The function of traditional computing is reaching its capacity. Transistor-based silicon technologies that rely on binary encoding, are failing to meet the needs of modern science. As technology advances and our scientific knowledge deepens, new and more complicated problems arise, and finding the solution to these problems allow for the development of new revolutionary applications, that would significantly impact the world. Therefore, scientists are overcoming the limitations of the traditional computer and learning how to create efficient quantum computers that could solve these problems.
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Nanophotonics, the part of nanotechnology involved in exploring how light particles at nanometer scales behave, as well as how nanometer-sized objects interact with light. The focus of nanophotonics looks into components that can transport and focus light. Quantum computing scientists are now looking to this discipline to see how it can enable the creation of scalable and efficient quantum computers.
Quantum entanglements
One method of using nanophotonics to develop quantum information processing is through utilizing quantum entanglements. This year, a research team in Austria successfully sent an entanglement of a photon and matter, over a 50km distance through an optical fiber, the longest distance that this method has achieved. This research is fundamental in advancing the technology that will be used for a future quantum internet.
The paper, that was published in Nature, demonstrates how the team entangled a photon with matter to travel a record-breaking distance. The process began with trapping a calcium atom in an ion trap and then writing a quantum state onto the calcium ions using laser beams. At the same time, the ions progressed to an excited state, emitting a photon as a result, where the quantum information is stored.
This method induced an entanglement of the atom’s quantum states, and the photon. The photon was then sent through a nonlinear crystal illuminated by a strong laser to convert its wavelength to that which is the optimum value for long-distance travel. Finally, the entangled photon was sensed through 50km of fiber optic cable. The fact that the entanglement could be sent such distances suggests that this method may allow for information to be processed using photons to the store information, opening the door to quantum computing and the quantum internet.
Silicon photonics
Another method of developing quantum information processing with the help of nanophotonics is in the use of silicon as a platform for single-photon sources, quantum bits (qubits), as well as nanoscale sensors. While still in the research phase, it is believed that silicon carbide will be instrumental in the fields of quantum computing, quantum simulation, and deep learning.
Studies have seen researchers develop arrays of nanopillars with single silicon-vacancy centers in 4H-SiC. This scalable array has demonstrated that it is readily available for communicating efficiently with free-space objective and lensed-fibers.
The vacancies in the silicon were created by irradiating the substrate with 2 MeV electron beams. Following this, the team initiated a lithographic process to form nanopillars of 800 nm height and 400–1400 nm diameter. The measured collection efficiency was high, up to 22 k counts/s optical saturation rates from a single silicon-vacancy center, while at the same time maintaining the single-photon emission as well as the optically induced electron-spin polarization properties.
The impact of the study showed that silicon carbide was proven to be a readily available platform for scalable quantum photonics- architecture that relies on qubits and single-photon sources.
Summary
Nanophotonics aims to advance the field of quantum information processing in multiple ways. Information is being sent in entangled photons and as qubits via a silicon carbide platform. In the future, we can expect to see further research improving on the methods described, leading to methods of quantum information processing that will become available to use in scientific labs, and potentially in the world’s other major information reliant industries.
Sources:
https://www.nature.com/articles/s41534-019-0186-3
https://www.degruyter.com/view/j/nanoph.2017.6.issue-3/nanoph-2016-0136/nanoph-2016-0136.xml
https://iopscience.iop.org/article/10.1070/QE2015v045n10ABEH015740
https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.6b05102
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