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The Interaction of Superconductors and Quasicrystals

Exploring superconducting effects on non-Hermitian quasicrystals and their unique behaviors.

Shaina Gandhi, Jayendra N. Bandyopadhyay

― 6 min read


Superconductors Meet Superconductors Meet Quasicrystals non-Hermitian materials. Examining unique behaviors in
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In the world of physics, there are many cool things to discover, especially when we talk about Superconductors and Quasicrystals. Today, we're diving into how superconducting pairing affects these Non-Hermitian quasicrystals. Buckle up; it’s going to be a fascinating ride!

What Are Superconductors and Quasicrystals?

Superconductors are materials that can conduct electricity without any resistance when they are cooled down to very low temperatures. Think of it as a highway for electrons without any speed bumps or traffic jams. Meanwhile, quasicrystals are a unique type of material that don’t have a regular repeating pattern like traditional crystals, making them a bit like a beautiful, complex mosaic.

Non-Hermitian Systems: The Unusual Cousins

Now, enter the non-Hermitian systems, which are like those quirky relatives that show up at family gatherings. They don’t follow the same rules as regular systems and can have some pretty wild behaviors, especially concerning energy levels. In non-Hermitian systems, energy can be complex, meaning it has both a real part and an imaginary part. Sounds complicated, but in simpler words, it just means things can get a bit weird!

The Dance of Hopping and Pairing

In our exploration, we focus on how particles hop in these systems. In physics, "hopping" refers to how particles can move from one spot to another. The hopping can be short-range (like jumping to a neighbor’s house) or long-range (like teleporting across the city). When we add superconducting pairing into the mix, it’s like adding some funky dance moves to this hopping party.

Short-Range Hopping

When particles hop only to their immediate neighbors, they do so in a rather orderly fashion. At first, if we look at the pairing effects, we see that weak pairing leads to what we call quasi-Majorana Modes, which are like wiggly dance moves that don’t settle down. As we turn up the pairing strength, these modes start to localize at the edges, much like how the best dancers find their spots on the stage.

Long-Range Hopping

Now, if we allow our particles to hop long distances, things get more interesting. With weak pairing, we see a behavior similar to the quasi-Majorana modes, but now they start to dance around much more energetically! As pairing strength increases, the behavior changes, and we see what we call massive Dirac modes, which are like heavyweight champions in the dance-off, bringing a whole new level of energy to the floor.

Goodbye Plateaus!

In our study, we notice something curious about the plateaus seen in the energy levels of these systems. These plateaus are like the steady spots on a rollercoaster where the ride is calm. However, when superconducting pairing kicks in, these plateaus start to disappear as pairing strength increases. It’s like the rollercoaster is suddenly on a wild twisty ride, leaving the calm spots behind!

The Phase Diagram: Mapping the Changes

To help us understand how these changes happen, we create something called a phase diagram. This diagram serves as a map, showing how the energy levels and localization properties change with different pairing strengths and hopping ranges. It’s like a treasure map guiding us through the land of superconductors and quasicrystals, where we can find the hidden jewels of knowledge.

Anderson Localization: The 'No Go' Zone

To better grasp what’s going on, we can't forget about a significant concept called Anderson localization. Back in the 1950s, a clever physicist named P. W. Anderson discovered that in certain random lattice structures, particles can become completely localized. This means they don’t go anywhere. Imagine being stuck in a traffic jam on a highway with no exit. It’s a bummer for the electrons, for sure!

In simpler terms, localization means that even if there is some disorder in the system, particles can be stuck in states instead of spreading out. This concept is essential for understanding how superconductors work, especially in the presence of disorder.

Transitioning States: From Delocalized to Multifractal

As we look deeper into our phase diagram, we notice transitions from delocalized states to multifractal states. Delocalized states are the ones that spread nicely throughout the material, while multifractal states are a bit of a jumble, like a mixed bag of candy.

In our explorations, we find that as pairing strength increases, some states start to show multifractal behavior. This is akin to the sweet moment when candy becomes a mixture of flavors instead of just one. It makes the study extra tasty!

Fractal Dimensions: Measuring the Complexity

One way to understand how complex these multifractal states are is by using something called fractal dimensions. Imagine measuring how intricate and twisty a path is in a park. A simple path has a low dimension, while a complex one, filled with twists and turns, has a higher dimension.

By calculating these fractal dimensions for different energy eigenstates, we can better understand how pairing influences the hopping mechanisms within our non-Hermitian quasicrystals.

A Peek Into the Future: The Real-to-Complex Transition

As we venture further into the non-Hermitian systems, we notice something unexpected: a real-to-complex transition. As pairing becomes stronger, the energy spectrum starts flipping from real values to complex values. This transition can be likened to a magician pulling a rabbit out of a hat, surprising everyone in the audience.

In our diagrams, we can pinpoint the regions where this magical transformation occurs, providing insights into the behavior of these fascinating systems.

Majorana Modes: The Star Performers

In the spotlight of our study, we have the Majorana zero modes. These modes are the rockstars of our quasicrystal dance party. They come and go, depending on the pairing strength and hopping types. With short-range hopping, Majorana modes show oscillating behavior, but with stronger pairing, they become localized at the edges, making them stand out even more.

The Impact of Non-Hermiticity

As we explore the effects of non-Hermiticity, we find that even these eccentric characteristics affect the system. The unique properties of non-Hermitian systems, like the skin effect and exceptional points, create even more layers of complexity in our study.

Conclusion: A Dance of Science

To wrap up this delightful journey through superconducting effects on non-Hermitian quasicrystals, we’ve uncovered various fascinating phenomena. From the oscillating modes to the disappearing plateaus, each step of our exploration reveals the intricate dance of particles and their peculiar behaviors.

As we continue to study these systems, we can imagine many more exciting discoveries on the horizon. The world of physics is vast, and as we peel back the layers, who knows what delightful surprises await? So next time you think of superconductors and quasicrystals, remember they are not just scientific concepts; they are an energetic dance full of twists and turns!

Original Source

Title: Superconducting $p$-wave pairing effects on one-dimensional non-Hermitian quasicrystals with power law hopping

Abstract: We study the effects of superconducting $p$-wave pairing on the non-Hermitian Aubry-Andr\'e-Harper model with power-law hopping. For the case of short-range hopping, weak pairing leads to oscillating quasi-Majorana zero modes, turning to edge-localized Majorana zero modes as pairing strength increases. For the case of long-range hopping, we observe the emergence of massive Dirac modes having oscillatory behavior, similar to Majorana modes with weak pairing. The massive Dirac modes localize at the edges as the pairing strength grows. The superconducting pairing spoils the plateaus observed in the fractal dimension of all the energy eigenstates of the Aubry-Andr\'e-Harper model with power-law hopping. The number of plateaus decreases with the increasing pairing strength for the weak non-Hermiticity in the system. The phase diagram of the system reveals that real and complex energy spectrums correlate differently with the localization properties of the eigenstates depending on the strength of pairing and hopping range.

Authors: Shaina Gandhi, Jayendra N. Bandyopadhyay

Last Update: Nov 21, 2024

Language: English

Source URL: https://arxiv.org/abs/2411.14144

Source PDF: https://arxiv.org/pdf/2411.14144

Licence: https://creativecommons.org/licenses/by/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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