Subradiance and Selective Radiance in Atomic Arrays

22.02.2018, 11:00

Max Planck Institute for the Science of Light
, Genes Research Group

Mariona Moreno-Cardoner, ICFO (Institute of Photonic Science), Barcelona, Spain

Time, place:
Thursday, 22 February 2018, 11:00 h, Max Planck Institute for the Science of Light, Seminar Room A.1.500

Achieving controlled coherent interactions between photons and atomic media is a central goal in quantum optics, and essential for many applications in quantum information processing and quantum metrology. Spontaneous emission, in which photons are absorbed by atoms and then re-scattered into undesired channels poses a fundamental limitation in all these tasks. In typical theoretical treatments of atomic ensembles, it is assumed that this re-scattering occurs independently, and at a rate given by a single isolated atom, which in turn gives rise to standard limits of fidelity in applications such as quantum memories for light or photonic quantum gates. However, this assumption can be in fact dramatically violated. In particular, it has long been known that spontaneous emission of a collective atomic excitation can be significantly enhanced or suppressed through strong interference in emission between atoms — the physics of super- and sub-radiance. While these concepts are not new, the physics underlying these effects have not been completely understood. 

In this talk we will first discuss a theoretical framework that captures multiple scattering and interference of light while propagating through the atoms [1]. Using this formalism, we will then show how sub-radiant states in a periodic atomic chain acquire an elegant interpretation in terms of optical modes that are “guided” by the array, which only emit due to scattering from the boundaries of the finite system. Then, we will introduce the new concept of selective radiance. Whereas sub-radiant states experience a reduced coupling to all optical modes, selectively radiant states are tailored to simultaneously radiate efficiently into a desired channel and to suppress emission into undesired directions, thus enhancing the atom-light interface. We will show that these states naturally appear in chains of atoms coupled to nanophotonic structures. As a relevant application of how they can be exploited, we will show that selectively radiant states allow for a photon storage error that performs exponentially better with number of atoms than previously known bounds.

[1] A. Asenjo-Garcia, J. D. Hood, D. E. Chang, H. J. Kimble, Phys. Rev. A 95, 033818 (2017).

[2] A. Asenjo-Garcia, M. Moreno-Cardoner, A. Albrecht, H. J. Kimble, D. E. Chang, Phys. Rev. X 7, 031024 (2017).