Talk on "Atom Interferometry: Gravity, Blackbody Radiation and Chameleons"

08.11.2018 11:30 - 12:30

by Philipp Haslinger, TU Wien

If dark energy, which drives the accelerated expansion of the universe, consists of a light scalar field it might be detectable as a “fifth force” between normal-matter objects. In order to be consistent with cosmological observations and laboratory experiments, some leading theories use a screening mechanism to suppress this interaction. However, atom-interferometry presents a tool to reduce this screening1 on so-called chameleon models2. By sensing the gravitational acceleration of a 0.19 kg in vacuum source mass which is 10-9 times weaker than Earth´s gravity, we reached a natural bound for cosmological motivated scalar field theories and were able to place tight constraints3,4

Blackbody (thermal) radiation is emitted by objects at finite temperature with an outward energy-momentum flow, which exerts an outward radiation pressure. At room temperature e. g. a cesium atom scatters on average less than one of these blackbody radiation photons every 108 years.  Thus, it is generally assumed that any scattering force exerted on atoms by such radiation is negligible. However, particles also interact coherently with the thermal electromagnetic field5 and this leads to a surprisingly strong force acting in the opposite direction of the radiation pressure6.


[1]         C. Burrage, E.J. Copeland, E.A. Hinds, Probing dark energy with atom interferometry, J. Cosmol. Astropart. Phys. 2015 (2015) 042–042. doi:10.1088/1475-7516/2015/03/042.

[2]         B. Elder, J. Khoury, P. Haslinger, M. Jaffe, H. Müller, P. Hamilton, Chameleon dark energy and atom interferometry, Phys. Rev. D. 94 (2016) 044051. doi:10.1103/PhysRevD.94.044051.

[3]         P. Hamilton, M. Jaffe, P. Haslinger, Q. Simmons, H. Müller, J. Khoury, Atom-interferometry constraints on dark energy, Science. 349 (2015) 849–851. doi:10.1126/science.aaa8883.

[4]         M. Jaffe, P. Haslinger, V. Xu, P. Hamilton, A. Upadhye, B. Elder, J. Khoury, H. Müller, Testing sub-gravitational forces on atoms from a miniature, in-vacuum source mass, Nat. Phys. 13 (2017) 938–942. doi:10.1038/nphys4189.

[5]         M. Sonnleitner, M. Ritsch-Marte, H. Ritsch, Attractive Optical Forces from Blackbody Radiation, Phys. Rev. Lett. 111 (2013) 023601. doi:10.1103/PhysRevLett.111.023601.

[6]         P. Haslinger, M. Jaffe, V. Xu, O. Schwartz, M. Sonnleitner, M. Ritsch-Marte, H. Ritsch, H. Müller, Attractive force on atoms due to blackbody radiation, Nat. Phys. 14 (2018) 257–260. doi:10.1038/s41567-017-0004-9.


Host: M. Aspelmeyer

Seminarraum 3, 3. Stock, Boltzmanngasse 5, 1090 Wien