Seems to me that fusion could be achieved on an atom-by-atom basis if you used a super intense magnetic field, 500k gauss, to squeeze two hydrogen atoms together so that they fuse..........................
AFAIK, no macro apparatus exists that allows this to be done. Lattice confinement appears to be the closest tech we have.
The trick is to treat the math on a one-to-one basis, such as in a Luttinger Liquid and set up a linear Bose-Einstein Condensate.
Hence my Vibrating 1Dimensional Luttinger Liquid Bose-Einstein Condensate [V1DLLBEC] theory.
https://www.google.com/search?q=v1dllbec&sxsrf=ALeKk01WopxshkmIzgjW9pdOsxOQXKzDZA%3A1625177521689&source=hp&ei=sT3eYNmSJ4nGsQXyz7O4AQ&oq=v1dllbec&gs_lcp=ChFtb2JpbGUtZ3dzLXdpei1ocBADMgQIIxAnMgQIIxAnOgcIIxDqAhAnOg0ILhDHARCjAhDqAhAnOg0ILhDHARCvARDqAhAnOg4ILhCxAxCDARDHARCjAjoLCC4QsQMQxwEQowI6BQgAELEDOgIIADoECAAQDToGCAAQDRAeOggIABAIEA0QHjoKCAAQCBANEAoQHjoKCC4QxwEQrwEQDVChvgFY8toBYJnxAWgBcAB4AIAB6AGIAcIKkgEFMC42LjKYAQCgAQGwAQ8&sclient=mobile-gws-wiz-hp