Moiré Heterostructures Achieve Superconductivity Without Attraction

Researchers have proposed a novel pathway to achieving superconductivity in a bilayer moiré heterostructure, circumventing the need to amplify attractive forces between electrons, a longstanding challenge in the field. The work, authored by Tsung-Sheng Huang of the Joint Quantum Institute at the University of Maryland and colleagues from ETH Z¨urich and University of Cologne, details how superconductivity emerges as a stable, stationary state. The key ingredient is a bilayer moiré platform in which the layer degree of freedom acts as a pseudospin, allowing the pseudospin structure required for pairing to be implemented through optically induced spatial operations. In contrast, under conditions of collective dissipation, the same platform exhibits an early-time superradiant burst. The results establish driven-dissipative moiré heterostructures as a promising platform for preparing superconductivity, while also revealing a connection between steady-state pairing and transient superradiance.

Moiré Heterostructure Enables Dissipative Superconductivity

A surprising new pathway to achieving superconductivity, one that bypasses the need for strong electron attraction, has been detailed in recent work, potentially reshaping materials science. Researchers have reported on an approach utilizing a bilayer moiré heterostructure, a carefully constructed material where layers interact to create unique electronic properties, to induce superconductivity through dissipation rather than conventional electron pairing mechanisms. This design challenges established thinking, as it suggests superconductivity can arise even without increasing the attractive forces between electrons. The key ingredient is a bilayer moiré platform in which the layer degree of freedom acts as a pseudospin, allowing the pseudospin structure required for pairing to be implemented through optically induced spatial operations. This preparation scheme requires local dissipation, which arises naturally from weakly dispersive bosonic modes in the heterostructure.

This intricate control is achieved through a combination of Raman transitions and the exploitation of hyperbolic phonon-polaritons (HPPs) within hexagonal boron nitride (hBN) layers sandwiched by a moiré transition metal dichalcogenide (TMD) homobilayer. These HPPs, possessing a nearly nondispersive sector, ensure locality and suppress interference that would otherwise hinder the emergence of superconductivity. The platform exhibits different behavior depending on the dissipation regime; carefully engineered local dissipation leads to a stable, steady-state superconductivity, while a shift to collective dissipation results in a transient superradiant burst, a sudden emission of energy. “In the complementary regime where photons mediate the emission, we find the emergence of collective radiation, manifested as an early-time burst in the photoemission rate,” the source reports. This unexpected connection between steady-state pairing and transient superradiance suggests a deeper, unifying principle governing these seemingly disparate phenomena, with interference in dissipation acting as a crucial control parameter. The team’s theoretical framework, based on a Lindblad dynamics, demonstrates that the system can be steered into a BCS paired state at long times, effectively creating a superconducting state through driven-dissipative evolution.

Optically-Driven Pseudospin Control for Pairing

Beyond conventional approaches to achieving superconductivity, typically focused on maximizing electron attraction, researchers are now exploring pathways that circumvent the need for strong attractive interactions. A novel strategy, detailed in recent work, proposes a driven-dissipative protocol to prepare superconductivity as a stable state within a two-dimensional moiré heterostructure. This design fundamentally relies on a bilayer moiré platform where the layer itself functions as a “pseudospin,” allowing the pseudospin structure required for pairing to be implemented through optically induced spatial operations. The core of this approach centers on engineering dissipation, removing energy from the system, to stabilize the superconducting state.

The researchers numerically confirmed that this dissipative dynamics consolidates a BCS paired state over time, demonstrating a pathway to superconductivity without relying on enhanced electron attraction. “We engineer a Lindblad dynamics on a 2D bipartite lattice, where the time evolution of the system density operator is governed by,” explains the study, outlining the theoretical framework. When photons, rather than HPPs, mediate the emission process, the heterostructure displays an early-time superradiant burst, a rapid emission of energy, contrasting sharply with the steady-state superconductivity achieved through localized dissipation via HPPs. The ability to switch between photonic and HPP-mediated emission offers tunability, revealing the potential to control the system’s behavior.

