What is the meaning of tensor_A?
I can assume that tensor_B is a batch of 64x64 RGB images. Your operation creates a batch of 100 channel 64x64 images (where these 64x64 pixels all have the same value) and adds those channels to each of the tensor_B images.
A more efficient operation would be to change:
tensor_A = tensor_A.view(16, 100, 1, 1)
tensor_A = tensor_A * torch.ones(16, 100, 64, 64, device=‘cuda’)

to:
tensor_A = tensor_A.view(16, 100, 1, 1).expand(16, 100, 64, 64)