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Research Spending & Results

Award Detail

Doing Business As Name:Vanderbilt University
  • Richard F Haglund
  • (615) 322-2828
  • Joshua D Caldwell
Award Date:07/26/2021
Estimated Total Award Amount: $ 550,000
Funds Obligated to Date: $ 550,000
  • FY 2021=$550,000
Start Date:08/15/2021
End Date:07/31/2024
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.049
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Characterizing and controlling optical and vibrational dynamics of single-photon emitting defects in hexagonal boron nitride
Federal Award ID Number:2128240
DUNS ID:965717143
Parent DUNS ID:004413456
Program Officer:
  • Paul Lane
  • (703) 292-2453

Awardee Location

Street:Sponsored Programs Administratio
Awardee Cong. District:05

Primary Place of Performance

Organization Name:Vanderbilt University
Street:Sponsored Programs Administratio
Cong. District:05

Abstract at Time of Award

Nontechnical Description. Ultrasensitive quantum sensors and unbreakable quantum cryptography technologies use single photons (particles of light) or pairs of photons to detect, encode, transmit and retrieve quantum information. Hence materials in which single photons can be generated and manipulated on demand are essential to deploying user-friendly quantum technologies. This project focuses on finding, characterizing and manipulating single-photon emitters in hexagonal boron nitride (hBN). Ensembles of single-photon emitters are known to exist in hBN, and they are extremely bright and stable at room temperature. Crystal vibrations will be manipulated in this project to improve the color purity of the single-photon emitters. This take advantage of the fact that crystal vibrations of hBN couple to the photon emitters at room temperature just as light and sound are coupled through the photoacoustic effect discovered by Alexander Graham Bell. Success in this project will have a transformative impact on quantum-device technologies because hBN emitters can be packaged in an on-chip format that is compatible with microelectronics and fiber-optic communications. The project will train students in quantum information sciences through a multi-disciplinary approach that connects optics, materials and computational science. Established outreach programs at Vanderbilt’s Center for Science Outreach and Center for Teaching will prepare the project team to visit middle- and high-school classes in Nashville city schools and underserved neighboring counties, to inspire and encourage future study and work in quantum science and technology. A diverse, inclusive research team will be built in partnership with the decades-old Bridge-to-Ph.D. program connecting students from Historically Black Fisk University to Vanderbilt research groups. Technical Description. Scalable quantum technologies based on light require well-characterized, controllable solid-state, single-photon emitters that can be manipulated and entangled on demand. Ensembles of crystal defects in hexagonal boron nitride (hBN) host single-photon emitters with a constellation of useful properties: ultra-high brightness, narrow linewidth, and photostability at room temperature, and hyperbolic phonon polaritons with an exceptionally large photon density of states in the mid-infrared are also supported in hBN. However, the large spectral mismatch between quantum-emitter frequencies (visible vs near-infrared) and hyperbolic-polariton and phonon frequencies (mid-infrared) makes it difficult to exploit all of these desirable properties simultaneously. This project will capitalize on the high phonon density of states in hBN to control single-photon emission and increase spectral purity by anti-Stokes pumping of phonon sidebands. Spectrally and temporally resolved near-field spectroscopy and microscopy will be deployed to identify and characterize individual single-photon emitters in mono- and few-layer hBN flakes by photoluminescence, nano Fourier-transform infrared spectrometry and photon-correlation studies; determine electronic properties of emitting states and the vibrational interactions that couple to them using nano-optical scanning probe microscopy in the mid-infrared; demonstrate active control of emitter lifetime and frequency by locally varying the dielectric environment of the emitter by pumping anti-Stokes photon modes; and explore the effects of phonon-emitter coupling and local strain on spectral purity and photon entanglement between two emitters on the same hBN flake. By characterizing individual single-quantum emitters in hBN and demonstrating controlled entanglement, the project opens a transformative path to planar, room-temperature devices for quantum cryptography, computation and sensing in a form factor intrinsically adaptable to on-chip geometries and optical-fiber coupling. These experiments will resolve long-standing uncertainties about the physical properties of the defect-based single-photon emitters in hBN, enabling a deeper understanding of the physical mechanisms underlying emission and entanglement. Controlling photon purity through the anti-Stokes mechanism and controlled strain gradients in single flakes of hBN may also enhance the stability of photon entanglement by separating the strain mechanism and electron-phonon coupling from the electronic process of single-quantum emission. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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