Researchers at Los Alamos National Laboratory have created a new class of quantum dots with potentially great potential for medical imaging, quantum cryptography and quantum computing.
A new source of single photons for quantum cryptography, qubits, and more. The uniqueness of the development lies in the fact that spectrally pure single photons are emitted at room temperature in a widely tuned wavelength range. Unlike other emitters, processes are possible under normal environmental conditions, which expands their application.
It is the demonstration of the high purity of single-photon in the infrared range that has direct application in areas such as quantum key distribution for secure communication, explains Viktor Klimov. He is the lead author of a paper published in the journal Nature Nanotechnology.
To create quantum dots (pillars) that emit single photons, scientists used synthesis in a solution of colloidal nanoparticles. The quantum dots obtained in the course of chemical processes are a cadmium selenide core in a cadmium sulfide shell. To convert such structures into single-photon emitters, the researchers inserted a layer of mercury sulfide between the shell and the core. It turned out that a simple increase in the thickness of the interlayer discretely changes the wavelength of the photon radiation.
The new structures are far superior to existing near-infrared quantum dots, these new structures exhibit “unblinking” high-speed radiation at the level of one dot, almost perfect single-photon purity at room temperature (which gives “quantum light”). They are stable under both optical and electrical excitation.
“This is only the first step. To make full use of “quantum light”, it is necessary to achieve indistinguishability of photons. That is, to make sure that all the emitted photons are quantum-mechanically identical. This is an extremely difficult task, which we will tackle further in our project,” concludes Viktor Klimov.