Superconductivity, the phenomenon of conducting electrical current with negligible resistance, has long fascinated scientists and engineers due to its potential applications in various electronic and energy devices. In recent years, researchers in the field of condensed-matter physics and material science have been actively investigating strategies to enhance the superconductivity of specific materials. One such material is K3C60, an organic superconductor that exhibits zero resistance when subjected to mid-infrared optical pulses.
With the goal of enhancing light-induced superconductivity in K3C60, a group of researchers from the Max Planck Institute for the Structure and Dynamics of Matter, Università degli Studi di Parma, and University of Oxford embarked on a study that yielded fascinating results. Their findings, published in Nature Physics, demonstrate a strategy that significantly enhances the photo-susceptibility of K3C60 by two orders of magnitude.
For over a decade, the research team, including Andrea Cavalleri, has been investigating the use of light to enhance superconductivity from an equilibrium state above Tc (critical temperature). Cavalleri explains, “We have shown that this works in some cuprates, in certain charge transfer salts and in K3C60.” In their previous experiments, they successfully induced a superconducting phase in K3C60 using excitation photon energies ranging from 80 to 165 meV (20–40 THz). However, they aimed to explore lower energies, between 24 and 80 meV (6–20 THz), which had not been accessible to them until now.
A New Approach with Remarkable Results
To achieve their goal, the researchers utilized a terahertz source capable of generating narrow-bandwidth pulses by combining the near-infrared signal beams of two distinct phase-locked optical parametric amplitudes. This new approach allowed them to investigate the excitation of K3C60 at lower energy levels.
Cavalleri highlights the significance of their findings, stating, “The underlying physics is not yet clear, but the experiment targets selected molecular vibrations that are driven directly to large amplitudes at their resonance frequency.” This interaction between the driven vibrations and electronic states appears to enhance the pairing and coherence necessary for superconductivity. The researchers discovered that the effect is particularly effective at 10 THz, coinciding with a specific molecular vibration.
The recent breakthrough by Cavalleri and his collaborators sheds new light on the mechanisms driving photo-induced superconductivity in K3C60 and other superconductors. Moreover, their work introduces a strategy that has the potential to extend the duration of photo-induced superconductivity, opening up exciting possibilities for the development of light-driven quantum technologies.
Cavalleri further shares the remarkable potential of their discovery, stating, “We realized a 10 ns long-lived superconducting state at room temperature. In principle, this could be used for future quantum devices powered by light.” The implications of this breakthrough are indeed significant, as it paves the way for the creation of innovative quantum devices that harness the power of light.
A Promising Path Forward
While there is still much to uncover in terms of the underlying physics and mechanisms at play, the recent study represents a critical step forward in the quest to enhance superconductivity using light. The ability to manipulate and extend the duration of photo-induced superconductivity could revolutionize various fields, including energy storage, quantum computing, and communication.
As scientists and engineers continue to explore the possibilities of superconductivity, breakthroughs like the one achieved by Cavalleri and his team serve as reminders of the incredible potential that lies ahead. The journey to unlock the true capabilities of superconducting materials not only fuels scientific curiosity but also promises to shape the future of technology.