Los Alamos National Laboratory (LANL) released on March 25, local time. Researchers have discovered a new type of multifunctional, high-performance quantum dots for medical imaging and quantum computing.
This kind of quantum dot is different from other single-photon emitters. The new type of quantum dot can provide a stable single-spectrum tunable infrared photon stream at room temperature. This research breakthrough may lead to a series of practical applications, including quantum communication, quantum metrology, medical imaging and diagnosis.
The research results are titled "Highly versatile near-infrared emitters based on an atomically defined HgS interlayer embedded into a CdSe/CdS quantum dot" and published in the journal Nature Nanotechnology [2].
Figure｜Development of infrared emitting quantum dots (Source: LANL)
Victor Klimov, the first author of the paper, said that he successfully demonstrated high single-photon purity in infrared light, which is highly practical in the field of secure communication such as quantum key distribution.
The research team at Los Alamos National Laboratory has been able to synthesize the colloidal-nanoparticle structure very well. This structure comes from their previous work on visible light emitters, which is essentially cadmium selenide wrapped in a cadmium sulfide shell. core.
By inserting a mercury sulfide intermediate layer at the core/shell interface, the research team converted quantum dots into highly efficient infrared light emitters that can be adjusted to specific wavelengths.
Vladimir Sayevich, the chief chemist of the research project, said: “This new synthesis method allows highly precise and atomic-level control of the thickness of the mercury sulfide-emitting intermediate layer. By changing the increment of one atomic layer, it can be discretely separated. In the quantitative jump, adjust the wavelength of the emitted light and adjust the size of the cadmium selenide core in a more continuous manner."
The new quantum dots are far superior to the existing near-infrared quantum dots. These new structures can emit "flicker-free" at the single-point level. The single-photon purity at room temperature is nearly perfect and the emission rate is fast. They perform very well under both light and electrical excitation.
In quantum computing, single photons can be used as qubits. In network security applications, single photons can protect computer networks through quantum key distribution, and provide ultimate security through "unbreakable" quantum protocols.
And biological imaging is another important application. The emission wavelength of the new quantum dots is located in the near-infrared window, which is very suitable for deep tissue imaging.
People cannot see infrared, but many modern technologies rely on infrared, from night vision equipment and remote sensing to telecommunications and biomedical imaging. Even in the most emerging quantum technology, infrared light also plays an important role.
Quantum technology relies on light particles or wave-particle duality. The use of this quantum property requires "quantum light", which emits light in the form of a single quantum or photon.
Zack Robinson, a researcher in quantum dot spectroscopy of the research project, said: “In the process of manufacturing these dots, the thickness of the mercury sulfide-emitting intermediate layer of all dots in the sample is the same. This is very special, especially for a In terms of materials made by chemical methods in a beaker."
Victor Klimov, the first author of the paper, added that, however, this is only the first step. In order to make full use of "quantum light", it is necessary to realize the indistinguishability of photons, that is, it is necessary to ensure that all emitted photons are the same on the quantum mechanical level.
Reference link:
[1]https://www.lanl.gov/discover/news-release-archive/2021/March/0325-quantum-dots.php?source=newsroom-topnews-box
[2]https://www.nature.com/articles/s41565-021-00871-x
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