How do I create expression tree for reading a value by array access for an IDictionary<string,object>?

I want to represent:

((IDictionary<string,object>)T)["Key Name"]

I can't find any example of ArrayAccess being used to access with string name. I want something like:

var parameterExpression = Expression.Parameter(typeof(IDictionary<string, object>));

var paramIndex = Expression.Constant("name");

var arrayAccess = Expression.ArrayAccess(parameterExpression, paramIndex);

I get error stating it is not an array. What is correct way to do this?