Weakly Dispersive HPPs Facilitate Local Dissipation

Mohammad Hafezi and colleagues at the Joint Quantum Institute and ICFO-Institut de Ciencies Fotoniques are reporting on a novel approach to achieving superconductivity, not by intensifying electron attraction, but by carefully engineering how energy dissipates within a specially constructed material. Their work centers on bilayer moiré heterostructures, meticulously layered materials designed to host superconductivity through controlled dissipation, a departure from conventional methods. This innovative strategy addresses a key challenge in the field: achieving long-lived superconducting order without relying on increasingly complex methods of strengthening electron interactions. The researchers demonstrate that by combining HPPs with Raman processes, optical transitions that do not manipulate the material’s properties, they can effectively guide the system toward a BCS paired state, the hallmark of superconductivity. Crucially, the choice of dissipation mediator, whether photons or HPPs, drastically alters the system’s behavior.

The team discovered that while photons initially do not appear promising as energy dissipators, their nonlocal character interferes with the formation of a stable superconducting state. To overcome this, they turned to hyperbolic phonon-polaritons (HPPs). This design offers tunability, offering the potential to switch between different emitted modes and, consequently, control the degree of interference within the dissipators.

Raman Transitions and Bosonic Emission Induce Pairing

The pursuit of room-temperature superconductivity has taken a surprising turn, with researchers reporting a pathway that bypasses the need for strong electron-electron attraction. A new theoretical framework, detailed in recent work, suggests that superconductivity can be induced in specifically engineered bilayer moiré heterostructures through a carefully orchestrated interplay of light and material properties. The work, led by Tsung-Sheng Huang of the Joint Quantum Institute at the University of Maryland and colleagues, proposes using Raman transitions, driven by external light sources, to couple electrons within the moiré superlattice and facilitate the emission of bosonic modes. The key ingredient is a bilayer moiré platform in which the layer degree of freedom acts as a pseudospin. The team discovered that while photons initially appear promising as energy dissipators, their nonlocal character interferes with the formation of a stable superconducting state; to overcome this, they turned to hyperbolic phonon-polaritons (HPPs) within the hBN layers.

Numerical simulations confirm that this combination of Raman transitions and HPP emission consolidates a BCS paired state at longer timescales. While local dissipation via HPPs leads to steady-state superconductivity, collective dissipation mediated by photons results in a transient superradiant burst, an early-time emission of radiation. The results establish driven-dissipative moiré heterostructures as a promising platform for preparing superconductivity, while also revealing a connection between steady-state pairing and transient superradiance.

Conventional approaches to achieving superconductivity often center on bolstering the attractive forces between electrons, yet a newly proposed strategy flips this paradigm by focusing instead on carefully engineered dissipation. Researchers are reporting that superconductivity can arise not from increasing attraction, but from skillfully removing energy from a system, with results establishing a stable, paired state through controlled loss. This work, detailed in recent findings, proposes a driven-dissipative protocol utilizing a unique bilayer moiré heterostructure as the foundation for this unconventional superconductivity. This platform isn’t simply about achieving superconductivity; it reveals a surprising duality. This connection is established by carefully controlling the mediators of dissipation. Initial attempts to utilize photons as the loss mechanism were hampered by their nonlocal character on the superlattice scale, leading to destructive interference. The solution, according to the findings, involves sandwiching the TMD layers within hexagonal boron nitride (hBN) sheets and exploiting hyperbolic phonon-polaritons (HPPs).

Controlling how energy dissipates within a novel material platform offers an unexpected pathway toward achieving superconductivity without relying on traditional methods of boosting electron attraction. Researchers have demonstrated a driven-dissipative protocol utilizing a bilayer moiré heterostructure to prepare a superconducting state, a departure from conventional approaches that focus on increasing the forces binding electrons together. This innovative strategy centers on carefully engineering how energy leaves the system, effectively guiding it toward a superconducting state in steady state. Crucially, the team discovered that interference among emitted modes can hinder the emergence of superconductivity if photons are used as the primary means of energy dissipation. This design allows for tunability, offering the potential to switch between different emitted modes and, consequently, control the degree of interference within the dissipators.