Abstract An ensemble of excited atoms can synchronize emission of light collectively in a process known as superradiance when its characteristic size is smaller than the wavelength of emitted photons. The underlying superradiance depends strongly on electromagnetic (photon) fields surrounding the atomic ensemble. High mode densities of microwave photons from 300 K blackbody radiation (BBR) significantly enhance decay rates of Rydberg states to neighbouring states, enabling superradiance that is not possible with bare vacuum induced spontaneous decay. Here we report observations of the superradiance of ultracold Rydberg atoms embedded in a bath of room-temperature photons. The temporal evolution of the Rydberg | nD ⟩ to |( n + 1) P ⟩ superradiant decay of Cs atoms ( n the principal quantum number) is measured directly in free space. Theoretical simulations confirm the BBR enhanced superradiance in large Rydberg ensembles. We demonstrate that the van der Waals interactions between Rydberg atoms change the superradiant dynamics and modify the scaling of the superradiance. In the presence of static electric fields, we find that the superradiance becomes slow, potentially due to many-body interaction induced dephasing. Our study provides insights into many-body dynamics of interacting atoms coupled to thermal BBR, and might open a route to the design of blackbody thermometry at microwave frequencies via collective, dissipative photon-atom interactions.Abstract An ensemble of excited atoms can synchronize emission of light collectively in a process known as superradiance when its characteristic size is smaller than the wavelength of emitted photons. The underlying superradiance depends strongly on electromagnetic (photon) fields surrounding the atomic ensemble. High mode densities of microwave photons from 300 K blackbody radiation (BBR) significantly enhance decay rates of Rydberg states to neighbouring states, enabling superradiance that is not possible with bare vacuum induced spontaneous decay. Here we report observations of the superradiance of ultracold Rydberg atoms embedded in a bath of room-temperature photons. The temporal evolution of the Rydberg | nD ⟩ to |( n + 1) P ⟩ superradiant decay of Cs atoms ( n the principal quantum number) is measured directly in free space. Theoretical simulations confirm the BBR enhanced superradiance in large Rydberg ensembles. We demonstrate that the van der Waals interactions between Rydberg atoms change the superradiant dynamics and modify the scaling of the superradiance. In the presence of static electric fields, we find that the superradiance becomes slow, potentially due to many-body interaction induced dephasing. Our study provides insights into many-body dynamics of interacting atoms coupled to thermal BBR, and might open a route to the design of blackbody thermometry at microwave frequencies via collective, dissipative photon-atom interactions.

arXiv:2009.12860New Journal of PhysicsJul 12, 202121 citations

Anticrossing Spectroscopy of Rydberg Atoms Using Blackbody Radiation

R. C. Stoneman, Thomas F. Gallagher

We report the observation of anticrossing signals arising from the interaction of 300-K blackbody radiation with Rydberg atoms near avoided crossings of Stark levels. The role of the blackbody radiation is roughly analogous to that of the resonance fluorescence in traditional anticrossing spectroscopy. We present preliminary results for avoided crossings of $\mathrm{ns}$ states with $n\ensuremath{-}2$ Stark states in potassium for $n$ in the range 18-21.We report the observation of anticrossing signals arising from the interaction of 300-K blackbody radiation with Rydberg atoms near avoided crossings of Stark levels. The role of the blackbody radiation is roughly analogous to that of the resonance fluorescence in traditional anticrossing spectroscopy. We present preliminary results for avoided crossings of $\mathrm{ns}$ states with $n\ensuremath{-}2$ Stark states in potassium for $n$ in the range 18-21.

Physical Review LettersDec 2, 198521 citations

Spectroscopy of Rydberg Atomic Systems in a Black-Body Radiation Field

Alexander V. Glushkov, Valentin B. Ternovsky, Anna A. Kuznetsova +1 more

Progress in theoretical chemistry and physicsJan 1, 20202 citations

Rydberg atom spectroscopy enabled by blackbody radiation ionization

Xiaoxu Lu, Yuan Sun, Harold J. Metcalf

We have excited helium atoms from their metastable 2 ${}^{3}\phantom{\rule{-0.16em}{0ex}}S$ state to Rydberg states in the range $13<n<50$ in a two-step process via the 3 ${}^{3}\phantom{\rule{-0.16em}{0ex}}P$ state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.We have excited helium atoms from their metastable 2 ${}^{3}\phantom{\rule{-0.16em}{0ex}}S$ state to Rydberg states in the range $13<n<50$ in a two-step process via the 3 ${}^{3}\phantom{\rule{-0.16em}{0ex}}P$ state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.

Physical Review ASep 6, 20116 citations

\mathrm{ns}

states with $n\ensuremath{-}2$ Stark states in potassium for

n

in the range 18-21.

We have excited helium atoms from their metastable 2

{}^{3}\phantom{\rule{-0.16em}{0ex}}S

state to Rydberg states in the range

13<n<50

in a two-step process via the 3

{}^{3}\phantom{\rule{-0.16em}{0ex}}P

state using light at $\ensuremath{\lambda}=389$ nm and 785--815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.