Prof. Francis RobicheauxI've been a
professor of physics at Purdue University since 2013 (previously at
Auburn University 19932013). My research area is Theoretical Atomic
Physics, focusing on coherence and decoherence in quantum
systems, many body processes when photons interact with many atoms,
highly
excited (Rydberg) atoms, strong fields, and
ultracold plasmas. My group typically consists of undergrads,
grad students, and postdocs. I'm a member of the ALPHA collaboration:
the first group to trap the antimatter version of the Hydrogen atom and
the only group to quantitatively measure its properties.


Levitated NanoparticlesThis project was initiated because of experiments at Purdue performed in Tongcang Li's laboratory. One of their series of experiments focusses on the spinoptomechanics of levitated nanoparticles. We have been exploring how to simulate this system at the classical level (when the nanoparticle is hot enough to ignore quantum effects) and at the quantum level (where we have to understand the role of decoherence from various sources and feedback from measurements).Thai M. Hoang, Yue Ma, Jonghoon Ahn, Jaehoon Bang, F. Robicheaux, ZhangQi Yin, and Tongcang Li, "Torsional Optomechanics of a Levitated Nonspherical Nanoparticle," Phys. Rev. Lett. 117, 123604 (2016). PDF (810 kB) News and commentary This paper presented the first experimental results investigating the torsional vibrational motion of an asymmetric nanoparticle levitated in a laser beam. The librational motion occurs because the polarizability of an asymmetric nanoparticle can be much longer along its large axis than its short axis. This leads to a restoring torque that can give vibrational frequencies in the MHz regime T. Seberson and F. Robicheaux, "Parametric feedback cooling of rigid body nanodumbbells in levitated optomechanics," Phys. Rev. A 99, 013821 (2019). PDF (822 kB) We had performed calculations of cooling of simply vibrating motions. This paper was the first to investigate the cooling of a nanoparticle where the rotations about all of the axis are important. We found that the rotation about the symmetry axis qualitatively affects the possibility for cooling all of the librational motions. We also found that this rotation leads to equations of motion identical to a charged particle in a 2D harmonic oscillator plus a constant magnetic field. Five Other Recent Publications
Jaehoon Bang, T. Seberson, Peng Ju, Jonghoon Ahn, Zhujing Xu, Xingyu Gao, F. Robicheaux, and Tongcang Li, "Fivedimensional cooling and nonlinear dynamics of an optically levitated nanodumbbell," Phys. Rev. Research 2, 043054 (2020). PDF (1140 kB) T. Seberson and F. Robicheaux, "Distribution of laser shotnoise energy delivered to a levitated nanoparticle," Phys. Rev. A 102, 033505 (2020). PDF (953 kB) Changchun Zhong and F. Robicheaux, "Shotnoisedominant regime for ellipsoidal nanoparticles in a linearly polarized beam," Phys. Rev. A 95, 053421 (2017). PDF (934 kB) F. Robicheaux, "Comment on "MatterWave Interferometry of a Levitated Thermal NanoOscillator Induced and Probed by a Spin"," Phys. Rev. Lett. 118, 108901 (2017). PDF (58 kB) Changchun Zhong and F. Robicheaux, "Decoherence of rotational degrees of freedom," Phys. Rev. A 94, 052109 (2016). PDF (1220 kB) 
robichf[at]purdue.edu Links: 