From left: Professor Sun Namkoong and Professor Je-Hyung Kim of the Department of Physics at UNIST, and researchers Satyabrata Behera and Jong-Seong Moon. Courtesy of UNIST.
Most quantum science and expertise begins with controlling a single photon (a particle of light) in a quantum state. A analysis group in South Korea has efficiently overcome a persistent downside the place the standard of a single-quantum light source degrades when turned on or off with {an electrical} swap. They achieved a single-photon purity of 94%, a key efficiency indicator.
Ulsan National Institute of Science and Technology (UNIST) introduced on the twenty third {that a} group led by Professors Sun Namkoong and Je-Hyung Kim from the Department of Physics has developed a high-purity single-quantum light source based mostly on a 2D semiconductor that suppresses the ‘Stark effect’. The analysis findings had been revealed within the worldwide journal ‘Nano Letters’ on the eleventh (native time).
A single-quantum light source is a tool that emits a single photon inside a short second, on the dimensions of nanoseconds (ns, one-billionth of a second). In distinction, standard light sources like fluorescent lamps emit numerous photons per second. Next-generation quantum applied sciences, reminiscent of quantum computing and quantum cryptography, hinge on controlling the quantum state of single photons.
For the sensible software of single-quantum light sources, quantum light switching expertise, which may independently flip particular person sources on and off with electrical indicators, is taken into account important.
The Stark effect is a phenomenon the place the vitality of an emitted photon adjustments when a voltage is utilized to show the light source on or off. If the photon’s vitality adjustments, it’s handled as an unintended photon, stopping the specified quantum phenomenon from occurring accurately. The problem posed by the Stark effect will increase as extra light sources are built-in.
A schematic of the single-quantum light source developed by the analysis group. A single photon is emitted from the tip of the pyramid-shaped construction. Courtesy of UNIST.
The analysis group suppressed the Stark effect by making a microscopic air hole inside the light source. The construction consists of a skinny aluminum oxide insulating layer coated on a pointy, pyramid-shaped silicon construction, with a 2D semiconductor, tungsten diselenide (WSe2), positioned on prime.
The precept is that the microscopic air hole shaped between the sharp tip of the silicon and the semiconductor reduces the electrical area transmitted to the semiconductor to about one-twentieth of its unique energy, thereby suppressing adjustments within the photon’s vitality.
In a single-quantum light source, the potential of a number of photons being emitted concurrently exists, which degrades efficiency. A tool is taken into account a single-quantum light source if this chance is under 0.5, and the nearer to 0, the upper the single-photon purity.
When the group added a hexagonal boron nitride (h-BN) movie to the developed construction, background luminescence from surrounding defects was considerably diminished, lowering the multi-photon emission chance from 0.37 to 0.06. This signifies that single photons are generated with 94% purity.
The group acknowledged, “We have proposed a structure that stably maintains the photon’s energy and improves purity while controlling single photons with electrical signals.” They added, “Because it is compatible with silicon semiconductor processes, it can be directly utilized in the future development of chip-based quantum communication, photonic quantum computing, and quantum optical sensors.”
– doi.org/10.1021/acs.nanolett.5c05425
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