# Is there record of a bosonic Stern-Gerlach measurement?

I cannot seem to find any peer-reviewed (or other) reference to an integer-spin Stern-Gerlach experiment. It shouldn't be too hard to do: just find you friendly neighbourhood Deuterium ion and shoot it through a Stern-Gerlach magnet.

Can one devise a photonic Stern-Gerlach experiment, i.e. spatial seperation of polarization states? One should also see only two states in this case, because the spin-0 photon state is "reserved" for EM-interactions (this might be too simple a statement, but this is how I understand it currently).

EDIT it seems some of you are misunderstanding the question: I am inquiring about a Stern-Gerlach-like experiment, where spin states have been split, and by extension the perpendicular nature of non-commuting measurements. So only the concept of the S-G experiment as extensively described in introductory QM textbooks such as Sakurai.

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Weeeeeird, I was thinking of this exact question only a few hours ago. For what it's worth, this discussion on Physics Forums draws an interesting parallel between Stern-Gerlach and birefringence. –  Richard Terrett Dec 4 '12 at 10:01
–  Ben Crowell Aug 28 '13 at 23:10

Photons are gauge bosons, they do not have spins or magnetic moments!

For electrons, bose/fermi atoms in a magnetic field, we have the energy $$E({\bf r})=\boldsymbol{\mu}\cdot {\bf B}({\bf r})$$ where $\boldsymbol{\mu}$ is the magnetic moment.

Hence we have force due to the gradient of magnetic field, $${\bf F}=-\nabla E({\bf r})=-\mu\nabla{B}({\bf r})$$ which produces Stern-Gerlach effect. You cannot write down a "photonic version" of this.

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Photons do have spin, but they don't have magnetic moments, because photons don't couple directly to photons. –  user1504 Dec 4 '12 at 14:28
In the literature, it is called orbital angular momentum or polarization but not spin. –  ChenChao Dec 4 '12 at 14:59
Not in the literature I read (e.g., most particle physics books). Anyways, as long as it's clear that photons are not spin 0 objects, we don't need to argue about terminology. –  user1504 Dec 4 '12 at 15:15
Yes, you are right. Gauge bosons are spin-1 particles. But I mean in the context of atomic physics, photon only transfer orbital angular momenta to electrons. It is an important notion. –  ChenChao Dec 4 '12 at 15:41
Of course Stern-Gerlach doesn't work on photons. But it does on deuterium, and the link by @Richard links to birefringence in crystals, which spatially separates photons per spin state. –  rubenvb Dec 4 '12 at 18:15