Interfaces in heterostructures often exhibit emergent physical properties that are absent in the constituent layers. These heterostructures, together with their compatibility with nanofabrication, are promising for constructing functional quantum devices. I will illustrate the capability of such heterostructure engineering by taking two examples. I will first explain our discovery of a versatile method for synthesizing ferroelectric materials from non-ferroelectric two-dimensional (2D) materials: by physically stacking two monolayer boron nitrides at controlled angles, novel types of ferroelectricity emerge at the interface. I will demonstrate its functionality as one of the world’s thinnest ferroelectric non-volatile memories at room temperature. As another example, I will demonstrate the versatile spintronic functionalities of topological insulator heterostructures synthesized by a thin film growth method. I will conclude by discussing how we can overcome the limits of existing heterostructure engineering for the future design of quantum materials and functionalities.