My science failures: How to err wisely

Science stories are equal to success stories. Right? Wrong. In thinking of scientists as successful people, we often assume that their career paths are straightforward, meticulously planned, and yield positive outcomes. However, things don’t always go as planned. Behind every small success, there’s probably a string of failures — work that did not make it to the curriculum vitae, rejected papers, turned-down applications, declined grants, unsuccessful job interviews, and many closed doors.

Science blooms in these failures as much as it does in the glory of accepted manuscripts, grants, awards, and patents. In this blog series “My Science Failures” we will hear some straight-from-the-heart stories of these secret milestones in the lives of scientists — and learn how they turned these events on their head (or did not).

Vijay Soni, an instructor at Weill Cornell Medicine, New York, says the actual reason why science is so successful is these failures.

Vijay Soni

In science, we fail more often and at a rate higher than in other vocations. Hypotheses go wrong, experiments do not deliver the expected outcomes. There are contaminations, misleadingly simplistic or representative models, false-positive results, experiments without controls, rejections of manuscripts, and failed projects. The actual reason, why science is so successful, is all these failures. It is, therefore, imperative to learn the real value of mistakes.

Failures are a sign that you are inventing,” says Elon Musk. Curiosity guides us to learn better and faster. We have been taught to attach connotations to words and are accustomed to believing that success is positive, and failures are negative. However, learnings are never black and white – they are a full rainbow. Each colour is an experience that must be enjoyed, lived, and felt.

Scientists hardly speak of false starts. There is nothing glamorous about dead and failed stories. And so there is a big chunk of knowledge that goes unreported or unpublished.

How do scientists cope with recurrent failures and grow? In my own research journey, many times I wish I knew about earlier false starts so that it didn’t have to go down an already failed path. I did not find any resource where scientists shared their wisdom from failures. Therefore, I started FailWise to offer learnings, information, opinion, and guidance around such failures. The inspiration came from Brandon Mull’s words: “Smart people learn from their mistakes, but the real sharp ones learn from the mistakes of others.”

Every scientist has a personal relationship with failures, and evolves uniquely. I have too. As a biology undergraduate, I learnt a big lesson early on when my lecturer published under his name all data from a research project I was working on to get a grant. Similarly, a lab mate presented my data without my consent or acknowledgment to get a postdoc position. Lesson I learnt: don’t disclose all your data and research to anyone. Never circulate your lab reports or critical data even among close friends.

There are more things that I learnt as a researcher:

  1. I studied undergraduate in a Hindi medium. I always felt it would be a problem when I go for higher studies. But I was wrong. Language is not a barrier in science but lack of knowledge is. I never stopped reading books and research articles. If you do not read background literature, maintain notes or connect the dots to frame your questions, you will likely fail. Learn to ask better questions, you will automatically be guided towards better answers.
  2. Once I was told that I would not have been hired if I was not from a certain lab (my master’s and undergraduate studies were from a very small state university in India). It was discouraging. But I reminded myself that people who follow their path passionately and honestly make great scientists and labs, and they may not necessarily be working in a world-class institute. No matter what your background, chase your dreams with perseverance.
  3. After Masters, I was working as a project assistant at a renowned institute in India. I was treated like a labourer there — never allowed to ask any question, asked to help in my principal investigator’s household work. He used foul language, forced me to work at least 12 hours every day, even on weekends. I tried hard to stay but gave up after 6 months and joined another lab. The lesson I learnt: Quit (as soon as possible) if you are not respected or treated properly. A mentor who does not provoke thought or gives you the freedom to ask questions, will likely not aid your career much. Choose your research mentor wisely. You can not do science when you have a micro-manager or a bad human for a mentor.
  4. During my undergraduate, I was selected for a presentation for a national-level scholarship. I researched hard for a project on neural tube defects and but I was not well prepared for the presentation. And thus I failed to get the scholarship. Lesson learnt: Bad communication or presentation skills will dampen your science. Work on them, ask for feedback from your mentor and lab mates. Do mock presentations, write notes, try recording and listening to them to improve your sentences and script.
  5. While I was doing Ph.D. I never explored anything beyond my lab. But during postdoc, I started attending various courses on entrepreneurship and leadership skills. This helped me start my own company (Scipreneur). Researchers seldom explore things beyond their labs. Remember, your network is your net worth. Try to participate in courses, meetings, competitions, and networking events. Use social media wisely and to your benefit. Read biographies, listen and watch good talks and podcasts. They will help you in multiple ways. Like how to manage stress and time, how to cope with failures, how to deal with relationship hurdles, and how to envision your future with a better goal? Do more informational interviews, where you ask an expert’s time to discuss how they achieved their goals.
  6. Entrepreneurship was always on my mind but I never explored it as I felt I lacked the skills required. I failed to start on some interesting ideas and later found that someone had worked on them successfully. It took me 6 to 7 years to realise that Ph.D. and postdoc leverage us with so many traits like leadership, mentoring, communication, negotiation, perseverance, collaboration, and entrepreneurial skills. Do not undervalue yourself. Learn to swim beyond your safe zone and against the currents. It will not only boost your confidence but also enhance your ability to cope with challenges.
  7. I have seen researchers working day and night but failing to achieve big. Donkey work will seldom give you great science and big breaks; smart work will. You need to polish your ideas, questions, plans and execution. Teamwork is dream work, so never hesitate to ask for help. Collaborate and discuss with peers. I also learnt to use technology in the right way to accelerate the pace of research and increase efficiency. For example, use software and languages for better and fast analysis, LinkedIn for better collaboration and learning, Evernote for writing and as a virtual notebook, simple web-based software for colony counting and standard curve plotting, and different online tools to make beautiful figures and presentations.

