“She is so humble and inspires a lot of people” – Dr Amelle Zaïr on working with the 2023 Physics Nobel Prize winner

Tell us more about this year’s Nobel Prize in Physics?

The 2023 Nobel Prize in Physics was awarded to Pierre Agostini from Ohio State University in the US, Ferenc Krausz from the Max Planck Institute of Quantum Optics in Germany and Anne L’Huillier from Lund University in Sweden for “experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter”.

Over decades of experimental work, the laureates developed methods to producing pulses of light so short that they are measured in attoseconds (1ase=10^-18 sec). These attosecond pulses were the shortest flashes of light ever produced, and enabled scientists to study the dynamics of electrons in physical matter for the first time ever. This has subsequently led to a revolution in photonics – the science of ultrafast light waves – enabling new insight into the world of electrons, which play a key role in many phenomena we see every day, from electricity to magnetism.

I was lucky enough to work in Anne L’Huillier’s lab on several experimental campaigns which demonstrated the measurement of attosecond pulses during my PhD, and have collaborated with her throughout my career, including on a publication this year.

Looking back, it was amazing to work in this pioneering research area, I learnt a lot from Anne and her group, and these experiences inspired me to continue research on attophysics and the ways it could revolutionise a range of emerging research areas, including quantum technologies and pharmacology.

Why are attosecond pulses exciting?

An attosecond is a billionth of a billionth of a second – so it’s incredibly fast! Infinitesimally small objects such as electrons in atoms and molecules move at attosecond time. Hence, if you want to study the motion of electrons, the only way to follow their motion is to develop a flash of light- with lasers that are as quick as an attosecond.

It’s a bit like if you were to take a photo of Usain Bolt running, you would need a camera with an extremely fast flash that moves quicker than he runs, otherwise you would end up with a blurry photo and you would miss the chance to investigate and understand his incredible ability.

The same is true of electrons, using an extremely short flash of light such as the attosecond pulses, you can take ‘snapshots’ of an electron and manipulate it in quantum systems. The Nobel Laureates' discovery opened up the route to capturing, for the first time, snapshots of electrons behaving like a wave – ie under the laws of quantum mechanics.

By allowing us to enter the attosecond realm, this has not only revolutionised our understandings of fundamental science, but is now leading to a whole new era of technological innovation – with the dawn of quantum computing.

This year’s Nobel Laureates have inspired us to become the second generation of attoscientists. At King’s, the Attosecond Quantum Physics Lab I lead is one of only two laboratories in the UK on experimental attosecond physics based on high harmonic generation. We investigate this emerging research area along with our esteemed colleagues at Imperial. We have innovated in cutting edge laser technology, and our broader interdisciplinary understanding is enabling us to advance the next attosecond physics discovery to concrete applications – something fairly unique to King’s in the UK.

My hope is that with the leadership, unique expertise and talent in attophysics in the UK, we can grow even further with strategic investment, potentially developing a centre for attosecond science, and in the creation of spin offs for developing technology with socio-economic impact.

What was it like working with a Nobel Laureate?

I’ve had the most incredible opportunity to collaborate with Anne since my PhD. As a postgraduate researcher in Bordeaux, France, thanks to my supervisors I was part of an EU network led by Anne which included student mobility, allowing me to join her lab in Lund for a period of time. This was one of the best collaboration experiences of my career. I learnt a lot from her as she’s so dedicated to her students and she’s an amazing teacher and passionate about transferring her knowledge.

As part of the network collaboration, I worked on several experimental campaigns which demonstrated the measurement of attosecond pulses. Back in Bordeaux, I continued with the experiments, including a control of the high harmonic to create isolated attosecond pulses, demonstrated by Ferenc, one of the other Nobel winners.

How did this time inspire you in your research career?

Continuing in this research area as a postdoc, I was the first ever scientist to do an experimental demonstration of a phenomenon called quantum path interferences in high harmonic generation. The best way to explain it is to take the idea of a boomerang – when you throw it, it comes back to you after acquiring kinetic energy from travelling. The same is true of electrons, except that in the quantum world the electron can follow more than just one trajectory to acquire the same kinetic energy. The electron is therefore doing a very funny thing, it is in a superposition of states. The measurement I did was to show that these electron trajectories can interfere with each other, which I found absolutely fascinating!

Quantum path interference was an important demonstration to make experimentally, because interference is known to be the observable phenomenon that unequivocally establishes the quantum properties of matter – so I’m really proud. Anne was particularly excited about my work, and I was lucky enough to continue collaborating with her, including recently through a consortium made of her group, my former PhD group in France, one of our long-term collaborative colleagues Professor Vasily Strelkov, as well as a company we have been working with on the application of attophysics to metrology technologies.

I am so thankful for everything I learnt from my PhD group and from Anne as well as members of her incredible group of attophyscists who were pushing boundaries at that time. She is so humble, but she has a wonderful mind, and it goes to show that when a supervisor is as dedicated and passionate as she is in sharing her knowledge, it inspires a whole generation of scientists. Hopefully in a few decades time, our community can win a second prize in attophysic applications continuing the legacy.

Tell us more about the pioneering research your lab at King’s is carrying out?

Our approach is based on the understanding that electron dynamics in matter are the building blocks of fundamental quantum physics, and this reveals fascinating insight into the quantum world. If we can see and control electrons, we can control and encode matter itself – enabling an exciting range of application.

My vision is to bring attosecond physics to revolutionise the world of quantum computing. At Attophysics at King’s we have the unique combination of expertise and the motivation to achieve this. I am proud to have in my group fantastic early career scientists who are  Royal Society University Research Fellows, Dr Emilio Pisanty and Dr Margarita Khokhlova.

We are playing on King’s strengths in multidisciplinary research and the application of scientific phenomena to advancing innovation and technology. For example, Emilio is looking at quantum optics whilst Margarita is working on applications for pharmacology, as attophysics can shed light on chirality which influences the behaviour of molecules in catalysis or chemical reaction, this in turn advances our knowledge of pharmacology.

In terms of my research, I am exploring how we can merge attophysics with quantum information processing and materials – to enable ultrafast processing for quantum computers. Quantum computing is going to revolutionise computing technology as we know it, enabling processing and calculations at speeds and capacities way beyond the best supercomputers we have today.

Ultrafast physics including attosecond physics is central to many disciplines, and I can foresee the impact it’s going to have in industry and in advancing new science frontiers. King’s was right to invest in this.

I’m so happy attosecond physics is in the spotlight, and in some ways wish I was a student today – because if you have a Nobel in your field, this motivates a lot of bright minds. The future is very exciting for us.