Saturday 15 March 2025
Scientists have made a significant breakthrough in understanding the behavior of dark-bright solitons, complex structures that can exist in superfluids like liquid helium or ultracold atomic gases. These solitons are fascinating because they can exhibit unusual properties, such as negative mass and oscillations under constant forces.
Dark-bright solitons are formed when a bright soliton, which is a localized wave of particles, collides with another bright soliton moving in the opposite direction. The resulting structure has a dark region where the density of particles is lower than its surroundings, surrounded by a bright region where the density is higher. This peculiar arrangement allows the soliton to maintain its shape and move through the superfluid without dissipating energy.
Researchers have long been interested in understanding how these solitons behave when subjected to external forces, such as a constant magnetic field or a linear potential. In particular, they wanted to know whether the solitons would oscillate back and forth under these conditions, much like a pendulum swings back and forth under gravity.
Previous studies have shown that dark-bright solitons can exhibit negative mass, meaning that they respond to forces in the opposite way of regular matter. For example, if you push on a normal object, it will move in the direction you’re pushing. But if you push on a dark-bright soliton with negative mass, it will actually move away from your hand.
The new study reveals that these unusual properties are linked to the oscillations of the solitons under constant forces. By analyzing the behavior of dark-bright solitons in a Bose-Einstein condensate, a state of matter where atoms or particles behave like a single entity, researchers found that they exhibit periodic oscillations when subjected to a linear potential.
These oscillations are reminiscent of the Josephson effect, which is a phenomenon where a supercurrent flows through a barrier between two macroscopic systems. In this case, however, the solitons are not flowing across a barrier but rather oscillating within the same system.
The researchers used advanced numerical simulations to model the behavior of dark-bright solitons and found that their oscillations are characterized by a self-adapted critical current and bias voltage. These parameters determine the amplitude and frequency of the oscillations, which can be tailored by adjusting the strength of the external force or the properties of the superfluid.
Cite this article: “Unveiling the Oscillatory Behavior of Dark-Bright Solitons in Superfluids”, The Science Archive, 2025.
Dark-Bright Solitons, Superfluids, Liquid Helium, Ultracold Atomic Gases, Negative Mass, Oscillations, Constant Forces, Linear Potential, Bose-Einstein Condensate, Josephson Effect
