QuCoLiMa Talk – Amita Deb – Optical response of a quantum degenerate gas
Date: November 28, 2023Time: 12:00 pm – 1:00 pmLocation: On-site in Mainz and livestream via Zoom
Amita Deb - University of Birmingham
Optical response of a quantum degenerate gas
I will report our measurements on the interaction of off-resonant light with ultracold ensembles of fermionic atoms . For Fermi gases of potassium atoms in the quantum degenerate regime, we observe a marked suppression in light scattering and enhancement of transmission of light as compared to a similarly prepared thermal Bose gas of rubidium atoms. We attribute these observations to Pauli blocking, where Fermi-Dirac statistics causes atoms to occupy a large region of the momentum space and thereby limits the number of accessible states for a scattering atom. While Pauli blocking suppress the scattering of light out of a probe laser beam mode, a largely unmodified dispersive light-matter interaction is predicted and we verify this experimentally by measuring the phase shift of transmitted light. I will discuss two theoretical approaches which explain these results, one based on the Fermi golden rule  and another based on the coherent optical response of quantum gases . Our work confirms a longstanding theoretical result in the theory of the optical response of quantum gases. Independent experiments from JILA and MIT groups have also reported suppression of incoherently scattered photons from Fermi gases of strontium  and lithium , and I will discuss these experiments. Our measurements also showed enhanced scattering near the critical temperature of a Bose gas which was later confirmed as Bosonic enhancement of light scattering by experiments in MIT .
 A.B. Deb and N. Kjærgaard. Observation of Pauli blocking in light scattering from quantum degenerate fermions. Science 374, 972 (2021).
 B. DeMarco and D. S. Jin, Exploring a quantum degenerate gas of fermionic atoms. Phys. Rev. A 58, R4267 (1998).
 O. Morice, Y. Castin and J. Dalibard, Refractive index of a dilute Bose gas. Phys. Rev. A 51, 3896–3901 (1995).
 C. Sanner Lindsay Sonderhouse, Ross B. Hutson, Lingfeng Yan, William R. Milner and Jun Ye, Pauli blocking of atom-light scattering. Science 374, 979 (2021).
 Y. Margalit, Y. Lu, F. C. Top and W. Ketterle, Pauli blocking of light scattering in degenerate fermions. Science 374, 976 (2021).
 Y.-K. Lu, Y. Margalit and W. Ketterle, Bosonic stimulation of atom-light scattering in an ultracold gas. Nature Physics 19, 210 (2023).
All talks hybrid:
Mixture of on-site talks at the main sites of QuCoLiMa (Erlangen, Mainz, Saarbrücken) as well as online talks. Regardless of where the talks are given, they are livestreamed via Zoom and can be watched from home/office or cooperatively in the following meeting rooms:
- Erlangen: Livestream/Presentation in Lecture hall HF + open sandwiches in the foyer afterwards
- Saarbrücken: Livestream/Presentation in tba
- Mainz: Livestream/Presentation in tba
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QuCoLiMa Talks are regular seminars of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter), where (external) experts are invited to present their work.
More information at http://www.qucolima.de/talks
On-site in Mainz and livestream via Zoom