Coherent light-matter interfaces with highly-excited thermal atoms

TYPESolid State Institute Seminar
Speaker:Dr. Ran Finkelstein
Affiliation:Physics department, Weizmann Institute Rehovot
Time:12:30 - 13:30
Location:Solid State Auditorium(Entrance)
Remark:Host: Assistant Professor Yoav Sagi

Warm atomic vapors are known for their technical simplicity and potential scalability. However, despite these benefits,
motional dephasing limits the strength and coherence of the light-matter interaction, as compared with laser-cooled atoms. I
will present several schemes developed to realize strong, coherent, and faithful light-matter interaction at ambient conditions
and to overcome motional dephasing, towards effective photon-photon interaction. These schemes can be further applied to
various gas, solid and engineered systems hindered by inhomogeneous dephasing due to variations in time, space, or other
First, I will describe a new protocol for an arbitrarily fast, genuinely noise-free, quantum memory in rubidium vapor.
Employing a ladder level system of purely orbital transitions with nearly degenerate frequencies simultaneously enables high
bandwidth, low noise, and long memory lifetime [1]. Second, I will present a scheme for protecting a qubit or a collective
excitation from inhomogeneous dephasing. The scheme relies on
continuously dressing the qubit with an auxiliary sensor
state which exhibits an opposite and potentially enhanced sensitivity to the same source of inhomogeneity. We focus on
motional dephasing of a spin-wave in an atomic ensemble. By employing a two-tone dressing field, we demonstrate
complete suppression of inhomogeneous dephasing as well as immunity to drive noise [2]. In related works with continuouswave spectroscopy, we demonstrate the enhancement and narrowing of spectral lines [3,4]. Finally, I will also present our
effort to realize a unique optical mode by tapering down an optical fiber to the deep sub-wavelength scale. This leads to a
drastic expansion of the evanescent field to over 10 times the optical wavelength, compatible with typical dimensions of the
Rydberg blockade. When interfaced with atomic vapor, this configuration balances tight confinement, long atomic
interaction times, and negligible surface interactions [5].
1] R. Finkelstein, E. Poem, O. Michel, O. Lahad, and O. Firstenberg, "Fast, noise-free memory for photon synchronization at room temperature",
Science Advances 4 (2018).
[2] R. Finkelstein, O. Lahad, I. Cohen, O. Davidson, E. Poem, and O. Firstenberg, “Continuous protection of a collective state from inhomogeneous
dephasing”, Physical Review X 11 (2021) .
[3] O. Lahad, R. Finkelstein, O. Davidson, O. Michel, E. Poem, and O. Firstenberg, “Recovering the homogeneous absorption of inhomogeneous
media”, Physical Review Letters 123 (2019) .
[4] R. Finkelstein, O. Lahad, O. Michel, O. Davidson, E. Poem, and O. Firstenberg, “Power narrowing: Counteracting Doppler broadening in two-color
transitions”, New Journal of Physics 21 (2019) .
[5] R. Finkelstein, G. Winer, D. Z. Koplovich, O. Arenfrid, T. Hoinkes, G. Guendelman, M. Netser, E. Poem, A. Rauschenbeutel, B. Dayan, and O.
Firstenberg “Super-extended nanofiber-guided field for coherent interaction with hot atoms”, Optica 8 (2021)

The lecture will take place in the hybrid format-see the seminar note,
in the Solid State Auditorium and via zoom