I remember having read a statement, I think by one of the founding fathers of quantum mechanics, that we will probably never be able to control (or manipulate or see or isolate...?) a single quantum system (or atom).

The quote was used to highlight the fast progress experimental quantum physics has made over the last few decades (seeing that single-particle control is routinely achieved in experiments).

Does anyone know the quote and its source?

  • $\begingroup$ "The Founding Fathers" sounds religious... $\endgroup$ Commented Aug 10, 2021 at 22:17

1 Answer 1


Found it:

"[...] we never experiment with just one electron or atom or (small) molecule. In thought-experiments we sometimes assume that we do; this invariably entails ridiculous consequences [...]"

In: Schrödinger, E. (1952). Are There Quantum Jumps? Part II. The British Journal for the Philosophy of Science, 3(11), 233-242. Retrieved August 9, 2021, from http://www.jstor.org/stable/685266

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    $\begingroup$ I didn't look for such a quote, but if I had, I would have dismissed anything written in 1952 (and probably anything after about 1935), since you said "early 20th century". $\endgroup$ Commented Aug 9, 2021 at 15:36
  • $\begingroup$ How did you find it? How wrong he was. Why did he think that? $\endgroup$ Commented Aug 10, 2021 at 22:19
  • $\begingroup$ @DaveLRenfro: right, should have said early or mid 20th century. Didn't believe it to be so late, though, which makes the quote all the more interesting (for me). $\endgroup$ Commented Aug 11, 2021 at 11:19
  • $\begingroup$ @DescheleSchilder: you probably didn't notice that I answered my own quesiton? :D I found the quote by going through some of the texts on the topic I remember having read. And I thought the quote to be of earlier origin because, for example, the use of ion traps started already in the 1950s. (Ion traps are one of the work horses of quantum optics and quantum information, with which full quantum control over particles is routinely achieved nowadays.) $\endgroup$ Commented Aug 11, 2021 at 11:30

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