The potential of quantum computing could be amplified by a quantum internet, and at the heart of this innovation are photons—tiny particles of light. These photons, which interact minimally with their surroundings, are ideal for transporting quantum information across vast distances while preserving delicate entanglement states. However, the challenge lies in generating photons at telecom wavelengths, essential for efficient long-distance transmission through fiber-optic cables.

Figure 1. A Quantum Defect Emitting a Single Photon. (Credit: Mark Turianksy)

Figure 1 is an illustration depicting a quantum defect emitting a single photon. Decades of advancements have led to highly efficient fiber-optic cables that transmit photons with minimal loss. Yet, this efficiency is limited to a narrow wavelength range known as the “telecom wavelength band.” Finding quantum defects that emit photons at these wavelengths has been challenging. Fortunately, funding from the U.S. Department of Energy and the National Science Foundation (NSF) has enabled researchers at the UC Santa Barbara College of Engineering to make significant progress in this area. Their research, detailed in the journal APL Photonics, focuses on the “Rational Design of Efficient Defect-Based Quantum Emitters.” [3]

According to UCSB materials professor Chris Van de Walle, “Atoms are constantly vibrating, and those vibrations can drain energy from a light emitter. As a result, rather than emitting a photon, a defect might instead cause the atoms to vibrate, reducing the light-emission efficiency.” [2] Van de Walle’s team developed theoretical models to understand how atomic vibrations impact photon emission and investigated how various defect properties affect efficiency.

Their findings reveal why single-photon emission efficiency drops significantly as the emission wavelength moves from visible light into the telecom band’s infrared range. The model also identifies strategies to enhance the brightness and efficiency of quantum emitters. [1] Mark Turiansky, a postdoctoral researcher in Van de Walle's lab, notes, “Choosing the host material carefully, and conducting atomic-level engineering of the vibrational properties are two promising ways to overcome low efficiency.”

Additionally, coupling to a photonic cavity—a technique supported by computer engineering professor Galan Moody and graduate student Kamyar Parto—has shown promise in addressing this challenge. The team is optimistic that their model and the insights it provides will aid in developing innovative quantum emitters crucial for the quantum networks of tomorrow.

Source: University of California - Santa Barbara

References:

1. https://www.nanowerk.com/nanotechnology-news3/newsid=65593.php
2. https://bioengineer.org/bright-prospects-for-engineering-quantum-light/
3. https://www.eurekalert.org/news-releases/1053133

Cite this article:

Hana M (2024), How UCSB Researchers Are Paving the Way for the Quantum Internet, AnaTechMaz, pp. 150