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Holographic CFTs: The Dance of Gravity and Quantum Mechanics

Dive into the world of holographic theories shaping our understanding of the universe.

Jayashish Das, Arnab Kundu

― 6 min read


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When we talk about holographic Conformal Field Theories (CFTs) in two dimensions, we are diving into an exciting area of theoretical physics that combines elements of gravity with quantum mechanics. But don't worry if you're not a physicist; we'll break it down so that even your pet goldfish could get the gist.

The Basics: What is CFT?

A Conformal Field Theory is a type of quantum field theory that is invariant under conformal transformations. In simpler terms, it means that the rules of the theory don't change if you stretch or squish space—kinda like how your favorite pizza stays delicious no matter how you slice it.

In two dimensions, which is like flattening everything onto a piece of paper, these theories have unique properties that allow physicists to explore complex ideas without the clutter of higher dimensions. Imagine trying to find your way through a maze versus walking down a straight path with no obstacles. You get the idea.

Holography and Gravity: A Curious Pair

Now, add gravity into the mix. Thanks to a concept known as holography, these theories suggest that what happens in a three-dimensional space can be represented as a theory living on a two-dimensional boundary. Think of it like watching a 3D movie while only wearing 2D glasses. The action feels real, but the intricacies of the gravity field exist in a separate realm.

What’s Up with Bulk?

In this context, "bulk" refers to the extra dimensions where gravity plays a role, while the boundary is like the outside of the movie screen. The interplay between these two layers is where the fun begins, and we get to explore what happens when we "drive" our CFTs with some nifty complex protocols.

Driving the Theory: What Does It Mean?

Driving a CFT involves periodically changing the Hamiltonian, which is the operator that describes how a system evolves over time. Imagine it like a DJ remixing a song; they’ll drop beats in and out to create a different vibe. This remixing can lead to new behaviors within the system that don’t have an equivalent in a static setup.

Types of Driving

When we mention driving, we can run into three main behaviors depending on the parameters we set:

  1. Heating Phase: This is where things really heat up—figuratively and literally! The system enters a phase where energy levels soar.

  2. Phase Transition Line: Here, the system is balancing on a knife's edge, shifting between states as if it’s trying to decide what to wear to a party.

  3. Non-Heating Phase: In this state, the system might still have an Event Horizon, but it’s more like a lazy Sunday afternoon; no one is getting particularly heated, and energy levels stay relatively stable.

The Event Horizon: Where’s the Party?

One of the most intriguing aspects of this research is the event horizon, which you can think of as a boundary beyond which light cannot escape. In simpler terms, it’s like a black hole's edge.

How Does It Evolve?

When we apply our driving protocols, this event horizon can change dramatically. It can swell up rapidly in the heating phase, oscillate back and forth during the non-heating phase, or even rotate around like it’s grooving to a funky beat in the phase transition.

The Flowery Structure of Horizons

If you picture the event horizon in the heating phase, imagine a beautiful flower with petals that grow outward. Each petal corresponds to different peaks of energy, and as time passes, they unfurl toward the boundary like sunflower heads seeking sunlight.

The Role of Symmetry

Interestingly, the driving mechanism can break the symmetry of the event horizon. It’s like a perfect snowflake suddenly melting into a puddle—what was once a beautifully symmetrical form now has uneven edges. However, as time goes on, and if you wait long enough, some semblance of that original symmetry can emerge again.

Integral Curves: Path of the Observers

As we look deeper into the geometry of this setup, there are integral curves that represent the paths followed by imaginary observers existing within the bulk. You can think of them like a group of guests wandering around a party trying to make sense of the chaos.

Fixed Points: Where Do We End Up?

Eventually, these paths bring us to fixed points: places in this geometric landscape where observers would have no acceleration, essentially where they can rest. Imagine being able to lay back on a comfy couch and just enjoy the view of the room without worrying about the music getting too loud or someone stepping on your toes.

The Influence of Temperature

As we delve into the specifics, it becomes clear that starting with a Thermal State is crucial for observing how the event horizon transforms. In a thermal state, the system already has a built-in energy level, similar to a kettle already boiling water before you throw in some pasta.

How Does It All Fit Together?

The relationship between fluctuating temperatures and the conditions of the event horizon is vital. When you change the "temperature," it's like throwing in spices to a recipe. The final dish—our event horizon—changes flavor drastically depending on how you mix things up.

Practical Applications: Why Should We Care?

While playing with abstract concepts might seem overly theoretical, these models can help us understand real-world phenomena. The ideas explored in driven two-dimensional CFTs can shine light on more complex systems in condensed matter physics and black hole thermodynamics.

The Bigger Picture

By understanding how different states interact and evolve, scientists can ultimately learn about the universe's fabric, its beginnings, and perhaps even its fate. This knowledge could pave the way for future advancements in quantum computing, materials science, and beyond.

Conclusion: A Unique Journey

In summary, the world of driven two-dimensional holographic CFTs is rich and multifaceted. By examining how these theories evolve, we get a closer look at the intricate dance between gravity, energy, and quantum mechanics.

So, next time you hear about holography or CFTs, just remember: it's not just a bunch of scientists playing with complex math; they're exploring the hidden rhythms of the universe, much like a DJ crafting the perfect party track. Whether it’s a heated affair or a calm evening, there’s always something profound happening beneath the surface.

Original Source

Title: Flowery Horizons & Bulk Observers: $sl^{(q)}(2,\mathbb{R})$ Drive in $2d$ Holographic CFT

Abstract: We explore and analyze bulk geometric aspects corresponding to a driven two-dimensional holographic CFT, where the drive Hamiltonian is constructed from the $sl^{(q)}(2,\mathbb{R})$ generators. In particular, we demonstrate that starting with a thermal initial state, the evolution of the event horizon is characterized by distinct geometric transformations in the bulk which are associated to the conjugacy classes of the corresponding transformations on the CFT. Namely, the bulk evolution of the horizon is geometrically classified into an oscillatory (non-heating) behaviour, an exponentially growing (heating) behaviour and a power-law growth with an angular rotation (the phase boundary), all as a function of the stroboscopic time. We also show that the explicit symmetry breaking of the drive is manifest in a flowery structure of the event horizon that displays a $U(1) \to {\mathbb Z}_q$ symmetry breaking. In the $q\to \infty$ limit, the $U(1)$ symmetry is effectively restored. Furthermore, by analyzing the integral curves generated by the asymptotic Killing vectors, we also demonstrate how the fixed points of these curves approximate a bulk Ryu-Takayanagi surface corresponding to a modular Hamiltonian for a sub-region in the CFT. Since the CFT modular Hamiltonian has an infinitely many in-equivalent extensions in the bulk, the fixed points of the integral curves can also lie outside the entanglement wedge of the CFT sub-region.

Authors: Jayashish Das, Arnab Kundu

Last Update: 2024-12-24 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2412.18536

Source PDF: https://arxiv.org/pdf/2412.18536

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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