Condensed Matter Physics in the City (CMPC) is a long-standing conference series that has become a focal point for researchers in the UK studying strongly correlated materials. First held in 2010, the meeting was conceived by the Hubbard Theory Consortium – a confederation of condensed-matter groups from Royal Holloway, University of London, the University of Kent, the London Centre for Nanoscience at UCL, Imperial College London and the Rutherford Appleton Laboratory (RAL).

This year’s edition of the conference was scheduled to take place its traditional Royal Holloway location at Bedford Square in central London in July 2020, organized by a committee from across the Hubbard Theory Consortium and collaborators. It was to be complemented by a summer school on “Foundations of Quantum Matter” on the Isle of Skye, organized by our UCL colleagues Andrew Green and Frank Krüger.

Then the COVID-19 pandemic struck.

With excellent speakers lined up for both events, we still wanted to go ahead with the conference. But given the uncertainty of whether an in-person meeting would be at all possible, the organizing committee quickly agreed to take the meeting online.

Traditionally, CMPC has provided delegates with lots of time for discussion, offered an informal setting and struck a balance between theory and experiment, while involving junior and senior participants alike. This ethos is epitomized by our colleague Piers Coleman, based at Royal Holloway and Rutgers University, whose enthusiasm for getting theorists and experimentalists together derives from the early days of the field at Bell Labs, Bristol and Cambridge universities, and the Landau Institute.

Thanks to the previous events in the series, including last year’s 10th-anniversary conference, which had events spanning Paris and London, the core group of academics in the Hubbard Theory Consortium felt they were ready to tackle the challenge of recreating some of this conference experience online.

The organizing committee considered how best to ensure that the spirit of free-flowing discussion of our live events could be salvaged online

Through a number of Zoom meetings, our committee considered how best to ensure that the spirit of free-flowing discussion of our live events could be salvaged online. We therefore decided to deliver the conference as an interactive Zoom session, rather than a webinar, which would have allowed only a text-based Q&A channel from participants. To avoid the possibility of any unwanted “Zoom bombing”, we carefully screened conference registrations for authenticity and circulated session links only to registered participants.

From our initial e-mail announcement of the online conference going ahead, the uptake was rapid, with more than 2000 visits to the conference website within two weeks, and registrations from across the globe. To advertise, we only used established e-mail lists from previous events, while organizers e-mailed collaborating groups and people on RAL’s e-mail lists, courtesy of Devashibhai Adroja.

So quick was the response, in fact, that one of my collaborators from Iran had signed up even before I had a chance to mention the meeting in a personal conversation. Lots of registrations came from the UK, the US, India, Germany and Japan, with more from across Europe, Asia, the Americas, the Middle East, Africa and a few from Australia.

Overall, we counted some 670 registrations from people in 36 countries. Unfortunately, we did not collect information about nationalities, which may have been even more diverse. Our event had grown from a hub for the UK to a truly global event within a matter of days.

Encouraging online discussion

So how was the atmosphere of the online format? Unlike a live conference, we scheduled only two or three talks per day, which were held during UK afternoons to make attendance not too difficult for delegates in Asia and the US. Additionally, despite providing talks on YouTube, both live and as recordings, we were overwhelmed by many of our more remote participants’ enthusiasm to brave early mornings or late nights to attend live (the talk listings are still available via our schedule page).

With ample time allocated for discussions, the conversation really did take off despite the lack of face-to-face contact, and the event felt very interactive. There were no technical interruptions to report (except when our Zoom call crashed on the opening day, when numbers soared and we may have encouraged too many cameras to remain open).

The audience was extremely disciplined – especially thanks to the continual efforts of my colleague Sam Carr from the University of Kent to remind everyone of the meeting etiquette (adopted from the PQM group meetings at Kent) and occasional help from co-hosts to mute the odd microphone that had been left open unintentionally.

If anything, the option to ask questions both live by raising a hand, or via text-based chat seems to have lowered the barrier to making interventions, as many participants confirmed in our post-meeting questionnaire, and especially so for the student participants.

To engage students, who made up around 40% of the audience, we created new mechanisms, as the time-limited schedule did not allow the inclusion of additional live talks. Instead, they were allowed to submit pre-recorded talks, with the incentive of a prize for the best talk, which went to Alexandra Ziolkowska from the University of Oxford.

Overall, we were extremely impressed with the quality of student submissions, and there clearly was an audience to be found for them, with several videos being viewed more than 200 times at the time of writing. We also allowed students to lead additional discussion time after the formal sessions, which again drew a good participation, and was found to further lower barriers for participation.

Meeting new people

But what about informal discussions? Online conferences make it trickier to meet new people, get introduced to your long-time physics idols, or to hear or share the latest rumours and gossip. Nonetheless, we found the Zoom session provided a decent workaround, as the list of participants let you see who was there and to then chat to selected individuals or a small group of people.

Zoom provided a decent workaround, as the list of participants let you see who was there and to then chat to selected individuals or a small group of people

We’ve heard that many delegates used this opportunity to talk privately in the background, to follow up on discussion topics raised in the main session, or just make new friends. We also tried to stimulate face-to-face conversation by splitting the conference into break-out rooms during longer breaks, for which Zoom unfortunately only allowed random allocations. Personally, I found this worked surprisingly well on occasion, allowing me to meet a few random people and maybe discover common interests.

However, it really depended on having enough people actually willing to use the break-out rooms, rather than using the online format to “sneak out”, switch to another task or take a comfort break. Unfortunately, only a small number of participants engaged with us on social media, either via our Twitter channel or conference hashtag, though many indicated that our conference notice board had provided them with some helpful information.

From the responses to our post-meeting questionnaire, more than half saw their expectations towards online conferences raised (54%) and only a tiny minority had theirs lowered (4%). Advantages that were often mentioned included not having to spend time travelling and being able to fit in both personal work and conference attendance. Other benefits included not needing to hurry from one conference room to another, not having to worry about disturbing anyone if you arrived late, being able to have a drink, or quickly and discreetly switching to another task if needed. Also, delegates could drop in on the most relevant talks and discussions, while feeling fewer barriers to asking questions.

Several respondents from the developing world highlighted the fact that the online format had given them the chance to attend an event with top experts that they could otherwise not have afforded to attend in person (the event was free of charge). Negative responses were much scarcer, though quite a few people said that the 90 minutes we had allocated for talks – and 30 minutes for breaks – was too long, which meant we may have over-estimated people’s attention span. Excessive screen-time can be quite tiring in the long run, so maybe even shorter conference days would work out better.

Let’s meet again

In the future, we would love to meet colleagues in person again, and I hope our conference funding from the Institute of Complex Adaptive Matter (ICAM-I2CAM), EPSRC and the Institute of Physics can be carried over into 2021 to make this happen. But with the tremendous success of the online meeting this year, any future event, even if held “for real”, will surely have to have an online element associated with it too.

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Indeed, our survey indicated a healthy appetite for such a “hybrid” model, with about 30% indicating that they would actually prefer to attend the event online, and 40% wanting to attend at least in part virtually, maybe due to the reduced impact on time and travel commitments. Anyone wanting to keep abreast of announcements for next year can follow our Twitter channel, which also has coverage from the 2020 online edition.

Most of all, what this year’s meeting has confirmed is that there is a global appetite for a deeper understanding of novel materials properties at the quantum level. With topics ranging from spin liquids and neutral Fermi surfaces to novel superconducting states in twisted graphene bilayers and machine learning, we hope we have inspired researchers well beyond the people who usually attend our meetings.