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# Top 50 Physics Articles

We are pleased to share with you the 50 most read Nature Communications articles* in physics published in 2019. Featuring authors from around the world, these papers highlight valuable research from an international community.

Browse all Top 50 subject area collections here.

*Based on data from Google Analytics, covering January-December 2019 (data has been normalised to account for articles published later in the year)

# 1-25

### Perfect secrecy cryptography via mixing of chaotic waves in irreversible time-varying silicon chips

Protecting confidential data through fast and scalable cryptographic techniques remains a challenge. Here, the authors demonstrate a cryptographic system via correlated mixing of chaotic waves in irreversible time-varying silicon chips with key distributions in classical optical channels.

Article | Open Access | |

### The Eighty Five Percent Rule for optimal learning

Is there an optimum difficulty level for training? In this paper, the authors show that for the widely-used class of stochastic gradient-descent based learning algorithms, learning is fastest when the accuracy during training is 85%.

Article | Open Access | |

### Estimating the success of re-identifications in incomplete datasets using generative models

Anonymization has been the main means of addressing privacy concerns in sharing medical and socio-demographic data. Here, the authors estimate the likelihood that a specific person can be re-identified in heavily incomplete datasets, casting doubt on the adequacy of current anonymization practices.

Article | Open Access | |

### A critique of pure learning and what artificial neural networks can learn from animal brains

Recent gains in artificial neural networks rely heavily on large amounts of training data. Here, the author suggests that for AI to learn from animal brains, it is important to consider that animal behaviour results from brain connectivity specified in the genome through evolution, and not due to unique learning algorithms.

Perspective | Open Access | |

### Automated acquisition of explainable knowledge from unannotated histopathology images

Technologies for acquiring explainable features from medical images need further development. Here, the authors report a deep learning based automated acquisition of explainable features from pathology images, and show a higher accuracy of their method as compared to pathologist based diagnosis of prostate cancer recurrence.

Article | Open Access | |

### Benchmarking an 11-qubit quantum computer

The growing complexity of quantum computing devices makes presents challenges for benchmarking their performance as previous, exhaustive approaches become infeasible. Here the authors characterise the quality of their 11-qubit device by successfully computing two quantum algorithms.

Article | Open Access | |

### Skyrmion phase and competing magnetic orders on a breathing kagomé lattice

Understanding and controlling the skyrmion lattice (SkL) phase facilitates its versatile applications. Here the direct observation of a SkL phase with large topological Hall effect in centrosymmetric Gd3Ru4Al12 is reported, which is stabilized by thermal fluctuations and magnetic field without Dzyaloshinskii-Moriya interactions.

Article | Open Access | |

### A first-principle mechanism for particulate aggregation and self-assembly in stratified fluids

Aggregation of matter, common in stratified fluid systems, is essential to the carbon cycle and ocean ecology. Although the current understanding of aggregation involves only collision and adhesion, here Camassa et al. reveal a self-assembly phenomenon arising solely from diffusion-induced flows.

Article | Open Access | |

### The METLIN small molecule dataset for machine learning-based retention time prediction

The use of machine learning for identifying small molecules through their retention time’s predictions has been challenging so far. Here the authors combine a large database of liquid chromatography retention time with a deep learning approach to enable accurate metabolites’s identification.

Article | Open Access | |

### Single-molecule detection on a portable 3D-printed microscope

Single-molecule in vitro assays require dedicated confocal microscopes equipped with fluorescence correlation spectroscopy (FCS) modules. Here the authors present a compact, cheap and open-source 3D-printed confocal microscope for single photon counting and FCS measurements, and use it to detect α-synuclein aggregation.

Article | Open Access | |

### Bell’s theorem for temporal order

Time has a fundamentally different character in quantum mechanics and in general relativity. Here, the authors consider a thought experiment where a massive body in a spatial superposition leads to entanglement of temporal orders between time-like events, resulting in a violation of a Bell-type inequality.

Article | Open Access | |

### RNA secondary structure prediction using an ensemble of two-dimensional deep neural networks and transfer learning

The limited availability of high-resolution 3D RNA structures for model training limits RNA secondary structure prediction. Here, the authors overcome this challenge by pre-training a DNN on a large set of predicted RNA structures and using transfer learning with high-resolution structures.

