  Entanglement is necessary but not sufficient to demonstrate nonlocality as
there exist local entangled states which do not violate any Bell inequality. In
recent years, the activation of nonlocality (known as hidden nonlocality) by
using local filtering operations has gained considerable interest. In the
original proposal of Popescu [Phys. Rev. Lett. 74, 2619 (1995)] the hidden
nonlocality was demonstrated for the Werner class of states in $d \geq 5$. In
this paper, we demonstrate the hidden nonlocality for a class of mixed
entangled states (convex mixture of a pure state and color noise) in an
arbitrary $d$-dimensional system using suitable local filtering operations. For
our demonstration, we consider the quantum violation of
Collins-Linden-Gisin-Masser-Popescu (CGLMP) inequality which has hitherto not
been considered for this purpose. We show that when the pure state in the
aforementioned mixed entangled state is a maximally entangled state, the range
of the mixing parameter for revealing hidden nonlocality increases with
increasing the dimension of the system. Importantly, we find that for $d \geq
8$, hidden non-locality can be revealed for the whole range of mixing
parameter. Further, by considering another pure state, the maximally
CGLMP-violating state, we demonstrate the activation of nonlocality by using
the same local filtering operation.

Quantum Physics