Quantum nanophotonics: controlling light with a sinle quantum dot (Prof. E. Waks)

Nanophotonic devices enhance light-matter interactions by confining photons to small mode volumes, enabling optical information processing at low energies.  In the strong coupling regime, these interactions are sufficiently large that a single photon creates a nonlinear response in a single atomic system. Such single-photon nonlinearities are highly desirable 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 and coherently control 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. By embedding them in a photonic crystal cavity that spatially confines light to less than a cubic wavelength we can attain the strong coupling regime. This device platform provides a pathway towards compact integrated quantum devices on a semiconductor chip that could serve as 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 atom-photon interactions on picosecond timescales in order to tailor quantum states of light in a cavity [2]. I will conclude with a discussion of the future prospects of this technology for developing complete integrated quantum systems on-a-chip.

References
[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).