Discover how quantum simulations let researchers observe Josephson dynamics and Shapiro steps using atomic systems instead of electronic devices.
Quantum electronic components such as Josephson junctions underpin voltage standards and quantum computing, but the microscopic processes inside superconductors are difficult to observe directly. This limits experimental access to some of the fundamental quantum effects that govern these devices.
Researchers at Rheinland Pfälzische Technische Universität Kaiserslautern Landau have demonstrated an alternative approach by recreating the Josephson effect using ultracold atoms. Instead of electrons moving through superconductors, the team used a quantum simulation based on Bose Einstein condensates separated by a thin optical barrier formed by laser light.
In the experiment, two condensates were divided by a focused laser beam that acted as an atomic scale junction. By moving this barrier in a controlled periodic manner, the researchers reproduced conditions comparable to a Josephson junction exposed to microwave radiation. The atomic system exhibited Shapiro steps, which are quantized voltage plateaus that define the international voltage standard in superconducting devices.
The appearance of Shapiro steps in this atomic platform indicates that the underlying physics of the Josephson effect does not depend on the specific material system. Instead, it reflects more general quantum mechanical principles that apply across different physical implementations.
The work demonstrates how quantum simulation can make otherwise inaccessible quantum scale behavior observable. By transferring electronic phenomena into atomic systems, researchers can directly visualize excitations and test whether key effects are universal rather than material specific.
Key technical highlights include:
- Quantum simulation of a Josephson junction using ultracold atoms
- Optical barrier created and modulated using laser light
- Observation of Shapiro steps in an atomic system
- Direct visualization of quantum excitations
- Validation of universality in Josephson physics
Herwig Ott, who led the experimental team, says, “In our experiment, we were able to visualize the resulting excitations for the first time. The fact that this effect now appears in a completely different physical system than an ensemble of ultracold atoms confirms that Shapiro steps are a universal phenomenon.”
