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Cluster states are a key resource in quantum technologies, but generation of large-scale 2D cluster states faces several difficulties. Here, the authors show how to generate a 2 × n ladder-like cluster state via sequential emission of time- and frequency multiplexed photonic qubits from a transmon-based device.

Scattering resonances are quantum effects occurring in low-temperature molecular collisions. Here the authors observe resonances for the six-atom ND₃-H₂/HD systems in velocity map imaging experiments explained by high-level theoretical predictions.

2D chiral polaritons are light-matter states with select angular momentum holding technological promise. Here, the authors present the theory of such states, and propose their realisation based on a phenomenon called “apparent circular dichroism”.

Bosonic qubits can be engineered to feature intrinsic protection against certain kinds of errors, which makes quantum error correction across many bosonic qubits possible with less overhead.

Using a virtual reality apparatus in rats that dissociates external landmarks from self-motion cues, the authors describe how the two modes of theta phase coding in the hippocampus during navigation are controlled via distinct computations.

Implementations of quantum walks on ion trap quantum computers have been so far limited to the analogue simulation approach. Here, the authors implement a quantum-circuit-based discrete quantum walk in one-dimensional position space, realizing a Dirac cellular automaton with tunable mass parameter.

Quantum systems make it challenging to determine candidate Hamiltonians from experimental data. An automated protocol is presented and its capabilities to infer the correct Hamiltonian are demonstrated in a nitrogen-vacancy centre set-up.

A logical qubit is a two-dimensional subspace of a higher dimensional system, whose manipulation requires precise control over the whole system. Here the authors demonstrate a control strategy which exploits precise knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system.

Realization of photon-photon interaction is an interesting but challenging goal in photonics and quantum optics. Here the authors use a coherently delayed optomechanical platform with quantum feedback to generate the strong interaction between the single photons propagating in a waveguide.

Recently topological phases have been generalized to amorphous materials, but demonstrations have been limited to non-interacting particles. Cassella et al. show the emergence of chiral amorphous quantum spin liquid in an exactly soluble model by extending the Kitaev honeycomb model to random lattices.

High-mobility graphene can play host to exciton polaritons—hybrid matter–light particles, which can form into a state known as a quantum Hall polariton fluid. Here, the authors show that electron–electron interactions can act to destabilize this state and lead to the formation of a modulated phase.

A deterministic single-photon two-qubit SWAP gate between polarization and spatial-momentum is demonstrated on a silicon chip. A two-qubit swapping process fidelity of 94.9% is obtained. The coherence preservation of the SWAP gate process is verified by two-photon interference.

Coherent photon sources are essential for quantum technologies like sensing and computing. This work proposes a superconducting circuit design enabling on-chip, tunable photon emission via an external control, offering stable and precise control without disturbing the source dynamics.

Wave breaking mechanisms relevant for modelling of ocean-atmosphere interaction and rogue waves, remain computationally challenging. The authors propose a machine learning framework for prediction of breaking and its effects on wave evolution that can be applied for forecasting of real world sea states.

Organic semiconductors employed in light-emitting diodes (OLEDs) allow for magnetic resonance studies that explore light-matter interactions in the ultrastrong-drive regime, where the Rabi frequency exceeds the Larmor frequency. The authors report the formation of Floquet spin states in OLEDs.

The ability to transfer quantum information from a memory to a flying qubit is important for building quantum networks. The very fast release of a multiphoton state in a microwave cavity memory into propagating modes is demonstrated.

Quantum communications operate with shared multipartite entangled states, and this has to be certified in a setting where not all parties are trusted in the same way. Here the authors propose a method to certify multipartite entanglement in asymmetric scenarios and demonstrate it in an optical experiment.

Untrustworthy sources or detectors mean that quantum entanglement cannot always be ensured, but quantum steering inequalities can verify its presence. Using a highly efficient system, Smithet al. are able to close the detection loophole and clearly demonstrate steering between two parties.

Scalable methods employing a random unitary chip and a quantum walk chip are developed to experimentally verify correct operation for large-scale boson sampling. Experimental analysis reveals that the resulting statistics of the output of a linear interferometer fed by indistinguishable single-photon states exhibits true non-classical characteristics.

