Entanglement Hypothesis by de Broglie in 1935

[genefalk]

I believe that it was de Broglie who hypothesized that two particles could become entangled and in 1935 Schrödinger gives it the name.

Can someone point me at the the publication in which de Broglie did his hypothesizing or at least tell me the year.

 

[VantagePoint72]

As far as I know, the first discussion about the possibility for what we now call entanglement was the EPR paper in 1935, which de Broglie had nothing to do with.

 

[ProPatto16]

I agree with LastOneStanding, fairly sure it was a 1935 paper on the EPR Paradox written by Einstein Podolsky and Rosen, hence EPR... since at the time they actually had no idea what they had discovered... and it was later the Schrödinger called it entanglement.

If you google search EPR Paradox 1935 and do some reading it shouldn't be that hard to find out what you want

 

[vanhees71]

As far as I know, Schrödinger coined the name "Verschränkung" (="Entanglement") when discussing philosophical implications of quantum theory with Einstein. His famous gedanken experiment with the cat also is closely related with entanglement. I'm not sure, whether he was before EPR.

 

[DevilsAvocado]

In the paper “Einstein, Podolsky, Rosen, and Shannon” Asher Peres writes:

[my bolding]

http://arxiv.org/abs/quant-ph/0310010]One[/PLAIN] day, I came into Rosen’s office, and I found him sorting out his papers. On the ground, there were cartons full of old reprints, with the characteristic green covers of The Physical Review. One of them read: “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” The authors were A. Einstein, B. Podolsky, and N. Rosen. I thought that this would be a nice item to have in my collection of reprints, and politely asked:

“Professor Rosen, may I take one of these reprints?”
He looked concerned.
“Ha, how many are left?”
We counted them, which was not difficult: there were two. Then he said, with some hesitation,
“Well, if there are two, you may have one.”
This is how I acquired the last available reprint of the famous article of Einstein, Podolsky, and Rosen.

Let us have a look at that wonderful paper. You will immediately notice that Eqs. (7) and (8) involve entangled wave-functions, and indeed the whole issue is about the physical consequences of such an entanglement. Entangled wave-functions were not new at that time: you can find one, for example, in Eq. (10) of Rosen’s 1931 seminal paper on the ground state of the hydrogen molecule [7], which is probably more famous among chemists than the EPR paper is among physicists.

Some time after that work, Rosen became a post-doc of Einstein at the Institute of Advanced Studies in Princeton. One day, at the traditional 3 o’clock tea, Rosen mentioned to Einstein a fundamental issue of interpretation related to entangled wave-functions. Einstein immediately saw the implications for his long standing disagreement with Bohr. As they discussed the problem, Boris Podolsky joined the conversation, and later proposed to write an article. Einstein acquiesced. When he later saw the text, he disliked the formal approach, but agreed to its publication. Then, as soon as the EPR article appeared, Podolsky released its contents to the New York Times (4 May 1935, page 11) in a way implying that the authors had found that quantum mechanics was faulty. This infuriated Einstein, who after that no longer spoke with Podolsky.


[7] N. Rosen, Phys. Rev. 38, 2099 (1931).

Peres talks about “entangled wave-functions” but the term wasn’t coined until after the 1935 EPR paper. In the “The Shaky Game” Arthur Fine writes:

Schrödinger continues by focusing on certain mathematical aspects of the EPR example. These have to do with the expansion of the state function of a composite system into a bilinear series of functions defined only on the component systems. He points out that the composite EPR case, after the interaction has effectively ceased, is a very exceptional one in this regard, for there all the coefficients of the bilinear expansion are identical. Schrödinger believes that the paradoxical feature of the EPR case (he calls it the "contradiction" [widerspruch]) does not depend on this exceptional identity of coefficients, but is already present in more general expansions, and he tries to outline to Einstein how this goes. In fact the preliminary analysis of the conditions for a contradiction outlined in this June 7 letter finds its way into the Naturwissenschaften article (hereafter NW) in section II of the final, December 13 installment. There Schrödinger (1935b, p. 844) calls attention to features of what he refers to as "entanglement" (Verschränkung); i.e., cases where after an interaction between two systems the state function of the composite system no longer factors into the product of component state functions. What is peculiar, according to Schrödinger, is that in these cases, quite generally, one can find two incompatible measurement procedures for one of the systems (corresponding to incompatible quantum observables for that system) each one of which would lead to a resolution of the entanglement by forcing out some definite state for the other system—regardless of what particular measured values actually turn up. Moreover, the states forced out for the unmeasured system would themselves be incompatible (i.e., there is no quantum probability of their joint occurrence). Thus, according to Schrödinger, what is paradoxical about EPR (to which he immediately turns in section 12 of NW) is common to various entangled systems and not just to the special EPR case.

Therefore it looks like "entanglement" was known [among chemists] before the 1935 EPR paper, but it was Einstein who saw the significance of the phenomena, and then Schrödinger the same year generalized it, coined the term, and stressed the overall importance for QM theory.


P.S. Verschränkung translated directly from German:
interleave
interconnection
folding
clasping
...

 

[DevilsAvocado]

... and this is why Einstein was upset ...

Credit: New York Times, 4 May 1935, p. 11
New York Times Archive

And who can blame him... the last line is sort of “overenthusiastic”...