The study “Loophole-free Bell test with Superconducting Circuits” in Nature
Barcelona, 10th May 2023.
Random number generators, developed by Quside Technologies in collaboration with ICREA Professor at ICFO Morgan W. Mitchell, made possible a ground-breaking experiment to be published 10 May 2023 in Nature. The experiment, in the laboratories of Andreas Wallraff at ETH Zurich, performed a “loophole-free Bell test,” similar to experiments that won the Nobel Prize in Physics last year. For the first time, the ETHZ experiment was able to perform this kind of experiment with superconducting quantum bits, the basis for today’s most advanced quantum computers. The results show “spooky action at a distance,” in which objects in different places behave as if they were a single system.
As described by the group at ETHZ, the ETHZ experiment first “entangled” two superconducting qubits at temperatures near absolute zero and separated by 30 meters of distance. They then measured the state of the qubits simultaneously, and observed that the state of one qubit usually agreed with the state of the other qubit, a coordinated response consistent with “spooky action at a distance.” To be sure this coordination was not due to ordinary signals traveling from one qubit to the other, the ETHZ team chose randomly which type of measurements to make on the qubits, and they made the measurements so quickly that not even a signal at the speed of light could reach the other qubit in time.
This feat required extremely fast random number generators, and for this the ETHZ team turned to Quside and Prof. Mitchell’s research group at ICFO to develop a random number generator with unprecedented speed. Quside adapted their patented quantum random number generation technology, combining a novel parallel architecture with an extremely fast “randomness extraction” stage. In this way, the QRNG devices delivered pure random bits in 17 nanoseconds, the time it takes light to travel 5 meters.