use 2 private keys to encrypt content that could not be accessed by single key owner

Question

I need to provide a security mechanism like one used in the "2-key nuke button" of nuclear submarines movies :D.

I need to encrypt files that no-one could decrypt, neighter the one owning one of the encryption keys.

Content could be decrypted only with the acnowlodge of both the signers.

Is that possible with pgp or other known algorithms?

Thanks.