We cannot predict failure, but we should keep the lessons learnt imprinted in our minds. Collaborative learning and sharing help us see mistakes more positively. Failures can rewire our brains and give us the confidence to approach problems from a different angle. They force us to question our hypotheses, plans, protocols, execution, and experimental setups. The greatest thing a scientist can discover is “a novel or better question”. Give yourself permission to fail and explore.

Genetic sequencing tools key to pandemic fight

Indian-born British chemist Shankar Balasubramanian recently won the Millennium Technology Prize, instituted by the Technology Academy Finland, for development of revolutionary DNA sequencing techniques. Vanita Srivastava caught up with him to understand the award winning genetic sequencing work that has widely impacted the fields of genomics, medicine and biology.

[Shankar Balasubramanian is a Herchel Smith Professor of Medicinal Chemistry in the Department of Chemistry at the University of Cambridge, a Senior Group Leader at the Cancer Research UK Cambridge Institute and a Fellow of Trinity College, Cambridge. He won the one million euro prize jointly with David Klenerman.]

Shankar Balasubramanian

University of Cambridge

Q. Tell us about your genome sequencing technology and how it has impacted the course of the COVID-19 pandemic.

A. Prof David Klenerman and I are co-inventors of Solexa-Illumina Next Generation DNA Sequencing (NGS). The technology was fully developed at Solexa into an integrated, commercial system, then further improved by the team in Illumina. This technology has enabled fast, accurate, low-cost and large-scale genome sequencing, which is the process of determining the complete DNA sequence of an organism’s make-up.

During the pandemic, NGS has been providing an effective way to study SARS-CoV-2’s genetic make-up and help us track the viral mutations, which continues to be a great global concern. This work has also helped the creation of multiple vaccines now being administered worldwide and is critical to the creation of new vaccines against new dangerous viral strains.

Q. India is now a hotspot of coronavirus mutants. How can this technology help address problems relating to this?

A. By studying and understanding the genetic make-up of the new mutant using our technology, we can identify its potential as a new threat by knowing how it differs from the other variants. Further, I hope that our technology can be useful in sequencing the genomes of people who have had COVID and trying to get an understanding of why some people are severely affected by the disease and others are asymptomatic. This approach could identify risk factors in specific people that may also be applicable to other viruses in years to come.

Q. What other potential use does this technology have?

A. The technology has a huge transformative impact in the fields of genomics, medicine and biology. It is being applied widely in the basic research of living systems, as DNA and RNA are fundamental to cells and organisms. Aspects of living systems include genetics, the expression of genes, the structure of DNA in the nucleus and differences between cells, to name but a few.

The technology is beginning to be applied in medicine, particularly in the areas of cancer and rare diseases. The applications in medicine will grow as we sequence more human genomes allowing the idea of personalised medicine where diseases are more optimally treated by understanding the individual and the drugs that are used are designed to correct the molecular pathway that has gone in a specific person. It will also be used in agriculture to breed species with desired properties.

Over the past few years, there have been tremendous advances in cancer, both with therapy and also detection and diagnosis. Over the coming decades, the goal is to use this technology to help make some cancers become manageable diseases because they are detected sufficiently early and it’s clear what has to be done. This could also hopefully be extended to other complex diseases such as heart disease and Alzheimer’s disease.

Q. What are the challenges to personalised genomic medicine?

A. Developing an effective and efficient infrastructure for sequencing patients on a large scale and using their genetic profile to help make the decisions in regard to the prevention, diagnosis, and treatment of their disease is currently the biggest challenge.

How outreach blends my worlds as a scientist and mom

Karishma S Kaushik, an Assistant Professor and Ramalingaswami Fellow at the Institute of Bioinformatics and Biotechnology in Savitribai Phule Pune University turned the pandemic into an opportune time to spur children’s interest in science, including her own son’s.

