The noon state is a critical quantum state where n particles are “at the same time” and in another state at the same time. Here, the particles are trapped in two wells within a trap formed by the laser. Thus, the overlapped state consists of all particles in the well on the left and in which they are trapped on the right. The particles interact with each other and stick together when they are at the same site, preventing isolated particles from leaving the trap. Credit: University of Liege/S. Dengis
Until now, creating quantum overlaps of ultracold atoms has been a real headache, and it has been too late to be realistic in the lab. Researchers at the University of Liège have now developed a new innovative approach that combines geometry with “quantum control.” This significantly accelerates processes and paves the way for practical applications of quantum technology.
This paper is published in Journal Physical Review A.
Imagine being in a supermarket filled with carts. Challenge: Access checkout before others without dropping the product into the corner. Solution? Choose a route with as few corners as possible to speed up without slowing down. That’s exactly what Simon Dengis, a doctoral student at Liege University, managed to do, but in the world of quantum physics.
Together with colleagues in the PQS (Quantum Statistical Physics) group, Dengis developed a protocol for quickly generating what is called the noon state.
“These states, which look like miniature versions of Schrödinger’s famous cats, are quantum superpositions,” explains the physicist. “These are of great concern for technologies such as ultra-fast quantum sensors and quantum computers.”
Time failure
The main challenge? Manufacturing in these states usually takes too long. We’ve spoken for more than a few minutes, which often exceeds the lifespan of the experiment. Cause? The energy bottleneck, the “sharp bend” of the evolution of the system, forcing it to slow down.
This is where the Uliège team opens new ground. By combining two powerful concepts, we have succeeded in “smoothing the road” of atoms by combining correspondent driving with optimal geodetic pathways. Result: The system can evolve faster, like a driver that predicts bends by tilting the tray, without losing the trajectory of the desired state.
“This strategy saves a considerable amount of time. In some cases, the process accelerates by 10,000 times, while maintaining a 99% fidelity. If it previously took about 10 minutes to create such a state, the researchers managed to significantly reduce this latency to 0.1 seconds.
Anti-diabatic controls correct system inertia by modifying the system in a specific way. In this case, to compensate for the water movement caused by the waiter’s movement, the latter can tilt the tray to correct the inertia of the glass, preventing it from falling over. Credit: University of Liège/S. Dengis
Toward practical applications
This breakthrough will ultimately allow you to produce a midday state with supercooled atoms. This opens up the prospects for quantum measurements (ultra-sensitive measurements of time, rotation, or gravity) and quantum information technology. Ultimately, these tools can improve instruments such as quantum gyroscopes and miniature gravity detectors.
This study shows how theory and experiment come together to bring about concrete advancements in quantum physics. By combining mathematical concepts, basic physics and experimental feasibility, Uliège researchers have made a breakthrough that allows them to successfully transform ideas that were once theoretical to tomorrow’s technology.
The proposed protocol (Blue, GCD) allows for the expansion of the energy bottleneck (compared to the red regular protocol). Images can be understood in the context of bike racing. Red bikes are not “smooth” for turns, so they need to brake much more than blue bikes. Therefore, the Blue Bike arrives at its destination before the opponent. Here, the change in the energy (and therefore its state) of the system is too sudden, allowing the process to accelerate dramatically. Credit: University of Liège/S. Dengis
Quantum superposition and noon state
Quantum superposition is the idea that quantum systems (atoms, electrons, photons, etc.) can exist simultaneously in several states, unless observed. The most frequently used example to illustrate this concept is the Schrödinger cat. The cat is trapped in a box. According to Quantum Mechanics, the cat is alive and dead until the box is opened.
The simultaneous combination of these two states is called superposition. It is only by opening the box that we force nature to choose a state: alive or dead. The noon state is an example of quantum superposition. All atoms are in both the left and right wells. It can be found at either time only at the moment of measurement.
Details: Simon Dengis et al accelerated the creation of noon states using ultra-cold atoms via counter-driving, physical review A (2025). doi: 10.1103/physreva.111.l031301. on arxiv: doi: 10.48550/arxiv.2406.17545
Provided by De Liege University
Quote: Quantum Ultra Highway for Ultrafast Noon State (March 31, 2025) Retrieved from https://phys.org/news/2025-03-Quantum-superhighway-ultrafast-noon-tates.html
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