Quantum science has taken a significant leap forward with a groundbreaking development in the field of quantum light emitters. A team of researchers from Los Alamos National Laboratory has successfully generated a stream of circularly polarized single photons using a new approach. This breakthrough has the potential to revolutionize quantum information and communication applications. By stacking two different atomically thin materials, the researchers have achieved a chiral quantum light source without the need for an external magnetic field.
In most cases, circularly polarized light emission requires high magnetic fields, complex nanoscale structures, or spin-polarized carriers. However, the Los Alamos team has taken a different approach with their proximity-effect technique. This method offers the advantages of low-cost fabrication and improved reliability. It eliminates the need for expensive superconducting magnets or intricate photonics structures, making it a more accessible option for future applications.
One of the significant achievements of this research is the combination of two essential components in a single device. By developing a light source capable of generating a continuous stream of single photons with circular polarization, the team has effectively merged two devices into one. This integration simplifies the process and enhances the overall efficiency of quantum information and communication systems.
The researchers at the Center for Integrated Nanotechnologies utilized a single-molecule-thick layer of tungsten diselenide semiconductor stacked onto a thicker layer of nickel phosphorus trisulfide magnetic semiconductor. To further enhance the emission of circularly polarized light, nanometer-scale indentations were created using atomic force microscopy. These indentations, approximately 400 nanometers in diameter, play a crucial role in the overall functionality of the device.
The nanometer-scale indentations on the stacked materials form wells or depressions in the potential energy landscape. When a laser is focused on the stack, electrons from the tungsten diselenide monolayer fall into these depressions, stimulating the emission of single photons. This mechanism provides a controlled and continuous stream of circularly polarized photons.
In addition to stimulating the emission of single photons, the nanoindentations also disrupt the magnetic properties of the underlying nickel phosphorus trisulfide crystal. This disruption creates local magnetic moments that point outward from the materials. These local magnetic moments play a crucial role in circularly polarizing the emitted photons, making them even more valuable for quantum information and communication applications.
The research team conducted several experiments to confirm the viability and effectiveness of their approach. Through high magnetic field optical spectroscopy experiments and measurements of the minute magnetic fields of the local magnetic moments, the team successfully demonstrated their novel method of controlling the polarization state of a single photon stream.
Moving forward, the researchers are exploring ways to modulate the degree of circular polarization of the single photons using electrical or microwave stimuli. This ability to manipulate the polarization state would provide a means of encoding quantum information into the photon stream. Additionally, the team plans to further develop the technology by coupling the photon stream into waveguides to create photonic circuits for an ultra-secure quantum internet.
The successful generation of circularly polarized single photons without the need for an external magnetic field represents a significant breakthrough in the field of quantum light emitters. The low-cost fabrication, reliability, and integration of two essential components in a single device make this approach highly promising for future quantum information and communication systems. With further advancements, the potential for a secure and efficient quantum internet becomes more tangible. The future of quantum technology is brighter than ever, thanks to the ingenuity and dedication of researchers at Los Alamos National Laboratory.
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