Karishma with son Abhay.

My phone pinged in the middle of the session. It was a message from my almost 10-year-old son. “Spelling mistake in slide 36. Instead of 1st you wrote ist” – the message read. I chuckled. Here I was, conducting a summer science quiz for children and their families across India, and getting instant feedback from the next room in the house. This was a heart-warming moment. It effortlessly represented how in a pandemic-stricken year, science outreach bridged my worlds as a scientist and a mother.

The pandemic forced a nation-wide lockdown in India in March 2020. It was around this time that my research colleague Snehal Kadam and I co-founded Talk to a Scientist. Schools were closed and I was giving informal science lessons to my son at home. He had so many questions – What is this virus? What is a pandemic? Why do we need to wear masks? Does the virus spread through food? As our science conversations gathered steam, I saw an opportunity in this rather distressful time to get children interested in, and excited about, science. I asked my son, “Do you think other kids your age, your friends for example, would be keen to talk to a scientist about all that is going on?” He was excited, “That would be great mom, but not just COVID, other topics as well.”

The first session of our webinar series went live on March 30, 2020, befittingly on COVID-19 for kids. Snehal and I made the visual content for the session, and I ran it by my son. He made edits and suggestions, and we got ready to roll. We expected 5 children to show up, and I was counting on my son and his cousins to be three of them. Much to our surprise and excitement, we had 75 children from across India join in. On popular demand, we started a weekly webinar for young minds.

The project has grown, and my son and I have spent hours brainstorming. For a session on medicines, he asked us to change the word ‘drug’ to ‘medicine’ on the slides. ‘Kids should not think you are talking about those kinds of ‘drugs’ that make people woozy, mom!” he said. I laughed and thought, my son is growing up. When I suggested a theme for a season, he would quickly come up with names from among my colleagues to be the guest scientists. “What about that scientist who works on peafowls, you shared a room with her in the Delhi conclave?” He has been a part of my professional life through conversations and conference books I brought back home, and now he was using it all to contribute to our outreach programme!

On the momentous occasion of us winning a grant to grow the platform, he stood near me, jumping with excitement, as I called Snehal to tell her the good news. Through weekly sessions spread over one year, he has enjoyed doing small jobs for the outreach – suggesting new features in the website, ideating for hands-on sessions with home supplies (as a parent myself, I did not want families to go out shopping for supplies in the middle of a pandemic), checking for typos in the slides, and sending flyers and posters to his school friends. For him, the ownership and importance of being a part of a national outreach programme has been thrilling. I would like to think that he will grow up to remember how it all started, with a casual conversation between us at home, and the time we spent together growing it in what was otherwise a tough year.

For me, in a year filled with professional uncertainties, pressures of working from home and home-schooling, science outreach has been a beautiful amalgam of my roles as a scientist and a mother. When the world was turning to science for answers, the scientist in me wanted to contribute to science outreach and education in the country, by sharing the process of scientific discovery and its power to transform lives and livelihoods. That I could co-create this with my son made this initiative even more special. Since the time I was a pregnant PhD student, determined to balance my life and career as a scientist and mother, I have day-dreamed scenarios where my son and I would talk about scientific advances, when he would join me on conference trips, and even imagined the possibility of us working together some day. I would like to believe that ‘Talk to a Scientist’ is the beginning of this journey.

While there have been numerous fun moments, one has been extra special. In the middle of one of the sessions, I caught my son taking a snack break in the kitchen. I looked at him questioningly, “Why are you not attending the webinar?” He replied matter-of-factly, “Your slides got a little boring mom, I will help you make better ones for next week”.

In addition to correcting typos, such no-filter feedback has been part of the deal!

Attending the APS March Meeting 2021

Guest post by Andrea Richaud, recipient of the Communications Physics 2020 Early Career Researcher grant which enabled him to attend a conference or scientific school of his choice.

In December 2020, I had the pleasure to receive the 2020 Training Grant for Early Career Researchers from the journal Communications Physics. After defending my doctoral thesis in February 2020, I joined SISSA (International School for Advanced Studies, Trieste, Italy), where I am now post-doctoral researcher in the Condensed Matter section.  The focus of my research is on SU(N) fermionic systems, their possible topological phases, and their possible use as quantum simulators of multiband solid-state models. This is an active research field, as ultracold-atom-based platforms illuminate the intimate physics of strongly-correlated systems, by getting rid of a number of spurious effects (like crystal defects) which are inevitably present in standard solid-state systems.

