Tyler O'Neal, Staff Editor ACADEMIA

Chinese scientists observe large-scale, ordered, tunable Majorana-zero-mode lattice

In a study, a joint research team led by Prof. GAO Hongjun from the Institute of Physics of the Chinese Academy of Sciences (CAS) has reported observation of a large-scale, ordered and tunable Majorana-zero-mode (MZM) lattice in the iron-based superconductor LiFeAs, providing a new pathway towards future topological quantum super computation. Fig. 1. Characterization of biaxial CDW region. (Image by Institute of Physics)

MZMs are zero-energy bound states confined in the topological defects of crystals, such as line defects and magnetic field-induced vortices. They are characterized by scanning tunneling microscopy/spectroscopy (STM/S) as zero-bias conductance peaks. They obey non-Abelian statistics and are considered building blocks for future topological quantum computation. 

MZMs have been observed in several topologically nontrivial iron-based superconductors, such as Fe (Te0.55Se0.45), (Li0.84Fe0.16)OHFeSe, and CaKFe4As4. However, these materials suffer from issues with alloying-induced disorder, uncontrollable and disordered vortex lattices, and the low yield of topological vortices, all of which hinder their further study and application. 

In this study, the researchers observed the formation of an ordered and tunable MZM lattice in the naturally strained superconductor LiFeAs. Using STM/S equipped with magnetic fields, the researchers found that local strain naturally exists in LiFeAs. Biaxial charge density wave (CDW) stripes along the Fe-Fe and As-As directions are produced by the strain, with wavevectors of λ1~2.7 nm and λ2~24.3 nm. The CDW with wavevector λ2 shows strong modulation of the superconductivity of LiFeAs.  Fig. 2. MZM in vortices. (Image by Institute of Physics)

Under a magnetic field perpendicular to the sample surface, the vortices emerge and are forced to align exclusively along with the As-As CDW stripes, forming an ordered lattice. The reduced crystal symmetry leads to a drastic change in the topological band structures at the Fermi level, thus transforming the vortices into topological ones hosting MZMs and forming an ordered MZM lattice. Moreover, the MZM lattice density and geometry are tunable by an external magnetic field. The MZMs start to couple with each other under high magnetic fields. 

This observation of a large-scale, ordered and tunable MZM lattice in LiFeAs expands the MZM family found in iron-based superconductors, thus providing a promising platform for manipulating and braiding MZMs in the future, according to the researchers. 

These findings may shed light on the study of topological quantum super computation using iron-based superconductors. 

Fig. 3. Majorana mechanism in LiFeAs. (Image by Institute of Physics)

Fig. 4. Tuning the MZM lattice with magnetic field. (Image by Institute of Physics)

QET Labs' breakthrough paves way for photonic sensing at the quantum limit

Tyler O'Neal, Staff Editor ACADEMIA

A Bristol-led team of physicists has found a way to operate mass manufacturable photonic sensors at the quantum limit. This breakthrough paves the way for practical applications such as monitoring greenhouse gases and cancer detection.  Photonic chip with a microring resonator nanofabricated in a commercial foundry. Photo credit: Joel Tasker, QET Labs

Sensors are a constant feature of our everyday lives. Although they often go unperceived, sensors provide critical information essential to modern healthcare, security, and environmental monitoring. Modern cars alone contain over 100 sensors and this number will only increase. 

Quantum sensing is poised to revolutionize today's sensors, significantly boosting the performance they can achieve. More precise, faster, and reliable measurements of physical quantities can have a transformative effect on every area of science and technology, including our daily lives. 

However, the majority of quantum sensing schemes rely on special entangled or squeezed states of light or matter that are hard to generate and detect. This is a major obstacle to harnessing the full power of quantum-limited sensors and deploying them in real-world scenarios. 

In a paper published today, a team of physicists at the Universities of Bristol, Bath, and Warwick have shown it is possible to perform high precision measurements of important physical properties without the need for sophisticated quantum states of light and detection schemes.  

The key to this breakthrough is the use of ring resonators – tiny racetrack structures that guide light in a loop and maximize its interaction with the sample under study. Importantly, ring resonators can be mass-manufactured using the same processes as the chips in our computers and smartphones. 

Alex Belsley, Quantum Engineering Technology Labs (QET Labs) Ph.D. student and lead author of the work, said: “We are one step closer to all integrated photonic sensors operating at the limits of detection imposed by quantum mechanics.” 

Employing this technology to sense absorption or refractive index changes can be used to identify and characterize a wide range of materials and biochemical samples, with topical applications from monitoring greenhouse gases to cancer detection.  

Associate Professor Jonathan Matthews, co-Director of QET Labs and co-author of the work, stated: “We are really excited by the opportunities this result enables: we now know how to use mass manufacturable processes to engineer chip-scale photonic sensors that operate at the quantum limit.”

UK's leading university launches Future of Work Research Centre

Tyler O'Neal, Staff Editor ACADEMIA

How are artificial intelligence technologies transforming jobs and skills? How does hybrid working affect productivity, teamwork, and value creation? These are some of the critical questions explored by the University of Surrey’s new Future of Work Research Centre launched future of work digital business media df14e

The new Research Centre will focus on people management and job quality in a rapidly changing working environment characterized by rapid technological advancements, economic developments, and societal value changes. These changes have transformed the nature and organization of work, as well as conditions of employment.  eco

Professor Ying Zhou, Director of the Future of Work Research Centre at the University of Surrey, said: 

“With so much uncertainty in our work environment, we’ll be looking at the critical questions facing the future workplace – from analysis of job quality and digital technologies through to the hopes and perils of hybrid working. 

“Artificial intelligence, machine learning, and robotics technologies are changing the nature of jobs, with massive implications for training, skills, and careers. Our new Future of Work Research Centre will draw on world-leading expertise across the University of Surrey, covering artificial intelligence, digital technology, and human resource management, as well as working alongside industry and policy partners. Across our work, we’ll be looking to offer advice on how fairness and justice can be secured in an increasingly diverse workforce.” 

Furthermore, the Research Centre is being established just as the UK Government launches its Future of Work Review headed by MP Matt Warman. 

The launch event will feature Professor Glenn Parry, Head of the Department of Digital Economy, Entrepreneurship and Innovation, Professor Francis Green, Professor of Work and Education Economics at UCL Institute of Education, and Jonny Gifford, Senior Advisor for Organisational Behaviour at the Chartered Institute of Personnel and Development. 

More details on the Future of Work Research Centre can be found here.