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Room Temperature Quantum Dot Photonics |
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Written by Ilya Fushman
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Saturday, 13 January 2007 |
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In this project we are pursuing a efficient Single Photon Source (SPS) for quantum information applications at room temperature. To this end, we are combining colloidal (CdSe, PbS, PbSe) quantum dots with photonic crystal cavities in a variety of materials (e.g. SiN, GaAs, AlGaAs, Si). The cavity serves to enhance the rate of photon emission, the efficiency of photon collection and identicity of the emitted photons. On the left you see spectra of PbS quantum dots coupled to a Photonic Crystal Cavity. The cavity is shown below.
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On the left you see an SEM of a Photonic Crystal Cavity for integration with Colloidal Quantum dots. The E field intensity is shown on the right in a Finite Difference Time Domain (FDTD) simulation.
HERE is our current result on combining colloidal dots with cavities: A review of the role of cavities in SPS and QED applications can be found HERE. We are also interested in the “Many Photon” limit of operation, for making LED’s and lasers
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Single photons are important for a variety of applications including unconditionally secure communication, and potentially Quantum Computing. To date, the most robust and appealing single photon sources are single atoms, semiconductor quantum dots operating at cryogenic temperatures, and nitrogen vacancy centers in diamond. These all have downsides for a scaleable and marketable SPS for communication. Atomic sources require costly complicated optical setups, as do cryogenic temperatures. NV centers operate at wavelengths around 600-700 nm in the visible, and are poorly compatible with standard semiconductor device materials or transmission of light over long distances in fibers. Colloidal quantum dots, which have their own limitations due to shelved states and long lifetimes, operate at room temperature and can be tailored to cover wavelengths from the UV to the IR. Their fabrication and properties are bound to improve with time.
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Last Updated ( Tuesday, 14 August 2007 )
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