As an awardee of the ECR training grant, I decided to attend the APS March Meeting 2021, a very important conference which involved more than 11,000 different researchers from all over the world. Despite its virtual form (due to the persistent pandemic situation), attending this conference was a very positive and stimulating experience, as I had the possibility to watch tens of very interesting seminars encompassing several aspects of my current research activity. In particular, I found it useful to attend seminars focusing on experimental aspects of the topics which I investigate at the theoretical level. Even as a theoretician, I think that being up to date with experimental advances is really crucial, as one can get valuable ideas and correctly interpret the open problems.

Andrea attending the conference

In spite of the virtual form of the conference, I managed to have a good interaction with many speakers, asking them questions and sharing ideas about common research topics. This was possible thanks to the presence of “Zoom networking rooms”, which were made available at the end of each session. Of course, they could not fully replace a good traditional coffee break, but l think that they worked well enough for this pandemic situation.  Among the advantages of attending such a large meeting virtually, the online platform made switching between rooms pretty easy (compared to running down corridors in a conference centre) and every seminar was recorded and made available to the attendees to re-watch. I am very grateful to the journal Nature Communications Physics for awarding me the prize which allowed me to take part to the APS March Meeting 2021. I definitely think that this experience has been very beneficial for my career as a young researcher.

Diversity leads to impact: what we learned from running an inclusive and accessible physics webinar series

Contributed by the following authors (in alphabetical order): Dr Claudia Antolini, Dr Clara Barker, Dr Kathryn Boast, Dr Izzy Jayasinghe, Dr Caroline Müllenbroich, Dr Clara Nellist

Why we launched a webinar series

2020 has seen an explosion of physics webinars. Many of these came about out of necessity to adapt established seminar series and conferences to suit the restrictions around the COVID-19 pandemic. Others were the realisation of an opportunity to bring together researchers and audiences that would typically be restricted by geographic separation or time commitments.

In this time, it soon became apparent to a number of us in the advocacy group TIGER in STEMM that women, people of colour, people who are LGBTQ+ and people who have disabilities were under-represented in online physics panels and webinars, and that speakers from marginalized demographics and identities were not always afforded the visibility and courtesy that is usually expected in the field. Moreover, considerations for adequate accessibility to the broadcast were often overlooked.

Banner for the TIGER in STEMM 2020 summer webinar series

Banner for the TIGER in STEMM 2020 summer webinar series

The six of us, women with a connection to the UK physics landscape from different areas of physics, diverse backgrounds, and identities, were determined to successfully demonstrate a different approach to online physics webinars. Recognising the need to place the same importance on diversity, inclusion and accessibility as on the physics that would be showcased, we set out to create a series of talks that break the mould and establish a precedent of providing an equitable platform for communicating science to academic peers and the general public alike. Within four weeks of initially coming together, we launched the inaugural TIGER in STEMM summer webinar series in physics on the 6th of August 2020. We wanted to celebrate intersectional and marginalised physicists (see Figure 1) and offer them centre stage to talk about their research. Our vision was to demonstrate that incorporating diversity, inclusion and accessibility compromised neither the impact nor the quality of the scientific discussion. More than that, we strived to prove that by placing these values and principles at the core of our enterprise, scientific discussion and dissemination would be enhanced and the impact of this style of communicating science would be amplified.

What we (and you) can learn

Diversity leads to impact. From an event which ran as a brief and self-contained series of webinars, the learnings were rich. With a total audience nearing 1000 people over the duration of the 5 event series, it was clear that prioritising diversity on an equal footing as achievements of the speakers enhanced the engagement with the event. There were no compromises made on the depth of the science presented on this platform, which is evidenced by the recordings of the lectures which are still publicly available for viewing.

A support network is key. A series such as this was only possible with the unwavering support of TIGER in STEMM, particularly through endorsement of the conviction that diversity can only enrich science, technology, engineering, mathematics, and medicine (STEMM) fields. At a time when online physics conferences and workshops heavily feature speaker line-ups and panels dominated by white men, stepping up to demonstrate impact through a contrasting set of objectives required strength and every bit of support that the six of us could get. Also, the practical support of the group, for example taking advantage of the substantial follower count of the TIGER’s Twitter account and amplification of that advertisement by group members, was fundamental to the success of the physics webinar series.

Accessibility is more difficult but not impossible without a budget.The plan to organise a webinar series came together over a noticeably short period of time and we had no budget. This came with its own set of limitations. TIGER in STEMM do not hold funds so we had to rely on freely available resources. Firstly, we struggled to find free software support for captioning the presentations and Q&A sessions during the webinars. We found that the live subtitles of Microsoft PowerPoint worked best during the live broadcast, however this was subject to the version of software each presenter was using. Irregular captioning was in fact the single most frequent criticism that we received on our approach. Incorporating either live captioning via a scientific captioning service or sign language interpretation would have added a considerable amount of value and accessibility.

