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Cavity quantum electrodynamics with Carbon Nanotubes – NC2

Submission summary

Carbon nanotubes (CNTs) have emerged as original light emitters that trigger both fundamental and technological investigations due to intriguing properties : a large choice of bandgaps covering the telecom bands, low-cost production, extremely robust excitons leading to room temperature emission with possible electrical excitation. Most of these properties arise from the one-dimensional quantum confinement which gives rise to novel one-dimensional (1D) elementary excitations and strongly enhanced carrier interactions. Recent experimental breakthroughs have revealed original effects due to this unique geometry such as anomalous acoustic phonon–exciton coupling leading to non-Markovian decoherence, emission of antibunched photons and ultralong-lived excitons at low temperature... With the steady progress in production and post-processing, CNTs have now reached the maturity for advanced experiments in the spirit of those successfully developed for the previous generation of semiconducting nano-emitters with the specificity of showing electronic excitations ranging from 0D to 1D. In particular, recent breakthroughs in the control of the dephasing processes and the delocalization length of the excitons open the way to the implementation of original experiments in the context of cavity quantum electrodynamics (CQED). The key point is to achieve a drastic enhancement of the light-matter interaction by means of a tunable optical cavity. To this end, we propose a fully adjustable geometry based on fiber micro-cavities that is best suited for a thorough investigation of CQED effects in non-epitaxial nano-emitters. The specific properties of CNTs open the way to original effects in the two major CQED regimes :

(I) the weak coupling regime leading to the so-called Purcell effect with enhanced photon emission rate and single mode emission that could bring a real breakthrough in terms of source brightness with the ultimate goal of achieving a high efficiency tunable electrically-driven single-photon source in the Coulomb blockade regime.

(II) the strong coupling regime where the new eigenstates are polaritons -mixed photon-exciton states- that led to a wealth of new physical effects in the 2D geometry (e.g. polariton condensation or lasing) but that are essentially unexplored in the 1D geometry. In this regime, we thus expect original results, in particular due to the large Coulomb interactions that should result in huge polaritonic nonlinearities.

To this end, NC2 gathers complementary specialists of the photo-physics of CNTs (LPA), of micro-cavities and quantum information (LKB) and of the growth and transport properties of CNTs (NEEL).
The key point in NC2 is the design of a specific geometry that brings an unprecedented versatility for advanced studies. In fact, the fiber micro-cavities bring a built-in spectral and spatial matching to the emitter and an invaluable flexibility in the control of electromagnetic confinement allowing a thorough investigation of CQED effects as a function of the emitter's intrinsic properties. The beginning of the project relies on readily available matrix-embedded nanotubes, but ultimate effects are expected with vacuum suspended nanotubes that are free of any environment induced dephasing processes and that will be developed on purpose for this project.
Among all the possibilities offered by this geometry, we choose to highlight the cavity feeding effect that exploits the pure dephasing of solid-state emitters and that could pave the way to a tunable single photon source by dynamically pinning the emitter's frequency at the one of the cavity. In addition, with vacuum suspended nanotubes, the strongly reduced loss rates for the emitter together with the high finesse achievable with the fiber cavity should put the strong coupling regime at reach, unraveling a novel physics such as the one of 1D polaritons with strong interaction.

Project coordination

Christophe Voisin (Laboratoire Pierre Aigrain )

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LPA Laboratoire Pierre Aigrain
NEEL Institut Néel
LKB Laboratoire Kastler Brossel

Help of the ANR 504,956 euros
Beginning and duration of the scientific project: September 2015 - 42 Months

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