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Welcome to NMDL!

     We are a multi-disciplinary group driven by curiosity and testable ideas that draw upon multiple traditional disciplines ranging from physics, chemistry, materials science, biochemistry, biology (cell and molecular), applied math, scientific computation / simulations, and biomedical, chemical, and electrical engineering to investigate some of the most challenging inter-disciplinary issues involving semiconductor materials and devices.

     Currently, our focus is on realizing on-chip scalable integrated quantum nanophotonic systems. As evident, "quantum" nanophotonic systems exploit the rules of quantum mechanics for information sensing, imaging, communication, and processing beyond what laws of classical physics allow. Targeted areas of applications range from quantum imaging (i.e. spatial resolution determined by the Heisenberg uncertainty principle), metrology, quantum repeaters for long-distance secure communication, and quantum computing.

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Current Focus: A paradigm for quantum optical circuits

     The long-sought goal of on-chip integrated solid-state quantum photonic systems for information processing continues to be elusive owing to the lack of a platform comprising spatially-ordered arrays of on-demand single photon sources of adequate photon emission characteristics buried in a matrix with planar surface (see schematic). To this end, we have taken a major step forward by exploiting an approach to spatially-selective synthesis of semiconductor single quantum dots that holds considerable promise for addressing the challenge as captured in the different panels of Figure 1.

Figure 1 (a) SEM image of an ordered array of pyramidal shaped structures containing single quantum dot (red region in the schematic) residing on the top of mesa of a reduced targeted size during material deposition from the starting square nanomesa (single image), resulting in the final pyramidal shape (SEM image)); (b) Emitted photon wavelength distribution from a 5X8 array- displayed color-coded and as histogram- revealing an unprecedented uniformity of < 2nm and, strikingly, pairs with emission within 0.2nm; (c) An illustrative photoluminescence from spontaneous decay of a neutral exciton; (d) Two photon coincidence count versus time between the count for pulsed excitation showing a value < 0.01 for zero time delay, revealing a single photon purity of > 99.5%. Such source arrays offer high potential for realizing on-chip integrated quantum optical circuits.

Getting the single photon to do something useful:

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Scope of Efforts:

     We utilize (lab facility) a unique suite of material / quantum nanostructure synthesis techniques (ranging from cutting-edge vapor phase to solution chemistry based) with in-situ and real-time growth monitoring and control at the atomic layer scale, structural examination [high-resolution transmission electron microscopy, ex-situ and in-situ atomic force and scanning tunneling microscopy], optical examination [high-resolution photoluminescence(HRPL), time-resolved HRPL], and electrical and opto-electronic (photocurrent) characterization. For probing the quantum optical behavior at the single photon level, we utilize custom-designed state-of-the-art instrumentation that allows establishing single photon emission statistics (sub Poissonian) and purity, determining photon indistinguishability, and two-photon interference-the basic phenomena that underlie quantum information.


    We are constantly on the look-out for "a few good students". If you have a strong undergraduate degree in science or engineering are self-driven, curious, communicative, committed to PhD, and your passion to learn greater than fear of walking unknown territory, then contact Professor Madhukar: Email, and Professor Zhang: Email. We are the place for you!

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