Timing and frequency require careful consideration. The decision to schedule the series for consecutive weeks in August and early September when most university academics, school teachers and students are on vacation may have amplified the webinar fatigue among our audience. While it could be due to the unique amount of stress that 2020 has generated, we acknowledge that this was particularly evident from the limited survey feedback that we received after the conclusion of the series. So, timing should be considered as a factor for accessibility and engagement.

Diversity attracts diversity. Webinars and platforms that promote and safeguard diversity and equity are a powerful medium to attract a diverse audience. As clearly shown from our feedback survey, this positive feedback effect yielded an even greater representation of minoritised people in our audience than is seen in the general UK population.

Read more

International Women’s Day

Women’s Day was originally conceived at the turn of the 20th century and used in many countries as a focal point for the women’s suffrage movement, and other equal rights for women. 8th of March became a national holiday in the Soviet Union in 1917 after women gained suffrage there. It was recognised by the United Nations in 1977 and continues to be celebrated around the world in different ways. Today we commemorate the lives of three inspiring women physicists.

Florence Martin (1867-1957)1,2

Florence Martin enrolled at the University of Sydney in 1891 and successfully completed a year of physics classes. During her second year, she began working as an unpaid research assistant to Richard Threlfall who was a family friend. In 1893 she wrote her first paper with Threlfall, verifying Maxwell’s equations in magnetic circuits (pictured). 

Journal and Proceedings of the Royal Society of New South Wales 

After this, Threlfall introduced Martin to his old friend, J J Thomson at the University of Cambridge and Martin sailed to England to spend three years working with Thomson at the Cavendish Laboratory. Here she took undergraduate practical classes and pursued her own research on the gas expansion caused by electric discharge. When Martin returned to Sydney she worked with Threlfall for another two years, until he left for England. This signalled the end of Martin’s career in physics. 

In 1905, Martin met a wealthy American couple and spent the next few years travelling the world with them. When the couple died in 1918, she inherited their estate in Denver, Colorado. She settled there, and spent the rest of her life as a patron of the arts.

Wang Ming-Chen (1906-2010)3,4,5

Baidu Bai Jiahao

Wang Ming-Chen studied physics at Ginling College, Nanjing and at Yanjing University in Beijing. After receiving her Master’s degree from Yanjing University in 1932, she applied for a scholarship to study abroad. Despite gaining top marks in her class, she did not qualify and had to return to teach in Ginling College. She remained there until the Japanese invasion of 1937, when she fled to Wuhan. In 1938, Wang was able to move to the USA for doctoral work and earned her PhD in statistical mechanics from the University of Michigan in 1942. For the remainder of the second World War, Wang worked at the MIT Radiation Laboratory (where wartime radar research was taking place). During this time, she published “On the theory of Brownian motion II” with G.E. Uhlenbeck.

After the war, Wang returned to China and became a professor at Yunnan University in 1946. However, she only stayed for a few years and returned to the USA in 1949 to work at the University of Notre Dame. However, as political tensions between the US and China increased during the period of McCarthyism in the US, Wang was regularly harassed by the FBI. She applied to return home in 1953, but it took two years for this to be approved and she only came back to China in 1955. 

Wang became a professor of physics at Tsinghua University in Beijing. At this time there was a strong focus on teaching in China, and Wang stopped her research in order to teach courses on statistics and thermodynamics. During the Cultural Revolution of 1966, she was arrested and imprisoned for seven years, on account of her husband being a political target. Later, she told a friend that she focussed on exercising every day in prison to “remind myself that I can’t die, I must live, and I must restore my innocence.” Released in 1973, she continued working at Tsinghua University until her retirement in 1976. 

Carolyn Parker (1917-1966)6,7

Who’s Who in Colored America 1950

Carolyn Parker graduated magna cum laude with a Bachelor’s degree in mathematics from Fisk University, Tennessee, and went on to receive a Master’s degree from the University of Michigan in 1941. This made her the first African-American woman to receive a postgraduate degree in physics. After her graduation she taught physics and mathematics in various public schools for a couple of years. 

In 1943, Parker started working in the Manhattan project, which was developing atomic weapons during the second World War. She was based in Ohio, at the Dayton project, conducting research on using polonium as an initiator for atomic explosions. Due to the secretive nature of the research, not much is known about her work in this period. After the war ended, Parker left the Dayton project and continued further study at the University of Ohio. 

Parker earned a second Masters in physics from MIT in 1951 . She continued research, partially fulfilling the requirements for a doctorate, however, she did not go on to defend her dissertation. Parker died at the age of 48, from leukemia, believed to be caused by her exposure to polonium during her time at the Dayton project.