Article | Open Access | |

### Enhanced control of self-doping in halide perovskites for improved thermoelectric performance

Metal halide perovskites show excellent optoelectronic properties but the understanding on their thermoelectric properties has been limited. Here Liu et al. develop a strategy for controlled doping and achieve a high figure of merit ZT value of 0.14 via careful composition engineering.

Article | Open Access | |

### Brain age prediction using deep learning uncovers associated sequence variants

Machine learning algorithms can be trained to estimate age from brain structural MRI. Here, the authors introduce a new deep-learning-based age prediction approach, and then carry out a GWAS of the difference between predicted and chronological age, revealing two associated variants.

Article | Open Access | |

### The valley Nernst effect in WSe2

Atomically thin transition metal dichalcogenides possess a valley degree of freedom, which could enrich the physics underpinning the conventional Nernst effect observed in traditional solids. Here, the authors report experimental evidence of the valley Nernst effect in WSe2 at room temperature.

Article | Open Access | |

### Flexible and durable wood-based triboelectric nanogenerators for self-powered sensing in athletic big data analytics

Intelligent sensing technologies gain interest for the internet of things and applications that require collection and analysis of big data. Here the authors report a flexible and durable wood-based triboelectric nanogenerator for self-powered sensing in athletic big data analytics.

Article | Open Access | |

### Massive computational acceleration by using neural networks to emulate mechanism-based biological models

Mechanistic models provide valuable insights, but large-scale simulations are computationally expensive. Here, the authors show that it is possible to explore the dynamics of a mechanistic model over a large set of parameters by training an artificial neural network on a smaller set of simulations.

Article | Open Access | |

### Complementary vibrational spectroscopy

Generally infrared and Raman spectroscopic methods are needed to study the symmetric and asymmetric molecular vibrational modes. Here the authors demonstrate complementary vibrational spectroscopy to organic molecules by simultaneously measuring their symmetric and anti-symmetric vibrations with one setup.

Article | Open Access | |

### Characterizing large-scale quantum computers via cycle benchmarking

Checking the quality of operations of quantum computers in a reliable and scalable way is still an open challenge. Here, the authors show how to characterise multi-qubit operations in a way that scales favourably with the system’s size, and demonstrate it on a 10-qubit ion-trap device.

Article | Open Access | |

### Over 16% efficiency organic photovoltaic cells enabled by a chlorinated acceptor with increased open-circuit voltages

Halogenation has proved an effective strategy to improve the power conversion efficiencies of organic solar cells but it usually leads to lower open-circuit voltages. Here, Cui et al. unexpectedly obtain higher open-circuit voltages and achieve a record high PCE of 16.5% by chlorination.

Article | Open Access | |

### Room-temperature quantum interference in single perovskite quantum dot junctions

Quantum interference effects remain elusive in halide perovskite materials. Here Zheng et al. reveal the atomic origin of the conductance features in the single perovskite quantum dot junctions, and present direct evidence of the room-temperature quantum interference effects.

Article | Open Access | |

### Triplet–triplet upconversion enhanced by spin–orbit coupling in organic light-emitting diodes

Though triplet-triplet upconversion is a promising strategy for designing new deep blue-emitting organic materials, maximizing the efficiency of this process remains difficult. Here, the authors report the upconversion efficiency in anthracene derivatives based on a spin-orbit coupling mechanism.

Article | Open Access | |

### Strong optical response and light emission from a monolayer molecular crystal

The optical response of inorganic two-dimensional semiconductors is dominated by Wannier-Mott excitons, but molecular systems can host localised Frenkel excitons. Here, the authors report strong optical response in a class of monolayer molecular J-aggregates due to the coherent Coulomb interaction between localised Frenkel excitons.

Article | Open Access | |

### Automated optimized parameters for T-distributed stochastic neighbor embedding improve visualization and analysis of large datasets

Visualisation tools that use dimensionality reduction, such as t-SNE, provide poor visualisation on large data sets of millions of observations. Here the authors present opt-SNE, that automatically finds data set-tailored parameters for t-SNE to optimise visualisation and improve analysis.

