image: The ground station's telescope view more
Credit: Tel Aviv University
The Center for Quantum Science and Technology at Tel Aviv University has built the first ground station in Israel – and among the most advanced in the world – for tracking, sensing, hyperspectral imaging, and optical and quantum communication with satellites in orbit around the Earth. The station includes a satellite observatory dome with a diameter of 4.25 meters, a tracking system, a primary high-speed camera and secondary tracking cameras, laser equipment, single-photon detectors, and a tracking robot that can carry two telescopes simultaneously. At this stage, the robot arm holds a 24-inch telescope, and in the next stage, the observatory will be equipped with another telescope designed for photography in the infrared range, as well as thermal and hyperspectral cameras.
Video about the ground station:
“The ground station is designed for observing satellites, which are small bodies 400-500 kilometers high that move at about 30,000 kilometers an hour,” says Prof. Yaron Oz, head of the Center for Quantum Science and Technology at Tel Aviv University. “The ability to track satellites is a very precise skill. The satellite passes by very quickly, and during this time you have to photograph it in the center of the image and in several different ranges of the electromagnetic spectrum in order to learn details about it. This is the first and only satellite observatory in Israel, and it is among the most advanced in the entire world.”
In addition to regular optical communication, which uses lasers or LEDs of different wavelengths, the new ground station will also enable the conduction of experiments in quantum optical communication. Advanced communications use the quantum properties of individual photons to transmit encrypted information.
“Theoretically speaking, quantum communication is completely encrypted,” explains Prof. Oz. “It is impossible to launch a cyber attack and copy the information, because in quantum mechanics there is a principle that prevents copying. As soon as a third party tries to intercept a message, they destroy the original signal – for example, by changing the polarization of the photons – and both communicating parties will know that someone tried to listen in on them. That's how it works in theory. In practice, there are quite a few research questions that need to be answered. For example, what do we do with interference in a signal that is not created as a result of attempted eavesdropping, but rather, for example, from the weather? Should we use qubits or qudits, photons that have more than two states? And more generally, how much information can be transmitted this way within the limited transmission time in which the satellite passes over the ground station? The list of unanswered questions is long. It must be understood that quantum communication is a completely experimental field. There are protocols from experiments conducted in laboratories, but the only country that has successfully demonstrated such communication is China, which did so already in 2016. The Americans also apparently succeeded in this, but they published nothing about it in scientific journals. Apart from these two superpowers, a few countries like Germany, Singapore, and now Israel are preparing to demonstrate this capability.”
In the first phase of the project, the Tel Aviv University researchers will try to establish optical communication followed by quantum communication between ground stations, between ground stations and drones, and then between ground stations and a satellite of one of their international partners. Within two to three years, the researchers hope to raise the funds to build a dedicated “blue and white” quantum satellite.
“We are employing the ‘tower and stockade’ method,” says Prof. Oz. “In the beginning, we will place a transmitter on the roof of the second building of the School of Physics, in an attempt to produce an immune quantum key with a rate of hundreds to thousands of bits per second, with the aim of learning and improving the positioning, switching and synchronization capabilities of the light sources and the single-photon detectors. Later, we would like to reduce the size of the transmission system and integrate it into an airborne system, initially with drones, and establish a network of quantum communications. Ultimately, we would also like to launch our own satellite, which will try to establish quantum communication with the ground station and with a similar satellite in Singapore.”
Prof. Ady Arie of the Fleischman Faculty of Engineering, Prof. Haim Suchowski and Prof. Erez Etzion of the Raymond and Beverly Sackler School of Physics, director of the optical ground station Michael Tzukran, and research students Dr. Georgi Gary Rozenman, Yuval Reches and Tomer Nahum are also participating in the groundbreaking project. The project is being funded by the university’s Center for Quantum Science and Technology, led by Prof. Yaron Oz and under the administrative management of Ms. Ronit Ackerman, and by the Israel Space Agency under the Ministry of Innovation, Science and Technology.