  1. Florence Martin, Australian National Dictionary of Biography Accessed 08.03.21.
  2. Journal and Proceedings of the Royal Society of New South Wales, Biodiversity Heritage Library, Accessed 08.03.21.
  3. Ming-Chen Wang, Rackham Graduate School, University of Michigan Accessed 08.03.21
  4. Ming Chen Wang, Kai Zhang personal website, Accessed 08.03.21
  5. Wang Ming-Chen, Wikipedia Accessed 08.03.21
  6. A. Powers, The First African American Woman To Obtain A Graduate Degree In Physics Was Involved In A Top Secret US Mission, Forbes 2020 Accessed 08.03.21
  7. Carolyn Parker, Wikipedia Accessed 08.03.21

Light and matter in sync

Contributed by Saar Nehemia and Ido Kaminer – Technion, Israel Institute of Technology.

In 1934, Pavel Cherenkov discovered that when charged particles surpass the speed of light in matter, they generate an electromagnetic shockwave. A well-known analogue for this phenomenon is a sonic boom – shockwaves of sound generated when jet planes surpass the speed of sound in air. This new understanding of light–matter interactions led Cherenkov to share the 1958 Nobel Prize in Physics with Ilya Frank and Igor Tamm for his experiment and their theory. The Vavilov–Cherenkov effect has been studied extensively since then and besides being of fundamental science importance, it has led to applications in particle identification, medical imaging, quantum cascade lasers, optical frequency combs, laser-driven particle acceleration, and other areas of nonlinear optics and nanophotonics

In 2020, our paper in Nature Physics demonstrated an experimental signature of a quantum Cherenkov effect. In this post, we take you behind the scenes of our experiment.

The quantum Cherenkov effect

The Cherenkov interaction and analogous effects were mainly studied in the context of classical physics; however, some scientists were interested in their quantum description. The first to study the quantum nature of the Cherenkov effect were Ginzburg and Sokolov in 1940. The conclusion from their work was that quantum corrections to the Cherenkov effect are negligible and irrelevant. In a later paper from 1996, Ginzburg even states that “In 1940, L D Landau told about my work stated that it was of no interest. It follows from the above, that he was fully justified in drawing this conclusion, and his comment hit the mark as was usual with his criticism”. For many years, this statement and related beliefs created a conception that kept scientists away from studying the quantum Cherenkov effect.

A series of theoretical papers from the past 5 years revisited the quantum Cherenkov effect and ignited a new interest in its consequences, starting with our theoretical paper from 2016. These papers predicted interesting consequences for a quantum treatment of Cherenkov-type effects and envisioned that modern experimental capabilities and advances in electron microscopy and in quantum optics could lead to the demonstration of quantum Cherenkov-type phenomena.

Over the last couple of years, other scientists began to predict similar theoretical features in related effects, such as the Smith-Purcell effect (see work by Talebi, Gover, Arie, Polman, and Garcia de Abajo). All these effects can be considered as Cherenkov-type because they all share the same underlying principle: an enhanced interaction between a charged particle and light that occurs when the velocity of the particle matched the phase velocity of light – also termed phase-matched particle–light interaction. These theoretical findings increased the general interest in building an experiment to test these theoretical predictions.

Illustration of the electron-laser interaction, inspired by Pink Floyd’s cover art of Dark Side of the Moon. Each electron is coherently split into a wide energy spectrum (rainbow). The laser light (red) has to be coupled at a precise angle to achieve the strong interaction, in which the electron simultaneously absorbs and emits hundreds of photons from the laser.

Morgan H. Lynch and Saar Nehemia, Technion AdQuanta lab.

There exist three types of quantum effects that can occur in phase-matched particle–light interactions.

  1. Recoil corrections due to the quantization of the electromagnetic field. The emission occurs in quantized packets, creating a deviation from classical theories of radiation emission. This effect was first analyzed in 1940 by Ginzburg and Sokolov, in the context of the Cherenkov effect.
  2. Intrinsic changes to both the charge dynamics and the emission properties due to higher-order processes in QED. These effects include photon re-absorption that causes an electron mass correction (analogous to Lamb shift in renormalization theory), all being effects that cannot be explained classically.
  3. Phenomena due to the quantum wave nature of the charged particle, with features that cannot be explained by a classical point-charge description, such as the emergence of discrete energy peaks in the electron energy distribution. This is what we measured in 2020.

Our paper

In our recent work, we measured the third type of the quantum effects described above. To demonstrate the Cherenkov-type interaction, we launched a laser pulse through an optical medium (see prism, below) to synchronize its velocity with a highly-collimated electron beam passing nearby. Using a very accurate electron energy spectrometer (as used in the EELS technique), we measured the electron energy distribution and revealed the discrete energy peaks discussed above. The longitudinal profile of the electron wavefunction altered the interaction. Analogous quantum corrections also arise from transverse features in the electron wavefunction, as its orbital angular momentum (OAM) or its transverse spatial profile.

