Chip-based Decelerators for Rydberg Atoms and Molecules

In this project, we develop chip-based devices, with which we decelerate and deflect beams of Rydberg atoms and molecules. Cold atoms and molecules in supersonic expansion are photoexcited to Rydberg states with principal quantum number n selected in the range between 20 and 50 in the presence of an electric field. As in Rydberg-Stark deceleration, the experiments exploit the fact that the electric dipole moments of Rydberg atoms and molecules scale with n as n2, and are thus very large. At n=30, they exceed 3000 Debye. The supersonic beam containing the Rydberg atoms or molecules are loaded into electrostatic traps generated by applying time-dependent electric potentials to series of electrodes located on the chip surface [1]. The time dependence of the electric potentials is precalculated so that the traps into which the Rydberg atoms or molecules are loaded are accelerated or decelerated above the chip surface. It is also possible to decelerate the traps to zero velocity and store the Rydberg atoms or molecules above the chip surface [2].

The ability to control the external degrees of freedom of Rydberg atoms or molecules with chip-based decelerators is a key ingredient of a new approach to investigate ion-neutral reactions at very low temperatures. To this aim, atoms or molecules in a supersonic expansion are excited to Rydberg states and deflected from the original propagation axis by 10° using a chip with a curved surface [3]. This allows us to merge the sample of excited atoms/molecules with a beam of ground-state atoms or molecules. The highly excited Rydberg electron acts in the collision as a spectator, which enables the study of ion-molecule reactions. The relative collision energy between the co-propagating beams can be adjusted by manipulating the longitudinal velocity of the Rydberg atom beam with the decelerator. Alternatively, the velocity of the beam of ground-state molecules can be modified by changing the temperature of the nozzle used to generate the supersonic expansion. The collision temperature is ultimately limited by the internal temperatures of the two beams, and can be as low as about 100 mK. Typical ion-molecule reactions we are interested in are reactions such as H2+ + H2  --> H3+ + H and D+ + H2 --> HD + H+, which are of fundamental importance in astrophysics.

The Rydberg-atom decelerators and traps are also developed as elements of a general strategy to fully control the translational and internal degrees of freedom of Rydberg atoms using chip-based devices with integrated coplanar microwave waveguides [4,5], for instance for quantum-optics experiments, as pursued in the realm of this project in a collaboration with the quantum-device laboratory of Prof. Wallraff in the Physics Department of ETH.

Chip Decelerator

[1] "A surface-electrode Rydberg-Stark decelerator"
S. D. Hogan, P. Allmendinger, H. Sassmannshausen, H. Schmutz, and F. Merkt, Phys. Rev. Lett. 108, 063008 (2012), doi: external page10.1103/PhysRevLett.108.063008

[2] "Deceleration and trapping of a fast supersonic beam of metastable helium atoms with a 44-electrode chip decelerator"
P. Allmendinger, J. A. Agner, H. Schmutz, and F. Merkt, Phys. Rev. A 88, 043433 (2013), doi: external page10.1103/PhysRevA.88.043433

[3] "Surface-electrode decelerator and deflector for Rydberg atoms and molecules"
P. Allmendinger, J. Deiglmayr, J. A. Agner, H. Schmutz, and F. Merkt, Phys. Rev. A 90, 043403 (2014), doi: external page10.1103/PhysRevA.90.043403

[4] "Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide"
S. D. Hogan, J. A. Agner, F. Merkt, T. Thiele, S. Filipp, and A. Wallraff, Phys. Rev. Lett. 108, 063004 (2012), doi: external page10.1103/PhysRevLett.108.063004

[5] "Manipulating Rydberg atoms close to surfaces at cryogenic temperatures"
T. Thiele, S. Filipp, J. A. Agner, H. Schmutz, J. Deiglmayr, M. Stammeier, P. Allmendinger, F. Merkt, and A. Wallraff, Phys. Rev. A 90, 013414 (2014), doi: external page10.1103/PhysRevA.90.013414

For further information, please contact us or learn more about our research by reading one of our Publications.

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