Quantum nanophotonics: coupling single quantum dots to photons on-a-chip

Interactions between light and matter lie at the heart of optical communication and information technology. Nanophotonic devices can enhance light-matter interactions by confining photons to small mode volumes, which enables optical information processing at extremely low energies.  In the strong coupling regime, these interactions are sufficiently large that a single photon creates a nonlinear response in a single atom.  Such single-photon nonlinearities are critical for quantum information processing applications where atoms serve as quantum memories and photons act as carriers of quantum information.  In this talk I will discuss our effort to develop strongly coupled nanophotonic devices using quantum dots coupled to photonic crystals.  Quantum dots are semiconductor “artificial atoms” that can act as efficient photon emitters and stable quantum memories.  Using photonic crystals that confine light to mode volumes below a cubic wavelength, a single quantum dot can enter the strong strong coupling regime.  This device platform provides a promising pathway towards compact integrated quantum devices on a semiconductor chip that could serve as the basic components of quantum networks and distributed quantum computers.  I will discuss our demonstration of a quantum transistor, where a single spin in a quantum dot conditionally switches the state of a photon [1].  I will then describe our effort to coherently control light-matter interactions at the single photon level and tailor quantum states of light in a cavity [2].  Finally, I will conclude with a discussion of the future prospects of this technology for developing complete quantum systems on-a-chip that include sources, photonic circuits, and detectors.

[1]            H. Kim, R. Bose, T. C. Shen, G. S. Solomon, and E. Waks, Nat Photon 7, 373 (2013).

[2]            R. Bose, T. Cai, K. R. Choudhury, G. S. Solomon, and E. Waks, Nat Photon 8, 858 (2014).