  In Mott materials strong electron correlation yields a spectrum of complex
electronic structures. Recent synthesis advancements open realistic
opportunities for harnessing Mott physics to design transformative devices.
However, a major bottleneck in realizing such devices remains the lack of
control over the electron correlation strength. This stems from the complexity
of the electronic structure, which often veils the basic mechanisms underlying
the correlation strength. Here, we present control of the correlation strength
by tuning the degree of orbital overlap using picometer-scale lattice
engineering. We illustrate how bandwidth control and concurrent symmetry
breaking can govern the electronic structure of a correlated $SrVO_3$ model
system. We show how tensile and compressive biaxial strain oppositely affect
the $SrVO_3$ in-plane and out-of-plane orbital occupancy, resulting in the
partial alleviation of the orbital degeneracy. We derive and explain the
spectral weight redistribution under strain and illustrate how high tensile
strain drives the system towards a Mott insulating state. Implementation of
such concepts will drive correlated electron phenomena closer towards new solid
state devices and circuits. These findings therefore pave the way for
understanding and controlling electron correlation in a broad range of
functional materials, driving this powerful resource for novel electronics
closer towards practical realization.
