The Limits of Sequence Design: Scaling Laws for Quasi-Complementary Sets
New research establishes fundamental constraints on the scalability of quasi-complementary sequence sets, impacting codebook design and signal processing applications.
Science
Exotic Hadrons: Hunting Pentaquarks at High Energies
New theoretical tools promise to unlock the production rates of fully heavy pentaquarks, potentially revealing these elusive particles at the LHC and future collider experiments.
Unlocking Keystream Secrets: A New Attack on EChaCha20
![A steam cipher obscures information by combining plaintext with a keystream, effectively masking the underlying message and relying on the secrecy of both the key and the generation process to prevent decryption - a system perpetually vulnerable to entropy, as any compromise of the keystream reveals the original data [latex]P = C \oplus K[/latex].](https://arxiv.org/html/2604.13289v1/images/ks.png)
Researchers are leveraging the power of pattern recognition and machine learning to analyze the internal structure of the EChaCha20 stream cipher, opening new avenues for cryptanalysis.
Quantum Speedup for Reinforcement Learning
![The study demonstrates that even slight perturbations-an increase from [latex]\varepsilon = 2.47[/latex] to [latex]\varepsilon = 2.48[/latex]-can cause a system exhibiting an expected return of [latex]8.33[/latex] over a horizon of eight steps to transition between distinct optimal policies, revealing a critical value [latex]\varepsilon^{\*} \in (2.47, 2.48)[/latex] where multiple solutions with a maximum return of approximately 0.644 coexist, highlighting the inherent fragility of optimality in complex systems.](https://arxiv.org/html/2604.13096v1/contour_4level8_2-48_1.png)
New analytically solvable models reveal how quantum control can dramatically reduce the computational cost of training intelligent agents.
Echoes of Chaos: Quantum Scars Emerge in Driven Many-Body Systems
![Driven Floquet systems exhibit quantum scars-stable states defying typical thermalization-where the mean overlap between initial states and energy eigenstates exceeds random matrix theory predictions, mirroring classical stability boundaries determined by Lyapunov exponents and appearing prominently near driving frequencies of [latex]\omega_{s} = 0[/latex] and π, a phenomenon distinct from the behavior of generic random states which remain closely aligned with random matrix theory expectations across all parameter space.](https://arxiv.org/html/2604.13164v1/x1.png)
New research reveals the surprising persistence of quantum scarring-a hallmark of underlying classical structure-even within the complex dynamics of periodically driven many-body systems.
Squeezing More Out of Less: Ultra-Low-Bit Quantization for Large Language Models
A new method enables accurate and robust compression of massive language models down to extremely low bit-widths without significant performance loss.
Hiding in the Noise: Secure Quantum Communication Under Uncertainty
![A communication scheme leverages a beamsplitter channel-where Bob receives a signal with transmittance η and an eavesdropper, Willie, receives [latex]1-\eta[/latex]-and enforces covertness by ensuring Willie’s observations are statistically indistinguishable from thermal noise.](https://arxiv.org/html/2604.13116v1/x1.png)
New research provides a rigorous framework for ensuring secure quantum communication even when the transmission channel is imperfectly known.
Beyond Encryption: Securing 6G for the Quantum Era
The rollout of 6G networks demands a proactive overhaul of security regulations to address emerging quantum threats and ensure long-term resilience.
Outsmarting AI: A New Test for Language Model Security
![Under a configuration of [latex]T=0.3[/latex] and [latex]L=256[/latex], comparative analysis reveals that dual-space strategies consistently outperform both semantic-only and character-only approaches across varying query budgets when evaluated on the MSR, AQS, and Stealth datasets.](https://arxiv.org/html/2604.12548v1/x5.png)
Researchers have developed a novel framework to rigorously evaluate how well large language models withstand subtle, cleverly disguised attacks designed to manipulate their responses.
Taming Cosmic Chaos: A New Twist on the Mixmaster Universe
![Despite differing initial conditions within the Loop Algebra, the point universe’s trajectory in phase space ([latex]\mathcal{H}\_{i},\theta\_{i})[/latex] demonstrates a remarkable insensitivity, converging over 25 iterations as energy consistently decreases and the angle oscillates briefly before stabilizing.](https://arxiv.org/html/2604.12760v1/x3.png)
Researchers have shown that modifying the fundamental rules of quantum mechanics can effectively dampen the chaotic behavior predicted for the early universe.