The TIP experiment

current grad student: Michael Viray

former grad students: Andrew Schwarzkopf, Nithiwadee Thaicharoen, Stephanie Miller

Photo of Tip and electrodes.

Photo of tip and surrounding electrodes. The tip/needle (visible through the electrode window) is the key component of the imaging system, and gives the experiment its name. The electrodes give us electric field control in the sample volume.


We would like to study spatial structures in cold rubidium.

The TIP (tip imaging probe) is a needle-shaped electrode that can produce a strong radial electric field. When combined with a micro-channel plate (MCP), it can produce spatially resolved ion images.

The first set of experiments with this setup studied Rydberg atoms. We observed spatial correlations, made measurements of the dipole blockade, and measured the strength of van der Waals interactions in Rydberg atom systems

The TIP is currently being used to study structures in expanding cold plasmas. So far we have observed shock fronts and nearest-neighbor ion correlations, and more plasma experiments are on their way.

The imaging system could be used to study other spatial structures as well. For example, we could also look at:


2020: We have a paper:
Michael A. Viray, Stephanie A. Miller, and Georg Raithel, "Coulomb expansion of a cold non-neutral rubidium plasma," Phys. Rev. A 102, 033303 (2020)

2019: TIP-1 decommissioned:
The original tip is removed from its vacuum chamber to make way for the ball lens MOT project. The tip is still functional and may be reinstalled in the future.

2018: Plasma formation:
Plasma is formed and imaged for the first time in the TIP-2 chamber.

2015: New TIP chamber:
Construction of the second tip chamber, TIP-2 (also known as BEC-2), is complete. This new tip is on an actuator and can be moved with respect to the MOT.

2013: We have a paper:
A. Schwarzkopf, D. A. Anderson, N. Thaicharoen, and G. Raithel, "Spatial correlations between Rydberg atoms in an optical dipole trap," Phys. Rev. A 88, 061406(R) (2013)

2011: We have a paper:
A. Schwarzkopf, R. E. Sapiro, and G. Raithel, "Imaging Spatial Correlations of Rydberg Excitations in Cold Atom Clouds," PRL 107, no. 10 (2011): 103001.

2012: We are now working to get higher magnification in the setup, to see smaller structures. We might see Coulomb effects between ions (upon ionization of the Rydberg atoms) and perhaps Rydberg crystals.


A reasonable introduction to the experiment can be found on our 2010 DAMOP poster. (DAMOP is "Division of Atomic Molecular and Optical Physics", our yearly division conference.)

DAMOP posters from various years:

More detail about the scientific background of this experiment can be found in the writeup for my prelim examination. This document also includes references to the literature, and some more recent data.

A copy of my slides and notes for the presentation are below. The slides have more details on the references (figures, in particular).


A few previous graduate students in the Raithel lab designed and built the beginnings of the apparatus. My thanks to them for getting the project started. To my knowledge, here's what they did:

Brenton Knuffman:

Rachel Sapiro:

Stephanie Miller:

Webpage author: Michael Viray
Last updated: Sept 10, 2019