Characterization of quantum chaotic systems involves a detailed understanding of their spectral properties. This work analyses such features in ultracold driven one-dimensional atomic gases, with emphasis on emerging universal scaling in early time deviations of the spectral form factor from random matrix theory predictions, outlining a potential experimental observational protocol.

The role of the human claustrum during slow wave sleep is unknown. Here the authors characterize the spiking activity of claustrum neurons in humans and demonstrate that claustrum neurons track slow waves during NREM sleep.

A noise-resilient protocol implemented in a cavity resonator coupled to a qubit demonstrates that large nonlinear couplings are not a necessary requirement for the fast universal control and state preparation of engineered quantum systems.

Is it possible to deduce the number of dimensions of a completely unknown system only from the results of measurements performed on it? So-called dimension witnesses allow such an estimation, and are now experimentally demonstrated using pairs of entangled photons.

Waves are ubiquitous in nature and occur across various scales and settings. In this Primer, Jafarzadeh et al. discuss techniques for preprocessing and analysing waves, including information on choosing the appropriate methods based on wave properties, and present worked examples using synthetic datasets.

Magnetic skyrmions are topological spin textures, most notably occurring in magnetic materials. So far, the skyrmions that have been reported correspond to topological textures of magnetic dipole moments. Zhang et al show theoretically that quantum effects can lead to a distinct type of skyrmion that combines dipolar and quadrupolar moments, proposing a variety of materials, including magnets and quantum paramagnets, where such textures can be stabilized.

Simulating ultrafast quantum dissipation in molecular excited states is a strongly demanding computational task. Here, the authors combine tensor network simulation, entanglement renormalisation and machine learning to simulate linear vibronic models, and test the method by analysing singlet fission dynamics.

A lack of non-destructive measurements and difficulty in tuning direct coupling between motional modes limits quantum information processing with trapped ions. Both features have now been achieved in an ion crystal using oscillating electric fields.

Measurement-based quantum computing is one of the most promising approaches for photon-based universal quantum computation. Here, the authors realise a universal encoder of four-photon graph states on a silicon chip, and use Bayesian inference methods to characterise the error sources.

A quantum simulation of a (2 + 1)-dimensional lattice gauge theory is carried out on a quantum computer working with neutral atoms trapped by optical tweezers in a Kagome geometry.

Repeated error correction creates a logical qubit encoded in the hybrid state of a superconducting circuit and a bosonic cavity, which is shown to be fully controllable under a universal single-qubit gate set.

Some materials can display magnetic order despite having spin-singlet ground state on individual magnetic sites. This arises due to exchange interactions mixing excited crystal electric field states. Here, Gao et al study and example of such a system, Ni₂Mo₃O₈, and find that crystal electric field states in both the paramagnetic and antiferromagnetic states exhibit dispersive excitations.

The quantum marginal problem interrogates the existence of a global pure quantum state with some given marginals. Here, the authors reformulate it as an optimisation problem, and specifically as the existence of a two-party separable state with additional semidefinite constraints.

Researchers demonstrate a reconfigurable integrated quantum photonic circuit. The device comprises a two-qubit entangling gate, several Hadamard-like gates and eight variable phase shifters. The set-up is used to generate entangled states, violate a Bell-type inequality with a continuum of partially entangled states and demonstrate the generation of arbitrary one-qubit mixed states.

To realize long-distance quantum communication it is required to have individually addressable quantum memories with programmable access to many cells. Here the authors report DLCZ-type quantum memories with 225 individually accessible memory cells in a macroscopic atomic ensemble

Recent developments that reduce the computational cost and scaling of wavefunction-based quantum-chemical techniques open the way to the successful application of such techniques to a variety of real-world solids.

Imaging and optogenetics in mice provide insight into the interplay between the primary motor cortex and the motor thalamus during learning, showing that thalamic inputs have a key role in the execution of learned movements.

Long-range Ising interactions present in one-dimensional spin chains can induce a confining potential between pairs of domain walls, slowing down the thermalization of the system. This has now been observed in a trapped-ion quantum simulator.

Neural mechanisms underlying thalamic contributions to evoked potentials by brain stimulation, which has been widely used for therapeutic interventions, are not fully understood. In this translational study the authors show that the thalamus plays a critical role in shaping its neural responses across species and across stimulation modalities.