What cryptographic capability makes sure that even if the server's private key is compromised, the session keys will NOT be compromised?

Perfect forward secrecy (PFS) is used to change keys used to encrypt and decrypt data, ensuring that even if a compromise occurs, only a very small amount of data will be exposed. Symmetric encryption uses a single key. Quantum key rotation and Diffie-Hellman key modulation are both terms made up for this question.