@article {2568, title = {On-demand indistinguishable single photons from an efficient and pure source based on a Rydberg ensemble}, year = {2020}, month = {3/4/2020}, abstract = {

Single photons coupled to atomic systems have shown to be a promising platform for developing quantum technologies. Yet a bright on-demand, highly pure and highly indistinguishable single-photon source compatible with atomic platforms is lacking. In this work, we demonstrate such a source based on a strongly interacting Rydberg system. The large optical nonlinearities in a blockaded Rydberg ensemble convert coherent light into a single-collective excitation that can be coherently retrieved as a quantum field. We observe a single-transverse-mode efficiency up to 0.18(2), g(2)=2.0(1.5)\×10\−4, and indistinguishability of 0.982(7), making this system promising for scalable quantum information applications. Accounting for losses, we infer a generation probability up to 0.40(4). Furthermore, we investigate the effects of contaminant Rydberg excitations on the source efficiency. Finally, we introduce metrics to benchmark the performance of on-demand single-photon sources.\ 

}, url = {https://arxiv.org/abs/2003.02202}, author = {Dalia P. Ornelas-Huerta and Alexander N. Craddock and Elizabeth A. Goldschmidt and Andrew J. Hachtel and Yidan Wang and P. Bienias and Alexey V. Gorshkov and Steve L. Rolston and James V. Porto} } @article {2365, title = {Heisenberg-Scaling Measurement Protocol for Analytic Functions with Quantum Sensor Networks}, journal = {Phys. Rev. A}, volume = {100}, year = {2019}, month = {10/7/2019}, abstract = {

We generalize past work on quantum sensor networks to show that, for d input parameters, entanglement can yield a factor O(d) improvement in mean squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator. We outline a few potential applications, including calibration of laser operations in trapped ion quantum computing.

}, doi = {https://doi.org/10.1103/PhysRevA.100.042304}, url = {https://arxiv.org/abs/1901.09042}, author = {Kevin Qian and Zachary Eldredge and Wenchao Ge and Guido Pagano and Christopher Monroe and James V. Porto and Alexey V. Gorshkov} } @article {2141, title = {Dark state optical lattice with sub-wavelength spatial structure}, journal = {Phys. Rev. Lett.}, volume = {120}, year = {2018}, month = {2018/02/20}, pages = {083601}, abstract = {

We report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10\ nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44\ ms, nearly\ 105times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

}, doi = {10.1103/PhysRevLett.120.083601}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.120.083601}, author = {Yang Wang and Sarthak Subhankar and Przemyslaw Bienias and Mateusz Lacki and Tsz-Chun Tsui and Mikhail A. Baranov and Alexey V. Gorshkov and Peter Zoller and James V. Porto and Steven L. Rolston} } @article {2142, title = {Dissipation induced dipole blockade and anti-blockade in driven Rydberg systems}, journal = {Phys. Rev. A}, volume = {97}, year = {2018}, month = {2018/02/28}, pages = {023424}, abstract = {

We study theoretically and experimentally the competing blockade and antiblockade effects induced by spontaneously generated contaminant Rydberg atoms in driven Rydberg systems. These contaminant atoms provide a source of strong dipole-dipole interactions and play a crucial role in the system\&$\#$39;s behavior. We study this problem theoretically using two different approaches. The first is a cumulant expansion approximation, in which we ignore third-order and higher connected correlations. Using this approach for the case of resonant drive, a many-body blockade radius picture arises, and we find qualitative agreement with previous experimental results. We further predict that as the atomic density is increased, the Rydberg population\&$\#$39;s dependence on Rabi frequency will transition from quadratic to linear dependence at lower Rabi frequencies. We study this behavior experimentally by observing this crossover at two different atomic densities. We confirm that the larger density system has a smaller crossover Rabi frequency than the smaller density system. The second theoretical approach is a set of phenomenological inhomogeneous rate equations. We compare the results of our rate-equation model to the experimental observations [E. A. Goldschmidt\ et al.,\ Phys. Rev. Lett.116, 113001 (2016)] and find that these rate equations provide quantitatively good scaling behavior of the steady-state Rydberg population for both resonant and off-resonant drives.

}, doi = {10.1103/PhysRevA.97.023424}, url = {https://link.aps.org/doi/10.1103/PhysRevA.97.023424}, author = {Jeremy T. Young and Thomas Boulier and Eric Magnan and Elizabeth A. Goldschmidt and Ryan M. Wilson and Steven L. Rolston and James V. Porto and Alexey V. Gorshkov} }