Pardon my ignorance, but would it be possible to use X-rays to read the contents of memory? Say, in a TPM or Secure Enclave? I feel like if you had an accurate enough beam you could detect if a memory cell is "charged" or not.
I'm not sure about whether you can do that with x-rays, however you might find this paper interesting - 'Reverse engineering Flash EEPROM memories using Scanning Electron Microscopy' -
http://www.cl.cam.ac.uk/~sps32/cardis2016_sem.pdf
I'm far from an expert on the subject but as far as I know you can only see the structure of the chip (how the transistors are wired together, basically), not the current state of the logic. So you can use this to dump a hardwired ROM but not dynamic content.
