Long-Distance Quantum Communication
A breakthrough could allow quantum computers to be connected at 200 times greater distances.
A significant advancement in nanofabrication may allow two quantum computers to link via fiber cable across a distance of up to 2,000 kilometers (1,243 miles), rather than only a few kilometers. In the past, even relatively close systems, like those at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) and downtown Chicago’s Willis Tower, were too far apart to communicate due to the notoriously difficult connection of quantum computers over long distances.
This range is theoretically much expanded by research by Asst. Prof. Tian Zhong and his team that was published in Nature Communications. A UChicago quantum computer that was previously unable to link to the Willis Tower could be able to do so with this new method outside of Salt Lake City, Utah. “For the first time, the technology for building a global-scale quantum internet is within reach,” said Zhong, who recently won the esteemed Sturge Prize for this work.
You can also read Slovakia’s skQCI Project Accelerates EuroQCI Goals For EU
Quantum Coherence’s Role
By entangling atoms via a fiber cable, quantum computers can be connected to create strong, fast quantum networks. The quantum coherence time—the amount of time the entangled atoms retain their quantum state—is a crucial component that determines the range of this connection.
The breakthrough is the result of significantly longer quantum coherence periods for individual erbium atoms. These timings were increased by the researchers from about 0.1 milliseconds to more than 10 milliseconds. In one example, they showed coherence up to 24 milliseconds, which potentially enables quantum computers to link at an astounding 4,000 km, which is about the same distance as between Ocaña, Colombia, and UChicago PME. Purer materials that promote improved quantum entanglement and communication are used to produce this notable increase in coherence time.
You can also read LiDAR 2.0: Quantum Sensing Will Change Autonomous Vehicles
Creation Atom by Atom
Instead than employing novel materials, the invention focused on constructing rare-earth doped crystals, which are already materials, in an entirely new manner.
The Czochralski technique, which Zhong called a “melting pot,” creates these crystals. This technique involves mixing the right elements, melting them above 2,000 degrees Celsius, then gradually freezing the mixture to form a crystal. A computer component is chemically sculpted from this crystal like a sculptor cutting marble.
You can also read What is NVIDIA Quantum X800, How it Works and Components
For this reason, Zhong and his team modified the molecular-beam epitaxy (MBE) process in collaboration with materials synthesis specialist UChicago PME Asst. Prof. Shuolong Yang. MBE is a bottom-up method of nanofabrication that is closer to 3D printing. Rather of beginning with a bulk crystal and cutting it, MBE assembles the device atom by atom until the crystal is precisely shaped by spraying thin layer after thin layer.
Superior quantum coherence properties derive from the material’s exceptionally high quality or purity. This method is “highly innovative” and provides an intriguing scalable avenue for the controlled creation of numerous networkable qubits, according to Prof. Dr. Hugues de Riedmatten of the Institute of Photonic Sciences, a top leader in the field who was not involved in the study.
You can also read What is Bell Test, How it Works, Types, and Applications
The Next Phase of the Quantum Internet
Zhong and his colleagues will now investigate whether quantum computers can indeed establish long-distance connections with this enhanced coherence time.
Their first strategy is to simulate a long-distance link in Zhong’s UChicago PME lab. 1,000 km of spooled wire will be used in this test to connect two qubits that are housed in different dilution coolers. Additionally, the team is constructing a third refrigerator to create a local network, which will enable them to perform experiments locally first to mimic the look of a long-distance network in the future. According to Zhong, this effort is “all part of the grand goal of creating a true quantum internet,” which is another step in the right direction.
You can also read Quantum Teleportation 2024 2025 Breakthrough in Internet
