Science – Page 9

Beyond the Limits of Quantum Coherence

06.12.2025 by pricpr

New research explores the surprising potential for amplifying a fragile quantum property, and defines the boundaries of its enhancement under realistic constraints.

Beyond Equilibrium: Universal Signatures of Quantum Phase Transitions

06.12.2025 by pricpr

$The study of the dissipative Dicke model reveals that near the critical point, the thermodynamic metric $ζ$ scales according to $ζ \sim |g - g_{c}|^{x}$, with a numerically determined exponent of $x = -2.9953 \pm 0.0009$ - a value remarkably consistent with the theoretical prediction of $x = -(\alpha + \gamma)$, given parameters $\alpha = 2$ and $\gamma = 1$.$

New research reveals a unifying principle governing how quantum systems transition between phases, even when driven far from equilibrium.

Beyond Hermiticity: A Dissipative Spin Liquid Model Unveiled

06.12.2025 by pricpr

$The study demonstrates that the Liouvillian spectrum-analyzed for systems with linear sizes ranging from 4 to 64-reveals a phase transition point, $\gamma_{PT}$, which scales inversely with system size ($1/L$), while a critical value, $\gamma^*$, remains approximately constant at $3J/4$, and the fraction of broken $\mathcal{PT}$ symmetry smoothly transitions from 0 to 1 as the parameter $\gamma$ crosses these thresholds.$

Researchers have discovered an exactly solvable model demonstrating how non-Hermitian dynamics can give rise to exotic quantum phenomena in dissipative spin liquids.

When Perturbation Fails: Taming Light in Complex Cavities

06.12.2025 by pricpr

$A ring cavity, incorporating a dispersing medium, modulates the propagation of a pulsed light field $E_i(t,z)$ pumped through an input-output mirror with reflection coefficient $\sqrt{\mathcal{R}}$ and transmission coefficient $\sqrt{\mathcal{T}}$, effectively creating a round-trip time $T_{R}$ that governs the cavity’s dispersive response.$

A new analysis reveals the limits of simplified modeling techniques used to predict how light pulses behave within dispersive optical cavities.

Smarter Inference: Guiding Language Models with Real-Time Rewards

06.12.2025 by pricpr

A new approach selectively builds upon promising generations during inference, boosting performance beyond traditional methods.

Bridging Microwaves and Light: A New Path to Quantum Networks

06.12.2025 by pricpr

Researchers demonstrate a promising pump-free method for converting microwave signals into optical photons, a critical step towards building long-distance quantum communication systems.

Untangling Qubit Control: A Bayesian Approach

06.12.2025 by pricpr

$Stepwise two-parameter estimation, utilizing prior distributions with a width of $5^{\circ}$, demonstrates that the accuracy of shift estimation-indicated by a standard deviation of $\Delta\gamma$-approaches the classical Van Trees limit as a function of angle $\theta$, while axis estimation accuracy, similarly assessed with $\Delta\theta$, closely aligns with the theoretical prediction and remains consistent with the diagonal, signifying effective parameter recovery.$

New research explores a practical method for precisely calibrating multiple qubit rotations using Bayesian inference.

Simulating the Universe’s Instability: A Quantum Leap for Vacuum Decay Studies

06.12.2025 by pricpr

A programmable Rydberg atom array simulates the decay of a false vacuum, mirroring the behavior of an antiferromagnetic Ising model where staggered detuning creates a metastable state susceptible to quantum tunneling and the nucleation of true vacuum bubbles, effectively demonstrating a physical analogue of vacuum instability.

Researchers have successfully used a programmable array of Rydberg atoms to model the process of false vacuum decay, offering a new platform to explore fundamental questions about the stability of the universe.

Taming the Unstable: Universal Control of Quantum Systems

05.12.2025 by pricpr

$Through manipulation of a $PT$-symmetric Hamiltonian within a cavity-magnonic system, Fock-state transfer-specifically transitioning from $|5\rangle_a|0\rangle_b$ to $|0\rangle_a|5\rangle_b$-demonstrates fidelity regardless of whether exceptional points are avoided or crossed, a result achieved by dynamically constraining coherent coupling strength $J(t)$ and detuning $\Delta(t)$ via a time-dependent parameter $\theta(t)$, and ensuring the preservation of initial and final state differences $f_i(\tau) - f_i(0) = 0$ under conditions where $\varphi_a = \pi$, $\varphi = \pi/2$, $\Gamma = 0$, and $\gamma_a = \gamma_b$ satisfies a defined relationship with $\lambda$ dependent on whether exceptional points are avoided ($\lambda = \pi$) or crossed ($\lambda = 4\pi$).$

Researchers have developed a new framework for controlling non-Hermitian quantum systems, overcoming limitations imposed by their inherent instability.

Hunting Dark Matter with the Universe’s First Light

05.12.2025 by pricpr

$The study establishes increasingly stringent upper limits on the cross-section for interactions between dark matter and baryonic matter-represented by the parameter $σ\_0$-with projections indicating that a five-year mission will significantly refine these bounds, potentially surpassing current constraints derived from cosmic microwave background observations, though sensitivity remains dependent on galactic population parameters.$

An upcoming 21cm cosmology experiment, Hongmeng, promises to sharpen our search for interactions between dark matter and ordinary matter.