An optical microscope image of the prism used in the experiment. This 0.5 mm prism was attached to a 3 mm surface (darker background) with a square hole (center of image). The prism alignment was extremely precise to ensure that the electrons interact resonantly with the light in the prism. These electrons then pass through the square hole at the center of the surface.

The Technion AdQuanta lab.

Our experiment demonstrated a Cherenkov-type interaction between light waves and an electron wavefunction: the Cherenkov conditions are satisfied between an electron pulse and an incoming laser pulse that stimulates the interaction. This stimulated-Cherenkov effect is also known as the inverse-Cherenkov effect. The excitation laser pulse interacts with the electron at the Cherenkov angle (the same angle at which the radiation is emitted in the Cherenkov effect), resulting in a phase-matching between the electron and the laser light that leads to their strong interaction – causing both energy gain and energy loss – occurring simultaneously by each individual electron. In our experiment, this interaction is sustained over hundreds of wavelengths, causing the electron to become a coherent superposition of hundreds of energy levels.

Our setup is based on the ultrafast transmission electron microscope (UTEM), which utilizes femtosecond lasers for pump probe experiments. The microscope offers several degrees of freedom to measure the interactions between light and free electrons: controlling the delay between the light (“pump”) and the electron (“probe”), in addition to the light wavelength and polarization. The microscope allows us to control the electron wavefunction in space and time through its interaction with the laser.

Illustration of the UTEM set-up, showing the grazing-angle interaction with a prism.

Dahan et al. Nat. Phys. 16 1123–1131(2020)

Our Cherenkov experiment required a unique configuration that has never been achieved in a UTEM system, or in any transmission electron microscope: we needed to align the electron beam to graze the surface of our prism over 500 microns, while remaining at a distance of just 100 nanometers from the surface. To understand how complex this achievement is, consider that even samples that are 10,000 times thinner (nanometer scale, about the size of the corona virus or a couple of DNA strands) are considered quite thick in transmission electron microscopy.

To explain our results, we used the theory that was originally developed for a technique called photon-induced nearfield electron microscopy (PINEM), and extended it to describe our grazing-angle interaction. While all previous PINEM experiments dealt with localized interactions (in which the electron-light interaction spans over a single light wavelength or much below), our grazing angle experiment enabled the electron-light interaction to extend over hundreds of field cycles and hundreds of wavelengths. By satisfying energy–momentum matching over a long interaction distance and a prolonged interaction duration, the interactions become stronger by orders of magnitude compared to localized interactions – this opens the way to creating strong and ultrastrong coupling phenomena with free electrons.

Going back to the types of quantum effects that can arise in electron-light interactions, the PINEM interactions (see work by Carbone, Ropers and others) can be seen as an occurrence of the quantum effect of the third type – since it depends on the electron wavefunction. However, PINEM interactions before our work did not reach the Cherenkov-type interaction because they relied on localized fields (interestingly, even the acronym PINEM includes the word “nearfield”, although other types of fields can also create the effect).

The Cherenkov effect is only one example of phased-matched particle–light interactions. The energy–momentum phase-matching condition that is famously found in the Cherenkov effect also occurs in the Smith-Purcell effect, their inverse effects and a wide range of electron–light interactions that satisfy similar phase-matching conditions.

Looking Ahead

Simulation of the electron-laser interaction. The laser light (red-blue wave) interacts with the electron wavefunction (elongated sphere). This setup assures that the electron exchanges energy with the laser in a resonant manner – achieving the precise conditions of the Cherenkov effect.

Dahan et al. Nat. Phys. 16 1123–1131(2020)

In another recent study by our group in 2020, published in Nature, we measured the interaction of free electrons with light captured inside a photonic cavity (also measured at the same time here). Looking ahead, we envision combining the Cherenkov phase-matched interaction with an elongated photonic cavity as a route to achieving efficient electron-photon interactions. The cavity will channel emitted photons that can then be resonantly reabsorbed by the elongated electron, creating a strongly-coupled electron–photon hybrid. This hybrid will enable the exploration of extreme conditions such as single-electron–single-photon interactions, which can serve as a novel mechanism for number-resolved single photons detection.

Reaching this regime of physics would open previously unknown processes like free-electron Lamb shifts, controllable free-electron mass renormalizations, and potentially even cavity-mediated Cooper pairs of free electrons. These exciting prospects rely on the quantum interaction of free electrons with photons that are dressed by their optical environment – which enables the Cherenkov effect and many other future ideas.




