quantum theory is that information about which
way the quantum system traveled and interference visibility are complementary.
In all which-way experiments, however, an intervention takes place in the
interference process in order to determine which way the quantum system took.
This intervention can imply the tagging of a which-way marker to a quantum
system or, for instance, blocking off one of the paths in a Mach-Zehnder
interferometer so that one indirectly knows that the quantum system took the
other (open) path. It is, however, this intervention that destroys the
interference. In this paper a novel two-slit which-way interference experiment
will be discussed and proposed for implementation that provides maximum
which-way information without intervening in the interference process so that
simultaneously maximum interference visibility remains preserved. This, in
fact, implies an uncoupling of which-way information from interference and
consequently also entails violating the duality relation P^2+V^2<1. Basically,
the purpose of the proposed experiment and of this paper is to scrutinize this
duality relation. The experiment makes use of a super-focused laser beam that
is launched into only one of the two slits of the two-slit interference
experiment.
