Quantum Optics with Anderson Localized-Modes in Random Media – University of Copenhagen

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Quantum Photonics > Research > Anderson Localization

28 November 2011

Quantum Optics with Anderson Localized-Modes in Random Media

Enhancing the interaction between light and matter is the essence of many research disciplines including quantum information science, energy harvesting, and sensing.

Figure: Spectral signature of Anderson localization of light in a disordered photonic crystal waveguide: sharp optical resonances appear, randomly distributed in space and frequency along the waveguide.

The traditional way has been to strongly confine light in, e.g., a highly ordered resonator. Surprisingly, an alternative approach to confinement of waves exists, which was originally proposed by Philip Anderson in 1958, for which he was awarded the Nobel Prize in physics. In this approach, disordered materials are employed and for a certain amount of randomness of the structures, localized modes form spontaneously. Since then, the truly multidisciplinary research field of multiple scattering and Anderson localization has flourished merging otherwise distinct areas such as photonics, electron transport, acoustics, and seismology. Despite the progress, Anderson localization of optical waves has appeared difficult to achieve and applications of the effects have been lacking. We have demonstrated experimentally that disordered photonic crystal waveguides are very well suited for realizing Anderson-localized modes and employ them to dramatically enhance light-matter interaction [2].

By coupling a single quantum dot to the Anderson-localized mode, we demonstrate a whole new approach to cavity quantum electrodynamics employing fabrication disorder in photonic crystals as a resource rather than a nuisance, which is the traditional view. These results open the path to the design of novel quantum information devices that are controlled by disorder and are therefore inherently robust to unavoidable fabrication imperfections [3,4].  

Confirming Anderson localization experimentally is a major challenge because any optical loss in the system, for example absorption or scattering out of the structure, also results in an exponential decay of the intensity. This can be circumvented with our approach to efficiently excite Anderson-localized modes by employing the light emission from quantum dots embedded in the disordered nanostructure. We record the spatial and spectral intensity fluctuations of the Anderson localized modes, and by analyzing the quality (Q) factor distributions of the modes we extract important information on the localization length and average loss length. 

 [1] L. Sapienza, H. Thyrrestrup, S. Stobbe, P.D. Garcia, S. Smolka, and P. Lodahl, Cavity quantum electrodynamics with Anderson-localized modes, Science 327, 1352 (2010).

[2] L. Grossman, For quantum computer, add a dash of disorder, ScienceNews (March 2010).

[3] C. Barras, Shoddy construction beats precision in quantum world, NewScientist (March 2010).

[4] S. Smolka, H. Thyrrestrup, L. Sapienza, T. B. Lehmann, K. R. Rix, L. S. Froufe-Pérez, P. D. García,and P.Lodahl, Probing statistical properties of Anderson localization with quantum emitters
New J. Phys. 13, 063044 (2011).