Article | Open Access | |

### Single-spin qubits in isotopically enriched silicon at low magnetic field

One of the main sources of decoherence in silicon electron spin qubits is their interaction with nearby fluctuating nuclear spins. Zhao et al. present a device made from enriched silicon to reduce the nuclear spin density and find its performance is still limited by fluctuations of residual spins.

Article | Open Access | |

# 26-50

### Millimetre-long transport of photogenerated carriers in topological insulators

Exciton condensation may emerge at room temperature in topological materials with strong Coulomb interactions and vanishing electron effective mass. Here, Hou et al. report the formation of excitons in Bi2-xSbxSe3 nanoribbons, which can transport over hundreds of micrometres before recombination up to 40 K, further implying exciton condensation.

Article | Open Access | |

### Compact and ultra-efficient broadband plasmonic terahertz field detector

Most efficient terahertz detection schemes rely on complex free space optics and require high-power lasers. Here, the authors report an integrated plasmonic terahertz detector on a silicon photonics platform, with 2.5 THz bandwidth and a 65 dB dynamical range operating at an optical power of only 63 nW.

Article | Open Access | |

### Slow recombination of spontaneously dissociated organic fluorophore excitons

Though highly emissive charge-transfer type molecules in a host matrix is an attractive material for organic opto-electronics, concentration quenching limits photoluminescence quantum yield. Here, the authors report concentration quenching in fluorophores based on spontaneous exciton dissociation.

Article | Open Access | |

### DNA origami cryptography for secure communication

Biomolecular cyptography that exploits specific interactions could be used for data encryption. Here the authors use the folding of M13 DNA to encrypt information for secure communication.

Article | Open Access | |

### Carrier multiplication in van der Waals layered transition metal dichalcogenides

During carrier multiplication, high-energy free carriers in a given material relax by generation of additional electron-hole pairs. Here, the authors report evidence of carrier multiplication in multilayer MoTe2 and WSe2 films with up to 99% conversation efficiency.

Article | Open Access | |

### Formation of optical supramolecular structures in a fibre laser by tailoring long-range soliton interactions

Optical solitons have been studied in a variety of systems for their unique properties. Here, the authors report on optically observed solitonic supramolecules, made up of large-scale structures of many solitons interacting within a fiber cavity, and study their fundamental characteristics.

Article | Open Access | |

### Creation and annihilation of topological meron pairs in in-plane magnetized films

A meron is one half of a skyrmion but whether a single meron pair can be created and stabilized remains a challenging question. Here, Gao et al. develop a method to create and stabilize individual pairs of merons in a continuous Py film by local vortex imprinting from Co disks.

Article | Open Access | |

### Video-rate multi-color structured illumination microscopy with simultaneous real-time reconstruction

Sequential acquisition and image reconstruction in super-resolved structured illumination microscopy (SR-SIM) is time-consuming. Here the authors optimise both acquisition and reconstruction software to achieve multicolour SR-SIM at video frame-rates with reconstructed images displaying with only milliseconds delay during the experiment.

Article | Open Access | |

### Optical nanomanipulation on solid substrates via optothermally-gated photon nudging

Particle manipulation is still challenging even with the many tools available, especially manipulating particles on a surface. Here, the authors report a technique for nanomanipulation of various objects on solid substrates by modulating particle-substrate interactions through laser-induced opto-thermal dynamics.

Article | Open Access | |

### Molecular movie of ultrafast coherent rotational dynamics of OCS

Molecular movies provide crucial information of fundamental processes like energy and charge transfer, bond breaking etc. Here the authors show the time evolution of the rotational wave packet called the molecular movie of OCS molecules by Coulomb explosion imaging.

Article | Open Access | |

### The European Space Agency’s Comet Interceptor lies in wait

The European Space Agency (ESA) recently selected Comet Interceptor as its first ‘fast’ (F-class) mission. It will be developed rapidly to share a launch with another mission and is unique, as it will wait in space for a yet-to-be-discovered comet.

Comment | Open Access | |

### Probing the edge-related properties of atomically thin MoS2 at nanoscale

Probing inevitable defects in two- dimensional materials is challenging. Here, the authors tackle this issue by using tip-enhanced Raman spectroscopy (TERS) to obtain distinctly different Raman features of edge defects in atomically thin MoS2, and further probe their unique electronic properties as well as identify the armchair and zigzag edges.