Announcing winners of Nature India Photo Contest 2020

After a week of open voting for favourites, and selection by a global jury of Nature Research editors and designers, we are ready to roll out the verdict of the Nature India Photo Contest 2020.

The photographs have been judged for their adherence to this year’s theme ‘pandemic’, for their creative thinking, quality and print worthiness.

The winner of the Nature India photo contest 2020 is:

Partha Paul

for his powerful composition ‘Sampling immunity’, which has a child in the middle of the COVID-19 triangle, and symbols of the virus and the protective mother on either sides.

In Partha Paul’s words: “A health worker collects blood sample from a child in Kolkata, West Bengal as part of a sero survey to determine prevalence of SARS-CoV-2 in populations. In the middle of the COVID-19 pandemic, these surveys were conducted to determine what part of a population had developed antibodies. This was the first day of antibody tests in Kolkata’s Belgachia slum, one of the worst affected by COVID-19. This child, seen here with her mother, came from a ‘red zone’ where the government had enforced maximum containment measures.”

The second prize goes to:

Amitava Chandra

for his striking picture ‘Immersive innovation’, which makes a beautiful juxtaposition of faiths — of religion and of science.

Amitava Chandra says, “The annual Durga Puja festivities end with the immersion of the gods’ idols in river Hooghly, a tributary of the Ganges. Every year thousands of people take part in the idol immersion processions. Following COVID-19 restrictions, the festival organising committees created temporary water bodies to ‘immerse’ the clay-made idols by dissolving them with high power water jets, like in this picture taken at the Tridhara Sanmilani Puja Pandal, Kolkata on 26 October 2020. The benefits were two-fold – no processions, and no pollution of the Ganges’ waters.”

The third prize winner is:

Kaushik Dutta

for his imaginative picture ‘Migrant trouble’, which captures in the eyes of a child the threat of the pandemic symbolised by the ‘gun’ of the thermometer.

“Sending millions of migrant workers from across Indian cities back to their hometowns became a herculean task for the Indian government during the COVID-19 lockdown. This little girl boarded a train of migrant workers hoping to return home with her family. Unaware of the pandemic and what it means, she looks on with amazement at a healthcare worker in protective gear measuring her temperature with a thermal gun at the Howrah train station in West Bengal, India.”

Many congratulations to the winners!

The winners of the Nature India photo contest 2020 will get cash awards ($350, $250 and $200 respectively). They will receive a copy of the Nature India Annual Volume 2020 and a bag of goodies from Nature Research. One of the winning entries also stands a chance of being featured on the cover of a forthcoming print publication.

A special mention for all our other finalists (Deepak KumbharNila Nandi, Sandip Sarkar, Aishwarya Nilakhe, Sourav KarmakarAnindya Chattopadhyay), whose pictures portrayed various aspects of the pandemic’s socio-cultural impact. These pictures will linger in our memories for a long time.

Nature India Photo Contest 2020: Finalist #10

Marking the end of the shortlist, we unveil finalist #10 in the Nature India Photo Contest 2020 themed ‘pandemic’:

Kaushik Dutta, Kolkata, West Bengal

Photo Caption: Migrant trouble

“Sending millions of migrant workers from across Indian cities back to their hometowns became a herculean task for the Indian government during the COVID-19 lockdown. This little girl boarded a train of migrant workers hoping to return home with her family. Unaware of the pandemic and what it means, she looks on with amazement at a healthcare worker in protective gear measuring her temperature with a thermal gun at the Howrah train station in West Bengal, India.” — Kaushik Dutta

Congratulations Kaushik for for your second entry making it to the top 10 shortlist of the Nature India Photo Contest!

That brings us to the final picture in the 2020 Nature India Photo Contest shortlist. Watch this space for the announcement of the winners in the coming weeks.

The Nature India editorial and design teams have chosen ten stunning finalists, that will be rolled out (in no particular order of merit) over the next few days. These entries have been judged for novelty, creativity, quality and print worthiness. Nature India’s final decision to chose the winner will be partly influenced by the engagement and reception these pictures receive here at the Indigenus blog, on Twitter and on Facebook. To give all finalists a fair chance, we will consider the social media engagement each picture gets only during the first seven days of its announcement. The final results will be announced sometime in early February 2021.

Watch this space as we announce the other finalists in the coming days. Like, share and comment on your favourite photos on Twitter and on Facebook with the hashtag #NatureIndphoto to make them win.

The winning pictures will get cash prizes worth $350, $250 and $200 respectively. The top 10 finalists will be featured here, on Nature India’s blog Indigenus and in our subsequent annual issue.

The winner and runners-up will also receive a copy of the Nature India Annual Volume 2020 and a bag of Nature Research goodies. Winning entries stand a chance of being featured on the cover of one of our forthcoming print publications.