Transitioning Wave Functions in Symmetric Quantum Systems
Explore the behavior of wave functions in symmetric quantum systems and their phase transitions.
― 5 min read
Table of Contents
- Understanding Wave Functions
- The Basics of Symmetric Systems
- Different Phases in Symmetric Systems
- The Role of Complex Potentials
- Localization and Its Effects
- Tools for Measuring Complexity
- Observing the Transition
- Time Evolution and Localization
- Comparing Phases
- The Role of Initial States
- Measuring Localization Strength
- The Importance of Dynamics
- Conclusion
- Original Source
In this article, we will discuss the behavior of certain quantum systems that have a special kind of symmetry. These systems can show different states depending on certain parameters. We will focus on how the spread of Wave Functions, which represent the possible states of these systems, varies when we change specific conditions.
Understanding Wave Functions
Wave functions are like fingerprints of a quantum system. They describe the likelihood of finding a particle in various places. When we talk about the spreading of wave functions, we mean how the probability of these particles being in certain places changes over time.
The Basics of Symmetric Systems
Symmetric systems have a special quality that makes them unique. In these systems, if we flip them around or change their direction, they still look the same. This kind of symmetry is useful for understanding how particles behave in certain situations.
Different Phases in Symmetric Systems
In symmetric systems, we can observe two main phases:
Unbroken Phase: In this phase, the wave functions are spread out over the entire area. The particles do not localize in one spot but are distributed across the space.
Broken Phase: Here, the wave functions tend to be more localized. This means that the particles gather in specific areas rather than being spread out.
The transition between these two phases is what we will focus on.
The Role of Complex Potentials
In our symmetric systems, we introduce complex potentials at certain points, specifically at the edges. This addition can influence the behavior of the wave functions, leading to interesting phenomena such as Localization.
Localization and Its Effects
Localization refers to the tendency of particles to group in specific areas. In the broken phase, particles will be found mainly around one edge of the system instead of being evenly distributed. This leads to what is known as the non-Hermitian skin effect, where wave functions tend to be found more on one boundary.
Tools for Measuring Complexity
To analyze how wave functions spread and localize, we use several measures:
Spread Complexity: This is a way to quantify how spread out the wave function is over time. In the unbroken phase, the spread complexity will show an initial increase, but in the broken phase, it will stabilize at a lower value due to localization.
Entropic Complexity: This measure also helps us understand the spread of wave functions. It estimates how many states are needed to describe the wave function appropriately.
Krylov Inverse Participation Ratio (KIPR): This is another tool to measure localization. A higher value indicates stronger localization, helping us understand how the wave functions behave over time.
Observing the Transition
As we change the parameters of our symmetric system, we can witness a transition from the unbroken phase to the broken phase. Initially, in the unbroken phase, the wave functions are spread out. However, as we adjust certain settings, we start to see the wave function becoming localized. This transition is crucial for understanding the dynamics within these systems.
Time Evolution and Localization
As time progresses, we monitor how the wave functions evolve. In the unbroken phase, the wave function will spread out and oscillate between locations. In contrast, during the broken phase, the wave function will quickly localize on one edge, corresponding to the non-Hermitian skin effect.
Comparing Phases
In the Unbroken Phase:
- The wave function is spread out.
- Complexity values increase but may stabilize at higher levels.
In the Broken Phase:
- The wave function tends to localize.
- Complexity values are suppressed due to localization.
The Role of Initial States
The initial state we choose affects how the wave function behaves. Depending on where we start, we can see different levels of localization and complexity. For example, if the initial state covers a larger area, it may lead to different spreading outcomes compared to a state localized in one part.
Measuring Localization Strength
We have established that KIPR is an effective way to measure localization strength. By evaluating the values of different complexities and KIPR, we can gain insights into how the system transitions from unbroken to Broken Phases. The KIPR will increase in value when the wave functions become more localized.
The Importance of Dynamics
Understanding how these wave functions change over time provides a deeper insight into quantum mechanics. The dynamics of spreading and localization give us clues about how information spreads and how quantum systems behave under different scenarios.
Conclusion
In summary, symmetric quantum systems exhibit a fascinating transition between different states. By studying how wave functions spread and localize, we gain a better understanding of the underlying physics. The measures we use, including spread complexity, entropic complexity, and KIPR, allow us to explore these transitions effectively. This exploration can lead to new insights in the field of quantum mechanics, opening doors for future research and applications.
Title: Spread complexity and localization in $\mathcal{PT}$-symmetric systems
Abstract: We present a framework for investigating wave function spreading in $\mathcal{PT}$-symmetric quantum systems using spread complexity and spread entropy. We consider a tight-binding chain with complex on-site potentials at the boundary sites. In the $\mathcal{PT}$-unbroken phase, the wave function is delocalized. We find that in the $\mathcal{PT}$-broken phase, it becomes localized on one edge of the tight-binding lattice. This localization is a realization of the non-Hermitian skin effect. Localization in the $\mathcal{PT}$-broken phase is observed both in the lattice chain basis and the Krylov basis. Spread entropy, entropic complexity, and a further measure that we term the Krylov inverse participation ratio probe the dynamics of wave function spreading and quantify the strength of localization probed in the Krylov basis. The number of Krylov basis vectors required to store the information of the state reduces with the strength of localization. Our results demonstrate how measures in Krylov space can be used to characterize the non-hermitian skin effect and its localization phase transition.
Authors: Aranya Bhattacharya, Rathindra Nath Das, Bidyut Dey, Johanna Erdmenger
Last Update: 2024-06-05 00:00:00
Language: English
Source URL: https://arxiv.org/abs/2406.03524
Source PDF: https://arxiv.org/pdf/2406.03524
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.