Dipolar interactions are fundamentally different from the usual van der Waals forces in real gases.
anisotropy the dipolar interaction is nonlocal and as such allows for self
organized structure formation. Candidates for dipolar species are polar
molecules, Rydberg atoms and magnetic atoms. More than ten years ago the first
dipolar effects in a quantum gas were observed in an ultracold Chromium gas. By
the use of a Feshbach resonance a purely dipolar quantum gas was observed three
years after . By now dipolar interaction effects have been observed in
lattices and also for polar molecules. Recently it became possible to study
degenerate gases of lanthanide atoms among which one finds the most magnetic atoms.
The recent observation of their collisional properties includes the emergence
of quantum chaos and very broad resonances [2,3]. Similar to the Rosensweig
instability in classical magnetic ferrofluids self-organized structure formation
was expected. In our experiments with quantum gases of Dysprosium atoms we
could recently observe the formation of a droplet crystal . In contrast to
theoretical mean field based predictions the superfluid droplets did not
collapse. We find that this unexpected stability is due to beyond meanfield
quantum corrections of the Lee-Huang-Yang type [5,6]. We observe and study
self-bound droplets  which can interfere with each other. These droplets are
100 million times less dense than liquid helium droplets and open new
perspectives as a truly isolated quantum system.
 T. Lahaye, C.
Menotti, L. Santos, M. Lewenstein, and T. Pfau, "The physics of dipolar bosonic quantum gases", Rep.
Prog. Phys. 72, 126401 (2009)
 T. Maier, I.
Ferrier-Barbut, H. Kadau, M. Schmitt, M. Wenzel, C. Wink, T. Pfau, K.
Jachymski, P. S. Julienne, "Broad Feshbach
resonances in collisions of ultracold Dysprosium atoms", Phys. Rev. A 92, 060702(R) (2015)
Maier, H. Kadau, M. Schmitt, M. Wenzel, I. Ferrier-Barbut, T. Pfau, A. Frisch,
S. Baier, K. Aikawa, L. Chomaz, M. J. Mark, F. Ferlaino, C. Makrides, E.
Tiesinga, A. Petrov, S. Kotochigova, "Emergence
of chaotic scattering in ultracold Er and Dy",
Phys. Rev. X 5, 041029 (2015)
 H. Kadau, M.
Schmitt, M. Wenzel, C. Wink, T. Maier, I. Ferrier-Barbut, T. Pfau
"Observing the Rosensweig instability of
a quantum ferrofluid", Nature 530, 194 (2016)
 T. D. Lee, K. Huang, and C. N. Yang, " Eigenvalues and Eigenfunctions of a Bose System of
Hard Spheres and Its Low-Temperature Properties", Phys. Rev. 106, 1135 (1957). D.S. Petrov, “Quantum
mechanical stabilization of a collapsing Bose–Bose mixture”, Phys. Rev. Lett. 115, 155302 (2015).
 I. Ferrier-Barbut, H. Kadau, M. Schmitt, M. Wenzel, T. Pfau, "Observation of quantum droplets in a
strongly dipolar Bose gas", Phys. Rev. Lett. 116, 215301 (2016)
Schmitt, M. Wenzel, F. Böttcher, I. Ferrier-Barbut, and T. Pfau,
"Self-bound droplets of a dilute magnetic quantum liquid", Nature 539, 259 (2016)