Article | Open Access | |

### A rotary plasmonic nanoclock

Current DNA-assembled nanophotonic devices can only reconfigure among random or few defined states. Here, the authors demonstrate a DNA-assembled rotary plasmonic nanoclock in which a rotor gold nanorod carries out directional and reversible 360° rotation transitioning among 16 well-defined configurations.

Article | Open Access | |

### Programmable and robust static topological solitons in mechanical metamaterials

Mechanical solitons are notoriously difficult to control. Here, the authors report a theoretical framework for programming static periodic topological solitons into a metamaterial, and demonstrate its implementation in real metamaterials computationally and experimentally.

Article | Open Access | |

### Enhanced light-matter interaction in an atomically thin semiconductor coupled with dielectric nano-antennas

Dielectric nano-antennas may be used as a platform for boosting light-matter coupling in 2D semiconductors. Here, the authors demonstrate the coupling of atomically thin WSe \$\${}_{2}\$\$ ${}_{2}$ with low-loss, high-refractive-index GaP nano-antennas and observe a 10000-fold WSe \$\${}_{2}\$\$ ${}_{2}$ photoluminescence enhancement.

Article | Open Access | |

### Towards a fully automated algorithm driven platform for biosystems design

Existing efforts have been focused on one of the elements in the automation of the design, build, test, and learn (DBTL) cycle for biosystems design. Here, the authors integrate a robotic system with machine learning algorithms to fully automate the DBTL cycle and apply it in optimizing the lycopene biosynthetic pathway.

Article | Open Access | |

### Scale-invariant magnetic textures in the strongly correlated oxide NdNiO3

The many strongly interacting degrees of freedom in transition metal oxides make it difficult to capture and describe the nature of their metal-insulator transitions. Li et al. show that a resonant magnetic X-ray nanoprobe gives access to local critical behavior that is difficult to detect otherwise.

Article | Open Access | |

### A vertical silicon-graphene-germanium transistor

Graphene-base transistors were originally proposed for high-frequency applications, but the height of the emitter potential barrier limits the transistor performance towards the THz range. Here, the authors fabricate a vertical silicon-graphene-germanium transistor with a Schottky emitter enabling a transition from MHz to GHz operation.

Article | Open Access | |

### Scale-free networks are rare

Real-world networks are often said to be ”scale free”, meaning their degree distribution follows a power law. Broido and Clauset perform statistical tests of this claim using a large and diverse corpus of real-world networks, showing that scale-free structure is far from universal.

Article | Open Access | |

### Game theoretical inference of human behavior in social networks

Based on a strategic network formation model, the authors develop game-theoretical and statistical methods to infer individuals’ incentives in complex social networks, and validate their findings in real-world, historical data sets.

Article | Open Access | |

### Task complexity interacts with state-space uncertainty in the arbitration between model-based and model-free learning

The brain dynamically arbitrates between two model-based and model-free reinforcement learning (RL). Here, the authors show that participants tended to increase model-based control in response to increasing task complexity, but resorted to model-free when both uncertainty and task complexity were high.

Article | Open Access | |

### High-efficiency and integrable DNA arithmetic and logic system based on strand displacement synthesis

Current DNA computational systems are constrained by integration efficiency, device structures and limited functions. Here the authors design a DNA arithmetic logic unit that uses polymerase-mediated strand displacement.

Article | Open Access | |

### Resonant optical Stark effect in monolayer WS2

Many-body interactions have important consequences for the optoelectronic properties of 2D materials. Here, the authors report on how many-body interactions affect the behavior of the valley-selective optical Stark effect for excitation near the A-exciton resonance in monolayer WS2.

Article | Open Access | |

### Quantum nanophotonics with group IV defects in diamond

Diamond colour centres have applications in quantum sensing, quantum communication and other important technologies. Bradac et al. survey the progress made in using group IV defect centres, which are anticipated to have practical advantages over the more commonly-used nitrogen vacancy centres.

Perspective | Open Access | |

### Direct observation of imploded core heating via fast electrons with super-penetration scheme

Fast ignition is an interesting scheme for nuclear fusion reaction. Here the authors show electron generation using intense short laser pulses and energy transport by coupling the laser energy to the imploded plasma core as in the ICF conditions.

Article | Open Access | |