The Illinois‐Express Quantum Network (IEQNET), a collaboration that includes the DOE’s Fermi National Accelerator and Argonne National laboratories, Northwestern University and Caltech, has achieved the first steps toward a functional long-distance quantum network running on telecom fiber optics. Using local fiber optics, the team of researchers successfully deployed the quantum network between two U.S. Department of Energy (DOE) laboratories, 50 kilometers apart.
In this system, information is encoded through quantum entangled photons, and the challenge remains in being able to transfer this information across distances and scales without losing coherence, feature that guarantees that there has been no loss of information. Preserving information is key to any informatic system; all our digital activities require that the information transfer is securely transferred.
A way of measuring the degree of information preservation is by measuring the synchronization when both signals -the quantum (the entangled photons) and the classical (the time counter, the clock)- travel in the same fiber optic.
Image by Lee Turman, Argonne National Laboratory. To measure the synchronicity of two clocks — one at Argonne and one at Fermilab — scientists transmitted a traditional clock signal (blue) and a quantum signal (orange) simultaneously between the two labs, over the Illinois Express Quantum Network. The clocks remained synchronized within a time frame smaller than 5 picoseconds.
The main requirement is to use different wavelengths for each signal and the frequencies must be chosen as to prevent interference between them, so that they can “travel independently”, like using different lanes in a same “highway”. Finding those frequencies is the key piece of the puzzle. The results are remarkable! There was only a 5 trillionth of a second (5 picoseconds) time difference in the clocks at each location, thus ensuring the security of the information transfer.
As stated by the press release, this is the first time that quantum-encoded photons and classical signals are simultaneously delivered across a metropolitan-scale distance with an unprecedented accuracy of synchronization that allows to precisely identify and manipulate entangled photon pairs involved in quantum networks over large distances and in real-world conditions.
This will procure as well solid grounds for quantum information processing (quantum computing), offering an exponential increase in computational capacities, which now a days seem out of this world.
With this IEQNET achievement, quantum computers are closer to replace the classical information processing we currently use.
More at:
https://phys.org/news/2022-06-quantum-network-national-labs-synch.html
