I will talk about Counting rational points on determinant surfaces $ad-bc =1$ using Analytic Number Theory approach. This problem is directly related to the shifted convolution sum of the restricted divisor function $\tau_X(n)$. Our method also allows us to restrict up to two of the entries to be primes.
Links:
[1] https://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] https://www.mpim-bonn.mpg.de/node/3444
[3] https://www.mpim-bonn.mpg.de/node/158