Physical review letters最新文献

This corrects the article DOI: 10.1103/PhysRevLett.125.102505.

The chromium spinels MgCr_{2}O_{4} and ZnCr_{2}O_{4} are prime examples of the highly frustrated pyrochlore lattice antiferromagnet. Experiment has carefully established that both materials, upon cooling, distort to lower symmetry and order magnetically. We study the nature of this process by a combination of density-functional-theory-based energy mapping and classical Monte Carlo simulations. We first computationally establish precise Heisenberg Hamiltonian parameters for the high temperature cubic and the low temperature tetragonal and orthorhombic structures of both spinels. We then investigate the respective ordering temperatures of high symmetry and low symmetry structures. We carefully compare our results with experimental facts and find that our simulations are remarkably consistent with a type of spin-Peierls mechanism, adapted to three dimensions, where the structural distortion is mediated by a magnetic energy gain due to a lower degree of frustration.

The moiré superlattices attract growing interest for holding exotic physics due to their fascinating properties from electronics to photonics. Much attention has been focused on the localization effect for waves in the flat band regime or the delocalization effect from the strongly dispersive band feature. Here, we study the weakly dispersive band in between the two above scenarios in a one-dimensional synthetic frequency moiré superlattice and observe the wave packet distributions therein toward novel frequency comb generation. Mode spacing in the spectral wave packet is reduced compared to the free spectral range of individual rings due to the mode couplings from the unequal sublattice periods of the synthetic moiré lattice. We unveil that the optimal compact frequency comb generation occurs in the weakly dispersive regime holding simultaneously uniform power distribution and broad frequency spanning in our experiment, benefiting from the interplay between the band flatness and power uniformity of mode distribution. Our results study the fundamental physics of the weakly dispersive moiré band in the synthetic frequency dimension and also show a new way for the future compact frequency comb generation in on-chip devices with small footprint size.

Solid-state defects susceptible of spin manipulation hold great promise for scalable quantum technology. To broaden their utility, operation at room temperature and emission in the telecom wavelength range are desired, eliminating cryogenic requirements and leveraging existing optical fiber infrastructure for the transmission of quantum information. To that end, we report that telecom single-photon emitters (SPEs) in gallium nitride (GaN) exhibit optically detected magnetic resonance (ODMR) at room temperature. The analysis of ODMR as a function of magnetic field orientation enables the determination of the orientation of the spin quantization axis with respect to the GaN crystalline lattice. The optical transitions dynamics are analyzed to gain further insight into the transition rates dominating ODMR. Our findings, coupled with the mature fabrication technology of GaNs, could facilitate the realization of scalable quantum technology.

In this Letter, we report on the experimental generation of high energy (10 GeV), ultrashort (femtosecond-duration), ultrahigh current (∼0.1  MA), petawatt peak power electron beams in a particle accelerator. These extreme beams enable the exploration of a new frontier of high-intensity beam-light and beam-matter interactions broadly relevant across fields ranging from laboratory astrophysics to strong field quantum electrodynamics and ultrafast quantum chemistry. We demonstrate our ability to generate and control the properties of these electron beams by means of a laser-electron beam shaping technique. This experimental demonstration opens the door to on-the-fly customization of extreme beam current profiles for desired experiments and is poised to benefit a broad swath of cross-cutting applications of relativistic electron beams.

Flat-band materials have garnered extensive attention due to their captivating properties associated with strong correlation effects. While flat bands have been discovered in several types of 2D materials, their existence in 1D systems remains elusive. Here, we propose a 1D frustrated lattice, specifically the 1D zigzag lattice, as a platform for hosting flat bands. This lattice can be experimentally realized by growing CuTe chains on Cu(111). The presence of flat bands was confirmed by tight-binding model analysis, first-principles calculations, and angle-resolved photoemission spectroscopy measurements. In addition, we discovered a temperature-driven phase transition at approximately 250 K. Detailed analyses demonstrate that the system has a Tomonaga-Luttinger liquid behavior, accompanied by spin-charge separation effects. Our work unveils new prospects for investigating strongly correlated electron behaviors and topological properties in the 1D limit.

An integral relation is derived from the Fokker-Planck equation which connects the steady-state probability currents with the dynamics of relaxation on short timescales in the limit of small perturbation fields. As a consequence of this integral relation, a general lower bound on the steady-state entropy production is obtained. Two particular ensembles of perturbation fields are then considered, respectively constant gradients and density displacements, and correspondingly two different averaging-based thermodynamic bounds are derived from the integral relation. These provide feasible methods to estimate the steady-state entropy production from relaxation experiments.

We propose a Bayesian inference estimation of in-medium modification of the cluster self-energies from light nuclei multiplicities measured in selected samples of central ^{136,124}Xe+^{124,112}Sn collisions with the INDRA apparatus. The data are interpreted with a relativistic quasiparticle cluster approach in the mean-field approximation without any prior assumption on the thermal parameters of the model. An excellent reproduction is obtained for H and He isotope multiplicities, and compatible posterior distributions are found for the unknown thermal parameters. We conclude that the cluster-σ-meson coupling is temperature dependent, becoming weaker when the temperature increases, in agreement with microscopic quantum statistical calculations. This implies a faster decrease of the light cluster abundances with temperature than previously estimated.

The lowest Landau level of bilayer graphene has an octet of internal degrees of freedom, composed from spin, valley, and orbital two-level systems. Dominance of n=0 orbitals over n=1 orbitals in low energy quantum fluctuations leads to distinct fractional quantum Hall characteristics compared dominance of n=1 over n=0. The competition between n=0 and n=1 orbitals depends sensitively on particle-hole asymmetry in the single-particle Hamiltonian and on Lamb shifts due to exchange interactions with the negative energy sea, which must be accounted for simultaneously in assessing the orbital competition. We identify the circumstances under which n=1, which supports strong even-denominator fractional quantum Hall states with non-Abelian quasiparticles, emerges robustly as the low-energy Landau level.

A fundamental limitation of quantum communication is that a single qubit can carry at most one bit of classical information. For an important class of quantum communication channels, known as entanglement breaking, this limitation holds even if the sender and receiver share entangled particles. But does this mean that, for the purpose of communicating classical messages, a noisy entanglement-breaking qubit channel can be replaced by a noisy bit channel? Here we answer the question in the negative. We introduce a game, similar to the Monty Hall problem in classical statistics, where a sender assists a receiver in finding a valuable item (the "prize") hidden in one of four possible boxes, while avoiding a hazardous item (the "bomb") hidden in one of the remaining three boxes. We show that no classical strategy using a noisy bit channel can ensure that the bomb is avoided, even if the sender and receiver share arbitrary amounts of randomness. In contrast, communication of a qubit through a class of noisy entanglement-breaking channels, which we call quantum not channels, allows the players to deterministically avoid the bomb and to find the prize with a guaranteed nonzero probability. Our findings show that the communication of classical messages through a noisy entanglement-breaking qubit channel assisted by quantum entanglement cannot, in general, be simulated by communication through a noisy bit channel assisted by classical correlations.