Los Alamos National Laboratory
Nanotechnology and Advanced Spectroscopy Team

Funding: Los Alamos National Laboratory Directed Research and Development (LDRD) Program Office, directed resarch (DR) project.


Quantum photonics explores and exploits quantum states of light in the context of quantum computing, communication, imaging, and metrology, the sub-fields of quantum information science (QIS). A key element of any quantum photonic circuit is a ‘single-photon emitter’ (SPE). An ideal SPE delivers exactly one photon at a designated time – no more, no less – and, importantly, all emitted photons are ‘indistinguishable’, that is, quantum-mechanically identical in wavelength, phase, polarization, and direction. Zero-dimensional (0D) Semiconductor 'quantum dots' (QDs) fabricated via epitaxial approaches have emerged as a highly promising SPE platform. While demonstrating the tremendous potential of 0D-structures in QIS, epitaxial QDs have several shortcomings including a fairly narrow operational spectral range (~800−1100 nm), dot-to-dot variations in the emission energy due to size polydispersity, difficulty for on-chip integration, and the need for cryogenic liquid-helium (He) cooling.


Here we propose that by using a colloidal form of QDs − chemically synthesized nanocrystals (NCs) − we can address the limitations of epitaxial-QD SPEs while retaining the advantages of 0D-systems. In particular, strongly confined NCs can easily access the small-size regime where the spacing between their discrete atomic-like electronic states greatly exceeds typical thermal energies, which mitigates the effects of thermal noise. In addition, they feature ‘quantized’ vibrational modes characterized by large energies, which simplifies isolation of optically coherent exciton emission. Further, by manipulating confined electronic and phonon states, it is possible to extend exciton coherence.

The goal of this project is to exploit the unmatched flexibility of colloidal NCs for demonstrating atomic-like emitters with long-lived optical coherence that is preserved at elevated temperatures. In addition, we aim to exploit a size-controlled NC band gap for realizing high-fidelity sources of quantum light with an arbitrary wavelength tunable across both visible and near-infrared (NIR) ranges. A further objective is to implement integrated NC-photonic circuits, through which we will be able to excite a selected NC (or an NC group) and then read out desired information on demand. This will demonstrate the ‘integrability’ and scalability of the NC-SPE approach and, in addition, will provide a powerful capability for systematic studies of the effects of controlled photonic environment on SPE-related NC properties.

Thrust 1 (PHYS) elucidates the fundamental physics of NC SPE's with a focus on approaches for achieving high single-photon purity and the realization of long-lived optical coherence maintained at elevated temperatures.

Thrust co-leader

Sergei Tretiak, T-1

Thrust co-leader

Scott Crooker, NHMFL

Young-Shin Park, C-PCS

Mateusz Goryca, NHMFL

Zack Robinson, UMN / C-PCS

Thrust 2 (PHOT) explores controlled photonic environments for boosting excitonic coherence via incorporation of NC SPE's into high-quality-factor optical cavities, and additionally the integration of NC SPE's into large-scale on-chip photonic circuits.

Thrust leader

Victor Klimov, C-PCS

Mark Croce, NEN-1

Kivanc Gungor, C-PCS

Heeyoung Jung, C-PCS

Thrust 3 (CHEM) exploits knoweledge gained in thrust 1 to practically realize color-selected visable and infrared SPE's with high single-photon purity and indistinguishability.

Thrust leader

Sergei Ivanov, CINT

Igor Fedin, C-PCS

Vladimir Sayevich, C-PCS

Tom Nakotte, NMSU / C-PCS


  • Oct 17, 2019: Inaugural all-hands meeting
  • Oct 11, 2019: Klimov visit to Sandia Labs to discuss collaboration in integrating NC SPE's into photonic circuits
  • Oct 14, 2019: CHEM meeting
  • Oct 21, 2019: PHYS meeting
  • Oct 24, 2019: Group teleconference with Paul Davids @ Sandia on incorporation of NCs into their photonic circuits
  • Nov 4, 2019: Guest Speaker 1, Hou-Tong Chen from CINT on recent developments of metasurfaces for quantum materials
  • Nov 18, 2019: All-hands meeting
  • Nov 21, 2019: Croce visit to Sandia Labs for tour and to discuss using their existing photonic circuits for NC SPE on-chip integration
  • Nov 26, 2019: Management Review meeting

Relevant Publications

  1. Dual-Emitting Dot-in-Bulk CdSe/CdS Nanocrystals with Highly Emissive Core- and Shell-Based Trions Sharing the Same Resident Electron. Pinchetti, V., Shornikova, E. V., Qiang, G., Bae, W. K., Meinardi, F., Crooker, S. A., Yakovlev, D. R., Bayer, M., Klimov, V. I. Nano Letters, Accepted (2019)
  2. Asymmetrically strained quantum dots with non-fluctuating single-dot emission spectra and subthermal room-temperature linewidths. Park, Y., Lim, J. and Klimov, V. I. Nature Materials 18, 249–255 (2019)
  3. Thick-Shell CuInS2/ZnS Quantum Dots with Suppressed “Blinking” and Narrow Single-Particle Emission Line Widths. Zang, H., Li, H.,Makarov, N. S., Velizhanin, K. A., Wu, K., Park, Y-S, Klimov, V. I. Nano Letters 17, 3, 1787-1795 (2017)
  4. Room Temperature Single-Photon Emission from Individual Perovskite Quantum Dots. Park, Y-S, Guo, S., Makarov, N. S., Klimov, V. I. ACS Nano 9, 10, 10386-10393 (2015)
  5. Spectral and Dynamical Properties of Single Excitons, Biexcitons, and Trions in Cesium–Lead-Halide Perovskite Quantum Dots. N. S. Makarov, S. Guo, O. Isaienko, W. Liu, I. Robel, V. I. Klimov, Nano Letters 16, 2349-2362 (2016)
  6. Effect of the Core/Shell Interface on Auger Recombination Evaluated by Single-Quantum-Dot Spectroscopy. Park, Y.S., Bae, W. K., Padilha, L. A., Pietryga, J. M., Klimov, V.I., Nano Letters 14, 396-402 (2014)
  7. Super-Poissonian Statistics of Photon Emission from Single Core/Shell Nanocrystals Coupled to Metal Nanostructures. Park, Y. S., Ghosh, Y., Chen, Y., Piryatinski, A., Xu, P., Mack, N. H., Wang, H. L., Klimov, V. I., Hollingsworth, J. A., Htoon, H. Physical Review Letters, 110, 117401 (2013)
  8. Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots. Galland, C., Ghosh, Y., Steinbrück, A., Sykora, M., Hollingsworth, J. A., Klimov, V. I., Htoon, H. Nature 479, 203–207 (2011)
  9. Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields. Schaller, R. D., Crooker, S. A., Bussian, D. A., Pietryga, J. M., Joo, J., Klimov, V. I. Physical Review Letters 105, 067403 (2010)
  10. Type-II Core/Shell CdS/ZnSe Nanocrystals:  Synthesis, Electronic Structures, and Spectroscopic Properties. Ivanov, S. A., Piryatinksi, A., Nanda, J., Tretiak, S., Zavadil, K. R., Wallace, W. O., Werder, D., Klimov, V. I. Journal of the American Chemical Society 129, 38, 11708-11719 (2007)
  11. Multiple temperature regimes of radiative decay in CdSe nanocrystal quantum dots: Intrinsic limits to the dark-exciton lifetime. Crooker, S. A., Barrick, T., Hollingsworth, J. A., Klimov, V. I. Applied Physics Letters 82, 2793 (2003)

November 2019

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