Shader model 6.3 adds support for DirectX12 Raytracing (DXR). This includes new intrinsics for casting rays into acceleration data structures, and processing the results. See the DX12 raytracing documentation. It also includes official HLSL compiled DXIL libraries and linking of shaders from these libraries, which has applications beyond raytracing.

An overview blog post on DirectX raytracing ishere

Developer documentation on DirectX raytracing ishere

The DirectX12 Raytracing samples on GitHub are locatedhere