Typically, excited atoms in open environments will exhibit dissipative and irreversible dynamics through the spontaneous emission of photons. However, by precisely positioning artificial atoms in the form of superconducting transmon qubits along a one-dimensional waveguide, we experimentally observed that the same photons that typically give rise to dissipation can also produce strong, coherent dynamics. This phenomenon is produced due to dynamical exchange between a single artificial atom and an emergent entangled state of the array. The ability to coax coherent dynamics from such a nominally dissipative system provides a route toward diverse applications like the generation of exotic quantum many-body states of light, quantum computing in decoherence-free subspaces, and multi-photon quantum state synthesis.
Every year, a committee of experts sits down with a tough job to do: from among all ICREA publications, they must find a handful that stand out from all the others. This is indeed a challenge. The debates are sometimes heated and always difficult but, in the end, a shortlist of 24 publications is produced. No prize is awarded, and the only additional acknowledge is the honour of being chosen and highlighted by ICREA. Each piece has something unique about it, whether it be a particularly elegant solution, the huge impact it has in the media or the sheer fascination it generates as a truly new idea. For whatever the reason, these are the best of the best and, as such, we are proud to share them here.
LIST OF SCIENTIFIC HIGHLIGHTS
Strong coupling of artificial atoms mediated by waveguide photons (2019)
Chang, Darrick (ICFO)view details
Malaria parasites have alternative pathways for sexual conversion (2019)
Cortés Closas, Alfred (ISGlobal)view details
The fundamental characteristics of the life cycle of malaria parasites were discovered over a century ago, but some specific steps are not well understood yet. One such step is the transition from asexual blood stages into sexual forms termed gametocytes, necessary for human to mosquito transmission. The results presented in this article modify the previous textbook view of this part of the malaria life cycle.
All malaria clinical symptoms in humans are produced by repeated cycles of exponential asexual parasite growth in the blood. However, transmission of the disease from one human to another via a mosquito vector requires that some of the asexual parasites convert into non-replicating sexual forms termed gametocytes. Gametocytes are the only malaria parasite stages able to infect mosquitoes. For many years, the widely accepted model was that at each cycle of asexual growth a small subset of the parasites commits to sexual conversion, and then they must go through an additional round of multiplication as sexually-committed forms before they actually convert into gametocytes. However, a detailed characterization of the process was previously not possible because molecular markers for sexually-committed forms were not available.
To address this gap of knowledge, we took advantage of our previous identification (in collaboration with other teams) of the PfAP2-G transcription factor as the master regulator of sexual conversion in malaria parasites. Using PfAP2-G as a marker for sexually committed parasites, we found that the additional round of multiplication after sexual commitment is not an obligate step. Thus, parasites can follow two alternative pathways after committing to sexual development: multiplying for one additional cycle before actual conversion into sexual forms (which we termed next cycle conversion route), or converting directly after commitment (same cycle conversion route). The availability of the two alternatives routes provides plasticity to the process, to either increase the output of sexual forms or ensure rapid conversion that may enable survival under harsh conditions.
Cells with double number of chromosomes can generate three cells during mouse embryo development. (2019)
Cosma, Maria Pia (CRG)view details
Cells with high ploidy content, i.e with increased number of chromosomes, are common in mammalian adult tissues. Cell-to-cell fusion generates polyploid cells during mammalian development and tissue regeneration. However, whether increased ploidy can be occasionally tolerated during embryogenesis still remains largely unknown. We showed that tetraploid cells, when injected in a recipient mouse embryo, can generate diploid cells upon tripolar mitosis reduction. The generated diploid cells include the correct number of chromosomes and form part of the adult tissues in mouse. Overall, we discovered an unexpected process of controlled genome reduction generating diploid cells during mouse embryo development.
Individuals' brain synchronization to speech relates to language learning capacities (2019)
de Diego Balaguer, Ruth (UB)view details
Humans are good at synchronizing body movements with sound, for instance, when we move our feet or the head to the rhythm of a song. This happens without trying, without having trained and it has even been proved in babies. Most of the current research on this field has focused on how body movements are encouraged by the rhythm of the music, but there is little known about how this synchronization works when it comes to speech. Aiming to focus on the link between motor rhythms and speech audio signals, we designed an apparently easy task: for a minute, participants had to listen to a rhythmical sequence of syllables and at the same time, they had to repeatedly whisper “tah”.
The analysis and results showed an unexpected pattern: population is divided into two groups. While some people spontaneously synchronize whispers with that sequence (good synchronizers), others did not experience any effect from the external rhythm (bad synchronizers). This effect is surprisingly strong and stable over time. Given such different patterns, we studied whether these variations had implications in the brain organization and behaviour. Results showed that good synchronizers have more white matter in those pathways connecting speech-perception areas (listening) with speech-production areas (speaking). In addition, the neural frequencies in brain areas related to speech motor planning of good synchronizers were more aligned with the syllable rhythm than poor synchronizers. Importantly, all these characteristics were accompanied by better word learning abilities in good synchronisers that were able to segment and recognise new words embedded in fluent speech. The task used in this study could serve to characterize individual differences and promote language research.
This methodology can help finding effects that were hidden by grouping populations with different neural and behaviour attributes. Also, we think the use of this test could reinforce the early diagnostic of some pathologies (such as Alzheimer’s, Parkinson’s or Multiple Sclerosis) and help assessing the speech and cognitive development in kids.
Brain Songs and Awakening: Towards understanding consciousness, different brain states and disease recovery (2019)
Deco, Gustavo (UPF)view details
How quickly do we become conscious of signals in the environment? The study of Reference 1 significantly advances our understanding of the timescale activity of whole-brain dynamics. The new framework, poetically called brain songs, sheds new light on the whole-brain networks involved in broadcasting information at this fast timescale. As such it supports and extends current accounts of when information becomes consciously available in the human brain. More generally, brain songs could be used to understand why the timescale of conscious processing changes in some diseases and as such the new findings could have important implications for understanding changes in neuropsychiatric disease – and perhaps even the nature of consciousness”.
How to force the transition from one brain state to another, for example, from sleep to wakefulness? The study of Reference 2 provides a reliable and robust definition that characterizes brain states and which, in combination with the complete computational model of the human brain, allows the systematic study of the effects of brain stimulation in the transition from one brain state to another. The study results demonstrate the usefulness of the model for discovering where to stimulate in order to force the transition between brain states. Applied to psychiatric diseases, this method may enhance recovery from the disease.
The Talmud in Latin: First Edition (2019)
Fidora Riera, Alexander (UAB)view details
In February 2019, the ERC project LATTAL, directed by A. Fidora, published the first edition ever of the so-called "Extractiones de Talmud", that is, the Latin translation of large parts of the Babylonian Talmud which was produced as part of an inquisitorial process against the Jews in Paris in 1245. The edition, which was prepared by a group of scholars headed by Ulisse Cecini and Óscar de la Cruz at the UAB, represents a major qualitative leap in the study of Christian-Jewish relations during the Middle Ages as well as for the study of the Hebrew/Aramaic Talmud. Moreover, bringing to light the "Extractiones", which were never meant to reach out to the general public, is a paramount example of the effectiveness of the historical humanities to overcome persecution and censorship whenever and wherever they occur.