A quantum light source could lead to a quantum internet

Molybdenum ditelluride material (blue and yellow lattice) couples telecom wavelength quantum emitters only atoms thick into optical fibers with minimal loss. The devices generate single photons (red) when triggered by optical signals (green). Credit: Huan Zhao, Center for Integrated Nanotechnology, Los Alamos National Laboratory

The ability to integrate fiber-based quantum information technology into existing optical networks would be an important step toward applications in quantum communications. To achieve this, quantum light sources must be able to emit single photons in the 1.35- and 1.55-micrometer ranges where light travels with minimal loss in existing optical fiber networks, such as telecommunications networks, with controllable positioning and polarization. This combination of features has been elusive until now, despite two decades of research efforts.

Recently, two-dimensional (2D) semiconductors have emerged as a new platform for next-generation photonics and electronics applications. Although scientists have demonstrated 2D quantum emitters operating in the visible regime, single-photon emission in the most desired telecommunication bands has never been achieved in 2D systems.

To solve this problem, Los Alamos National Laboratory researchers developed a voltage engineering protocol to deterministically create two-dimensional quantum light emitters with wavelengths operating in the O and C telecommunication bands. The emission polarization can be tuned by the magnetic field using the degree of freedom in the valley.

The researchers achieved 90 percent single-photon purity and an operating temperature of 77 Kelvin. These fundamental results open the door to exciting developments in quantum technologies.

The study was published in the journal Nature Connections.

Conventional light sources for fiber-optic telecommunications emit many photons simultaneously. Photons are particles of light that travel in waves. In modern telecommunication networks, information is transmitted by modulating the characteristics of light waves traveling in optical fibers, similar to the modulation of radio waves in AM and FM channels.

In quantum communication, however, information is encoded in the phase of a single photon—its position in the wave along which the photon travels. This makes it possible to connect quantum sensors and connect quantum computers in a network that spans large distances.

Researchers have recently produced single-photon sources with wavelengths compatible with existing fiber communications networks. They did this by placing layers of molybdenum ditelluride semiconductors just atoms thick on top of a series of nano-sized pillars. Researchers demonstrate for the first time this type of tunable light source suitable for use in telecommunications systems.

The results of this research allow for the first time to integrate quantum light sources made of two-dimensional materials into existing communication networks. In addition, the two-dimensional nature of the material facilitates layer-by-layer construction of devices. This could help integrate these light sources into emerging quantum computers to build larger, modular computing systems and achieve quantum dominance for practical applications.

Site-controlled telecom-wavelength single-photon emitters in atomically thin MoTe, Huan Zhao et al2, Nature Connections (2021). DOI: 10.1038/s41467-021-27033-w

Provided by the US Department of Energy

Quote: Quantum light source could pave way to quantum internet (2022, December 5) Accessed on December 5, 2022 https://phys.org/news/2022-12-quantum-source-pave-internet.html

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