To expand a matrix with zeros in MATLAB, you can use the built-in function padarray.

Here's an example:

Suppose you have a 2x2 matrix A: 

A = [1 2; 3 4];

And you want to expand it to a 4x4 matrix by adding zeros around it. To do this, you can use the padarray function like this: 

B = padarray(A,[1 1],'both')

The first argument of padarray is the matrix you want to pad, and the second argument specifies the amount of padding you want to add on each side. In this case, we want to add one row and one column of padding on both sides, so we specify [1 1].

The third argument of padarray specifies how to add the padding. In this case, we're using the 'both' option to add padding on both sides.

The resulting matrix B will be: 

B =
     0     0     0     0
     0     1     2     0
     0     3     4     0
     0     0     0     0

Note that the original matrix A is surrounded by zeros on all sides.