Volume 20 Issue 5, May 2024

Thousands of Iranians study at German universities every year, but many struggle with the German academic system. Here, we offer some advice.

Inertial confinement represents one of two viable approaches for producing energy from the fusion of hydrogen isotopes. Scientists have now achieved a record yield of fusion energy when directly irradiating targets with only 28 kilojoules of laser energy.

The integration of theory and experiment makes possible tracking the slow evolution of a photodoped Mott insulator to a distinct non-equilibrium metallic phase under the influence of electron-lattice coupling.

Excitation of magnons — quanta of spin-waves — in an antiferromagnet can be used for high-speed data processing. The addition and subtraction of two such modes opens up possibilities for magnon-based information transfer in the terahertz spectral region.

Even by shining classical light on a single opening, one can perform a double-slit experiment and discover a surprising variety of quantum mechanical multi-photon correlations — thanks to surface plasmon polaritons and photon-number-resolving detectors.

Interacting emitters are the fundamental building blocks of quantum optics and quantum information devices. Pairs of organic molecules embedded in a crystal can become permanently strongly interacting when they are pumped with intense laser light.

A single light-emitting dye molecule precisely placed within the tiny gap of a metal nanodimer boosts light–matter coupling — a step closer to the development of quantum devices operating at room temperature.

The concept of temporal mode-locking has been leveraged to study the interplay between laser mode-locking and photonic lattices that exhibit non-Hermitian topological phenomena. The results suggest new opportunities to study nonlinear and non-Hermitian topological physics as well as potential applications to sensing, optical computing and frequency-comb design.

Cold and ultracold molecules have emerged in the past two decades as a central topic in quantum gas studies. This Review charts the recent advances in cooling and quantum state control techniques that are shaping this evolving field.

Molecular ions and hybrid platforms that integrate cold trapped ions and neutral particles offer opportunities for many quantum technologies. This Review surveys recent methodological advances and highlights in the study of cold molecular ions.

Ultracold molecules and ion–neutral systems offer unique access to chemistry in a coherent quantum regime. This Review charts the progress of studies of quantum chemistry in such platforms, highlighting the synergy between theory and experiments.

The study of quantum systems in a programmable and controllable fashion is one of the aims of both quantum simulation and computing. This Review covers the prospects and opportunities that ultracold molecules offer in these fields.

Ultracold atoms are a well-established platform for quantum sensing and metrology. This Review discusses the enhanced sensing capabilities that molecules offer for a range of phenomena, including symmetry-violating forces and dark matter detection.

Hydro-equivalent scaling of recent direct-drive inertial confinement fusion implosions shows that a burning plasma can be achieved with a higher laser energy.

Inertial confinement fusion experiments in a direct-drive configuration report more energy produced in deuterium–tritium fusion reactions than the amount of energy in the central part of the plasma created by laser irradiation of the fuel capsule.

Attosecond interferometry measurements of photoionization delays in planar carbon-based molecules can provide information on the dimension and shape of the two-dimensional hole generated in the process.

Photon-mediated entanglement in atomic ensembles coupled to cavities enables the engineering of quantum states with a graph-like entanglement structure. This offers potential advantages in quantum computation and metrology.

Topologically protected hinge modes could be important for developing quantum devices, but electronic transport through those states has not been demonstrated. Now quantum transport has been shown in gapless topological hinge states.

Spin polarons, bound states of a doped carrier and a spin flip excitation, are observed in a transition metal moiré bilayer.

Inducing coherent interactions between distinct magnon modes—collective excitations of magnetic order—has been challenging. A canted antiferromagnet has demonstrated coherent magnon upconversion induced by terahertz laser pulses.

Understanding the mechanism by which magnons—the quanta of spin waves—propagate is important for developing practical devices. Now it is shown that long-range dipole–dipole interactions mediate the propagation in a van der Waals antiferromagnet.

Magnons—quanta of spin waves—have potential applications in signal processing technology. But it is challenging to obtain coupling between different magnons. Now a study achieves this by demonstrating nonlinear magnon mixing in an antiferromagnet.

During a photoinduced phase transition, electronic rearrangements are usually faster than lattice ones. Time-resolved measurements now show that the insulator-to-metal transition in a thin-film Mott insulator is preceded by lattice reconfiguration.

The standard current–phase relation in tunnel Josephson junctions involves a single sinusoidal term, but real junctions are more complicated. The effects of higher Josephson harmonics have now been identified in superconducting qubit devices.

The existence of Bragg glasses—featuring nearly perfect crystalline order and glassy features—has yet to be experimentally confirmed for disordered charge-density-wave systems. A machine-learning-based experimental study now provides evidence for a Bragg glass phase in the charge density waves of Pd_xErTe₃.

Most applications of surface plasmons are based on their near-field properties. These properties are now shown to be governed by nonclassical scattering between multiparticle plasmonic subsystems.

Laser-induced tuning of pairs of lifetime-limited organic emitters allows the controlled creation of superradiant and subradiant entangled states.

Although dissipation is often detrimental to the observation of topological effects, a photonic molecule driven at several incommensurate frequencies is shown to be a candidate system for quantized topological transport in synthetic dimensions.

Mode locking, which is a common technique to produce short laser pulses, is demonstrated in a topological laser.

Combining multiparticle levitation with cavity control enables cavity-mediated interaction between levitated nanoparticles, whose strength can be tailored via optical detuning and position of the two particles.

Cluster states made from multiple photons with a special entanglement structure are a useful resource for quantum technologies. Two-dimensional cluster states of microwave photons have now been deterministically generated using a superconducting circuit.

A transducer that generates microwave–optical photon pairs is demonstrated. This could provide an interface between optical communication networks and superconducting quantum devices that operate at microwave frequencies.

UNESCO has now formally adopted World Metrology Day as a UNESCO International Day to be observed on 20 May each year — the theme of 2024 is sustainability. Shanay Rab and Richard Brown take a look at its origin.