Single photon source integrated in optical circuit

A Dutch research team has found a single photon source that can be fully integrated in optical circuits for optical quantum computation. This discovery paved the way for the emergence of single-photon quantum computing. Related papers were published in the latest edition of Nano Express.

So far, many research teams have been able to perform optical quantum calculations on a small scale with several photons. The feasibility of “linear optical quantum computation” has been fully demonstrated, but single photon quantum computation is still rarely involved.

According to the researchers, the greatest challenge in building an efficient single-photon quantum computing system is to integrate multiple previously incompatible components onto a single platform. These components include a single photon source (eg, quantum dots), routing equipment (eg, waveguides), and chambers for manipulating photons, filters, as well as quantum gate devices and single photon detectors. In the new study, the researchers creatively embedded a single photon capable of generating quantum dots into a nanowire and encapsulated it in a waveguide. To achieve this, extremely high precision is required, and they use a component called "nano-manipulator." Once inside the waveguide, researchers can manipulate single photons into specific optical circuits.

Iman Esmerzade of Delft University of Technology in the Netherlands, who is in charge of this research, said: “We have proposed and implemented integrated quantum optics that can take into account the advantages of high-quality single-photon sources and silicon-based optics. It is a hybrid solution.In addition, unlike similar studies, the technology is completely defined, that is, the quantum source with the selected properties is integral with the quantum circuit.The new method is expected to become the future scalable integrated quantum optical circuit. In addition, the platform provides physicists with a new tool for studying the interaction between light and matter at the nanoscale and quantum electrodynamics."

The most important performance indicator in linear optical quantum computation is the coupling efficiency between single photon source and photonic channel. Inefficiency represents the loss of photons, which reduces the reliability of the computer. At present, the experimental device has been able to achieve a coupling efficiency of 24%, and after optimizing the waveguide design and related materials, this data is expected to increase to 92%.

In addition to improving coupling efficiency, researchers also plan to implement entanglement on the chip to increase the complexity of photonic circuits and single-photon detectors, eventually integrating quantum networks on the chip. (Reporter Wang Xiaolong)