physics6.55 min read
Hidden Synchrony: Two Quantum Clocks Align via Dissipation in Trapped Ions
11 days ago•Source: American Physical Society
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8.885 min•18 days ago
Bootstrapping String Theory: From Minimal Constraints to a Unique High-Energy Description
A bootstrap analysis shows that, under ultrasoft high-energy behavior and the assumption that Regge zeros are the only zeros, the 4- and 5-point scattering amplitudes for identical scalars are uniquely fixed to the string-theory form, implying string dynamics may emerge from fundamental consistency principles rather than being assumed a priori. Built on Lorentz invariance, crossing symmetry, positivity, and analyticity, the result supports string universality but depends on whether these inputs can be independently justified or if other assumptions yield the same outcome.
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Antihydrogen hyperfine splitting measured to 4 ppm, tightening CPT tests and antimatter structure probes
A CERN ALPHA Collaboration study reports a four-parts-per-million measurement of the antihydrogen ground-state hyperfine splitting (a1S/h) using microwave spectroscopy on ~24,000 trapped anti-atoms in a flattened 1 T magnetic trap. By comparing two spin-flip transitions at magnetic minimums in 1.03 T and 1.07 T, the team determines a1S/h = 1,420,404.8 ± 1.1 (stat) ± 5.6 (sys) kHz, consistent with hydrogen and CPT invariance. The result probes the antiproton’s internal structure (Zemach corrections) at ~40 ppm and complements ongoing 1S–2S measurements, with future plans to push precision further (e.g., Sternheim interval, 0.65 T transitions). Achieving this precision relies on improved magnetic-field control, spin-state manipulation, and antihydrogen accumulation, as well as careful handling of magnetic-field drift and lineshape modeling.
CERN Detects Excited Bc*+ Meson at the LHC
ATLAS physicists at CERN observed the excited Bc*+ meson, a heavy-quark bound state (charm quark with a bottom antiquark), produced in high-energy proton-proton collisions at the LHC. The Bc*+ rapidly decays to a Bc+ meson and a photon, which was identified indirectly when the photon converted into an electron–positron pair in the detector. The measured mass difference between Bc*+ and Bc+ is 64.5 ± 1.4 MeV, consistent with theoretical expectations and providing new data to refine models of heavy-quark dynamics and the strong force. Publication is set for Physical Review Letters.
Big G Remains Elusive as a Decade of Gravity Tests Clash with CODATA
After a decade of cross‑Atlantic replication led by NIST, the new measurement of the gravitational constant G disagrees with both the 2013 BIPM result and CODATA’s current value, highlighting that Big G is still the least precisely known fundamental constant and that the true value remains unresolved despite improved methods (including a blinded measurement to reduce bias).
Dirac Fluid Emerges in Graphene, Defying a Core Law of Metals
Scientists observed a Dirac fluid in ultraclean graphene where electrons flow like a nearly frictionless liquid at the Dirac point, causing heat and charge transport to decouple and violating the Wiedemann-Franz law by over 200x, revealing universal quantum behavior and offering a new platform for exploring extreme-physics phenomena.
Researchers Reveal Rich 48-Dimensional Topology Inside Entangled Photons
Researchers at the University of the Witwatersrand and collaborators demonstrated that entangled photons carry a hidden, high-dimensional topology—up to 48 dimensions—with over 17,000 distinct signatures. This topology arises from a single property of light, its orbital angular momentum, enabling a new high-dimensional encoding scheme for quantum information. Because OAM spans many values, the resulting topology can be very rich, and the effect can be observed using standard SPDC lab setups, potentially improving the robustness of future quantum technologies.
Decoding Quantum Chaos with a Single Scramblon
A combined experiment/theory study using solid-state NMR on a powder of adamantane demonstrates that quantum chaos in a many-body system can be captured by a single scramblon mode. By applying scramblon theory to disentangle intrinsic chaotic scrambling from imperfections in time reversal, researchers extract a quantum Lyapunov exponent and a universal decay parameter, supporting a universal, simple description of chaotic dynamics that could bridge tabletop quantum experiments with holographic gravity concepts.
Graphene bilayers reveal a reversible superfluid-to-supersolid transition in excitons
Physicists using two closely spaced graphene layers, a strong magnetic field, and ultracold temperatures observed bilayer excitons transition from a superfluid to an insulating, lattice-like state (interpreted as a supersolid) and then revert back to a superfluid, marking the first reported reversible superfluid-to-supersolid transition in this system in a Nature study led by Cory Dean and colleagues.
Emergent Topology Arises in Quantum-Critical CeRu4Sn6
Researchers at TU Wien report that the quantum material CeRu4Sn6 enters a quantum-critical regime at ultra-low temperatures where electrons lose their particle-like character, yet the system hosts an emergent topological semimetal state. They observed a spontaneous (anomalous) Hall effect without an external magnetic field, linking quantum fluctuations to topology and suggesting that topological properties can arise even when the conventional particle-picture fails. The work also points to a generalized, emergent view of topology and proposes focusing on quantum-critical materials to discover new topological phases.
Mapping Interaction Effects on Quantum Hall Edge States
The article discusses the visualization and analysis of interaction-driven restructuring of quantum Hall edge states in graphene using advanced scanning tunneling microscopy techniques, providing insights into the topological and electronic properties of these states.
Precision Spectroscopy Highlights Discrepancies Between Theory and Experiment
Recent high-precision spectroscopy experiments on helium isotopes reaffirm a significant discrepancy between theoretical calculations and experimental measurements of the ionization energy of the helium-3 and helium-4 triplet states, suggesting potential new physics or unknown interactions affecting only the triplet spectrum.