In a groundbreaking experiment, scientists have confirmed the superfluid properties of supersolids by observing the formation of quantized vortices—mini-tornadoes in a quantum gas. This breakthrough offers new insights into the coexistence of solid and fluid characteristics in these exotic states of matter, opening up exciting possibilities for the study of quantum systems and astrophysical phenomena.
The concept of supersolids—materials that simultaneously exhibit the rigidity of solids and the fluidity of superfluids—may seem paradoxical. However, more than 50 years ago, physicists predicted that quantum mechanics could allow such a state. As Francesca Ferlaino, from the University of Innsbruck and the Institute of Quantum Optics and Quantum Information (IQOQI), explains, “A supersolid is both rigid and liquid, much like Schrödinger’s cat, which is both alive and dead.”
While scientists have previously observed the crystalline structure that imparts the “solid” qualities to supersolids, direct evidence of their superfluid properties remained elusive. In particular, the presence of quantized vortices—hallmarks of superfluid flow—had not been observed. This gap in knowledge has now been filled with a major breakthrough, where quantized vortices were successfully detected in a rotating two-dimensional supersolid.
The experiment, led by Eva Casotti, was a significant leap forward in quantum research. The team had previously achieved a major feat in 2021 by creating the first long-lived two-dimensional supersolid using ultracold erbium atoms. The next step—stirring the supersolid to induce superfluid behavior—was far more challenging, as the delicate state of the supersolid could easily be disrupted.
To overcome this challenge, the researchers used high-precision techniques guided by theoretical models. Magnetic fields were employed to gently rotate the supersolid, a process that caused the formation of quantized vortices—hydrodynamic signatures of superfluidity. As liquids do not rotate rigidly, this observation provided clear evidence of superfluid flow within the supersolid, offering a significant advancement in the study of quantum matter.
“This work is a significant step forward in understanding the unique behavior of supersolids and their potential applications in the field of quantum matter,” remarked Ferlaino, emphasizing the importance of this discovery in the broader landscape of quantum research.
The implications of this discovery are far-reaching. Beyond its importance in condensed matter physics, the research could offer insights into exotic quantum phases found in astrophysical phenomena. For instance, similar superfluid phases are believed to exist under the extreme conditions inside neutron stars. The rotation glitches observed in these stars—sudden changes in their rotational speed—are thought to be caused by superfluid vortices trapped inside.
“Our findings open the door to studying the hydrodynamic properties of exotic quantum systems with multiple broken symmetries, such as quantum crystals and even neutron stars,” said Thomas Bland, who guided the theoretical development of the project. The ability to replicate such phenomena on Earth using supersolids in the lab provides a unique opportunity to study them under controlled conditions.
The discovery also has potential applications in other fields, such as superconductivity, where superfluid vortices are thought to exist in superconductors that can conduct electricity without loss.
“This work is an important milestone on the way to investigating new physics,” says Ferlaino. “We can now observe phenomena that only occur in nature under extreme conditions, such as inside neutron stars, right here in the lab.”
By observing the behavior of supersolids and their vortices, scientists are not only advancing our understanding of quantum mechanics but also unlocking the potential to study and simulate extreme physical phenomena that are otherwise inaccessible.
By Impact Lab
