New class of versatile, high-performance quantum dots primed

A new class of quantum dots provides a steady stream of single, spectrally tuned infrared photons under ambient conditions and at room temperature, unlike other single photon emitters. This breakthrough opens up a range of practical applications, including quantum communication, quantum metrology, medical imaging and diagnostics, and clandestine labeling.

"The performance of high single-photon purity in infrared has immediate utility in areas such as quantum key distribution for secure communication," said lead author Viktor Klimov of a paper published today in Nature Nanotechnology by scientists at Los Alamos National Laboratory.

The Los Almos team has developed an elegant approach to synthesize colloidal-nanoparticle structures derived from their prior work on visible light emitters based on a core of cadmium selenide enclosed in a cadmium sulfide shell. By placing a mercury sulfide interlayer at the core / shell interface, the team transformed quantum dots into highly efficient emitters of infrared light, which can be tuned to a specific wavelength.

"This new synthesis allows for highly precise, atomic-level control of the thickness of the emitted mercury sulfide interlayer. By changing it in increments of a single atomic layer, we can tune the wavelength of the emitted light by jumping to discrete amounts of discrete amounts. , And so forth. Adjust this in a more sustained fashion by tuning the cadmium selenide core size, "said Vladimir Siavich, the lead chemist of the project.

Better than existing near-infrared quantum dots, these new structures show "blinking-free" emission at the single-dot level, which is almost absolute single-photon purity (which produces "quantum light") at room temperature, and faster. Rate of emission from. They both behave very well with optical and electrical excitation.

Single photons can be used as quibes in quantum computing. In cyber security applications, single photons can protect computer networks through quantum key distribution, which provides ultimate security through "unbreakable" quantum protocols.

Bio-imaging is another important application. The emission wavelengths of the newly developed quantum dots are within the near-infrared bio-transparency window, which makes them well suited for deep tissue imaging.

People cannot see infrared light, but many modern technologies rely on it, from night vision devices and remote sensing to telecommunications and biomedical imaging. Infrared light is also a big player in emerging quantum techniques that rely on the duality of light particles, or photons, which can also behave as waves. To uncover this quantum property, sources of "quantum light" are required that emit light in the form of individual quanta, or photons.
"There is also a cool chemical element in achieving single-atomic layer accuracy in making these dots," said Jack Robinson, a member of the project focusing on quantum dot spectroscopy. "The thickness of the emitted mercury sulfide interlayer is similar for all points in the sample. It is very unique, especially for a chemically formed material in a beaker."

Klimov said, "However, this is just the first step. To take full advantage of 'quantum light' one needs to achieve photon indivisibility, that is, to ensure that all emitted photons are quantum-mechanically the same. This is the one Extremely difficult work, which we will take forward in our project. "

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