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CNST and ITL Researchers Change the Color of Single Photons from a Quantum Dot
Converting single photon emission from one wavelength to another is an important resource for integrating future quantum systems that combine low-loss optical transmission in the near-infrared with long-lived memories in the near-visible. It is also important in addressing the significant detection challenges present in currently available near-infrared single photon counters.
Addressing this problem, a collaborative research effort from CNST and ITL has demonstrated frequency upconversion of single photons from a semiconductor quantum dot from the near-infrared to the near-visible.
As described in an upcoming issue of Nature Photonics, the researchers achieved this "quantum transduction" using an on-demand 1300 nm single photon source developed in CNST and an upconversion single photon detector developed in ITL.
The single photons were generated using pulsed-excitation of an InAs/GaAs quantum dot at a temperature of 8K, and they were efficiently extracted from the low temperature environment using a novel optical fiber interface. By using a pump at 1550 nm, the single photons at 1300 nm band were converted to 710 nm in a nonlinear optical sum-frequency device, and then detected by a silicon based avalanche photodiode (See details in NIST Monthly Highlights, May 2009). The higher sensitivity of silicon avalanche photodiodes at near-visible wavelengths improved the dynamic range of the measurements by 25 times compared to InGaAs detectors, allowing the researchers to confirm that the 710 nm light was still quantum mechanical in nature and still predominantly composed of single photons.
The results open up possibilities for building so-called "hybrid quantum systems", where light from bright single photon sources, such as quantum dots, can be transmitted through optical fibers with very low loss in the 1300 nm wavelength region and then interfaced with quantum memories commonly operated in the near-visible. The work may also improve near-infrared detector technology, where low-light level measurements are difficult due to performance limitations in standard commercially available InGaAs avalanche photodiode devices.
Matthew T. Rakher,
CONTACT: Kartik Srinivasan (CNST), ext. 5938, Xiao Tang (ITL), ext. 2503