Haldane on the second quantum revolution

This week I attended a great public lecture by Duncan Haldane: "Quantum Mechanics After One Hundred Years, and the 'Second Quantum Revolution' Today"

Starting from the discovery of quantum mechanics, he explained how the concept of quantum entanglement is fueling today's second quantum revolution and its connection to his Nobel Prize-winning work.

Haldane remarked that his work on quantum spin chains was controversial. He had theorists accosting him at conferences arguing he was wrong. These kinds of disputes among theorists are best settled by experiment. Undoubtedly, Haldane would not have received his Nobel Prize if his predictions had not been validated by experiments. How can you motivate some experimental group to be interested in your theory? If it generates controversy!

Similarly, experiments often are the drive for fresh theoretical advances. For example, the experimental discovery of the quantum Hall and fractional quantum Hall effects came before the theoretical predictions or understanding. 

A good example of this is a second important work by Haldane also cited in his prize: quantum Hall effects in absence of Landau levels. This now-seminal work went largely unnoticed for a decade, because the model based on a two-dimensional honeycomb lattice seemed unfeasible to realize in an experiment. Later, the unanticipated work experimental isolation of graphene drove theorists to this fresh area. Haldane's early theory work was recognised as the foundation for the discovery of time reversal-symmetric topological insulators and the whole "zoo" of topological materials that followed.

Haldane also emphasized the importance of luck in making ground-breaking discoveries. von Klitzing was not the first person to attempt quantum Hall measurements, but previous attempts had used a different experimental setup: varying current with a fixed magnetic field. Imperfections in the current source led to fluctuations in the measured resistivity, which seemed to be consistent with previous approximate theoretical calculations based on perturbation theory. von Klitzing's approach of measuring resistivity as a function of magnetic field strength, with current kept fixed, led to unexpectedly precise quantization which needed new theory to explain. 

Haldane's take-home message was thus: anyone can win a Nobel Prize, but you need luck and the perseverance to defend your work if it is challenged.

An earlier iteration of this talk is available here. A more detailed write-up is available here. 

   

Quantum Computing Summer School at Los Alamos National Laboratory

The Quantum Computing Summer School is an immersive 10-week curriculum that includes tutorials from world-leading experts in quantum computation as well as one-on-one mentoring from Los Alamos National Laboratory staff scientists who are conducting cutting-edge quantum computing research. Summer school fellowship recipients will be exposed to the theoretical foundations of quantum computation and will become skilled at programming commercial quantum computers, such as those developed by IBM, Quera, IonQ, Quantinuum, DWave. All students (undergraduate and graduate) are encouraged to apply.  

In the first 2 weeks, students will attend lectures given by world-leading experts – from academia, industry and national laboratories – in quantum computing research. Following the 2-week lecture period, each student will work on a research project in quantum computing for the remaining 8 weeks. For this research project, each student will be paired with a LANL mentor who will propose project topics and provide guidance. Each project will involve some hands-on programming of a quantum computer (IBM’s, Quantinuum’s, Quera, D-Wave’s, as available). If time permits, the students will begin preparing their results for publication.

This is an fantastic opportunity with so many of the student projects delivering important findings on various hot topics related to quantum computing. This is a testament to the quality of the mentorship provided by the staff scientists involved in the school.

More information including how to apply is available here. The application deadline is January 11th, 2026.

2025 in review

I was sad to hear that my former workplace, the Center for Theoretical Physics of Complex Systems, is winding down. It was such a great academic environment with time to think and ample opportunities to learn from colleagues and the regular seminars and international workshops. From the Center's last Scientific Report:

Outlook: The center counts 492 publications, a total of 12813 citations, and an h-index h = 56 on Google Scholar. Despite its tremendous success, a continuation with a new division headed by a new director could not be realized by IBS, which is a pity and raises other IBS related questions which are not part of the current report. As a result of the foreseeable retirement of the current director, the PCS is winding down by the end of 2025. Practically all members of the PCS quickly found or are successfully securing new positions in research institutes and universities worldwide. The successful concept of the PCS will continue to exist through its alumni who carry the message into the world. These include twenty three (23!) faculties worldwide, including eight (8!) in Korea, six (6!) in China, and five (5!) in India, but also in Singapore, Vietnam, Brazil, USA, and the Philippines.

It's a real shame, especially since support for similar theory-focused research centers is so limited. Short term grants promote "safe" topics rather than giving researchers the time and freedom to follow their curiosity and try new ideas.

Looking back, memorable moments at PCS include:

• A visit and seminar in 2018 by J. Michael Kosterlitz in which he recounted his unusual journey to his Nobel Prize-winning work, including the important role played by job rejections and rock climbing. We didn't record his talk, but what seems to be a similar version can be found here.
• Workshop weeks, particularly the ability to sit in on workshops beyond one's own areas of expertise and get a first-hand glimpse of how informal interactions differ between different fields. Sometimes the welcome reception and evening activities would wind down within an hour or so, other times they would continue into the early morning, prime time for forging new collaborations and hearing important gossip. This is also why online conferences are a poor substitute for in-person events. 
• We went through a period where we were required (as a government institute) to have personal identifying information in all job applications be anonymised, to eliminate bias in their evaluation. Whoever came up with this didn't understand you cannot anonymise academic CVs - the publication list will inevitably give the name away!

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Physical Review A saw a significant increase in submissions, including some LLM-written papers. When used properly, LLMs can be a great productivity enhancer, particularly for non-native English speakers. On the other hand, if one uses the LLM to "cheat" and write the paper entirely, it is really easy to spot. Some dead giveaways: formatting, em-dashes, fake references, overly wordy text that doesn't say much (or makes no sense at all). 

For similar reasons it is easy to spot when a referee report (or student homework assignment) has been prepared using an LLM instead of real intelligence! During one of my classes this year, I was sad to see some students completing their hand-written humanities assignment by directly copying the output from ChatGPT. At the end of the day, tedious "homework" like unpaid reviews are not just a box to tick off, they are exercise for your mind. By looking carefully for flaws and inconsistencies in someone else's work, you are also developing the critical thinking skills that will improve your own writing and research. Don't short-change yourself by delegating to an LLM!

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My own research is going at a slower pace. A lot of thinking time has been replaced with grant-writing. I hope to see some payoff for this substantial effort in 2026!