CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B leads to disruption of neural cell differentiation from NT2 cells

The human neuron-specific gene, GPM6B (Glycoprotein membrane 6B), is considered a key gene in neural cell functionality. This gene contains an exceptionally long and strictly monomorphic short tandem repeat (STR) of 9-repeats, (GA)9. STRs in regulatory regions, may impact on the expression of nearby genes. We used CRISPR-based tool to delete this GA-repeat in NT2 cells, and analyzed the consequence of this deletion on GPM6B expression. Subsequently, the edited cells were induced to differentiate into neural cells, using retinoic acid (RA) treatment. Deletion of the GA-repeat significantly decreased the expression of GPM6B at the RNA (p < 0.05) and protein (40%) levels. Compared to the control cells, the edited cells showed dramatic decrease of the astrocyte and neural cell markers, including GFAP (0.77-fold), TUBB3 (0.57-fold), and MAP2 (0.2-fold). Subsequent sorting of the edited cells showed an increased number of NES (p < 0.01), but a decreased number of GFAP (p < 0.001), TUBB3 (p < 0.05), and MAP2 (p < 0.01), compared to the control cells. In conclusion, CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B, led to decreased expression of this gene, which in turn, disrupted differentiation of NT2 cells into neural cells.Publisher PDFPeer reviewe

Ultralong temporal coherence in optically trapped exciton-polariton condensates

Funding: This work was supported by Grant No. EPSRC EP/S014403/1. K.O. acknowledges EPSRC for PhD studentship support through grant no. EP/L015110/1. P.S. acknowledges support by Westlake University (Project No. 041020100118), Program 2018R01002 supported by Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang, and bilateral Greece-Russia Polisimulator project co-financed by Greece and the EU Regional Development Fund.We investigate an optically trapped exciton-polariton condensate and observe temporal coherence beyond 1 ns in duration. Due to the reduction of the spatial overlap with the thermal reservoir of excitons, the coherence time of the trapped condensate is more than an order of magnitude longer than that of an untrapped condensate. This ultralong coherence enables high-precision spectroscopy of the trapped condensate, and we observe periodic beats of the field correlation function due to a fine energy splitting of two polarization modes of the condensate. Our results are important for realizing polariton simulators with spinor condensates in lattice potentials.PostprintPeer reviewe

Local tuning of Rydberg exciton energies in nanofabricated Cu2O pillars

Funding: This work was supported by the EPSRC through grant No. EP/S014403/1, by The Royal Society through RGS\R2\192174, and by the Leverhulme Trust through grant No. RPG-2022-188. A.S.P. acknowledges the PhD scholarship from University of St Andrews and Macquarie University and the support of Sydney Quantum Academy, Sydney, NSW, Australia for The SQA Supplementary Scholarship. S.K.R. acknowledges the Carnegie Trust for the Universities of Scotland Research Incentive Grant RIG009823. T.V. acknowledges support through the ARC Centre of Excellence for Engineered Quantum Systems (CE170100009). The authors acknowledge the support of EPSRC Capital for Great Technologies Grant EP/L017008/1 and the EPSRC Strategic Equipment Resource Grant EP/R023751/1 for the use of the FIB equipment for the fabrication of the pillars.Rydberg excitons in Cu2O feature giant optical nonlinearities. To exploit these nonlinearities for quantum applications, the confinement must match the Rydberg blockade size, which in Cu2O could be as large as a few microns. Here, in a top-down approach, we show how exciton confinement can be realised by focused-ion-beam etching of a polished bulk Cu2O crystal without noticeable degradation of the excitonic properties. The etching of the crystal to micron sizes allows for tuning the energies of Rydberg excitons locally, and precisely, by optically induced temperature change. These results pave the way for exploiting the large nonlinearities of Rydberg excitons in micropillars for making non-classical light sources, while the precise tuning of their emission energy opens up a viable pathway for realizing a scalable photonic quantum simulation platform.Peer reviewe

Crossover from exciton-polariton to photon Bose-Einstein condensation

BEC of exciton-polaritons and related effects such as superfluidity1,2, spontaneous symmetry breaking3,4 and quantised vortices5,6 open way to creation of novel light sources7 and optical logic elements8. Remarkable observations of exciton-polariton BEC in microcavities9-12 have been reported in the recent ten years. Very recently, thermalisation and subsequent condensation of cavity photons in a dye-filled microcavity have been observed13. Here we show that BEC of both exciton-polaritons and photons can be created in the same system under different optical excitation conditions. A dynamic phase transition between a photon and a polariton BEC takes place after a single high-power excitation pulse and we find both condensed states in thermal equilibrium with the excited states. At the crossover, photons and polaritons coexist, which results in a decrease in the long-range spatial coherence. Build-up and successive depinning of polarisation is observed at the threshold of both polariton and photon condensation

Highly-excited Rydberg excitons in synthetic thin-film cuprous oxide

S.S. acknowledges support from the Swedish Research Council (Starting Grant No. 2019-04821) and from the Göran Gustafsson Foundation. H.A. acknowledges the Purdue University Startup fund, the financial support from the Industry-University Cooperative Research Center Program at the US National Science Foundation under Grant No. 2224960, and the AirForce Office of Scientific Research under award number FA9550-23-1-0489.Cuprous oxide (Cu2O) has recently emerged as a promising material in solid-state quantum technology, specifically for its excitonic Rydberg states characterized by large principal quantum numbers (n). The significant wavefunction size of these highly-excited states (proportional to n2) enables strong long-range dipole-dipole (proportional to n4) and van der Waals interactions (proportional to n11). Currently, the highest-lying Rydberg states are found in naturally occurring Cu2O. However, for technological applications, the ability to grow high-quality synthetic samples is essential. The fabrication of thin-film Cu2O samples is of particular interest as they hold potential for observing extreme single-photon nonlinearities through the Rydberg blockade. Nevertheless, due to the susceptibility of high-lying states to charged impurities, growing synthetic samples of sufficient quality poses a substantial challenge. This study successfully demonstrates the CMOS-compatible synthesis of a Cu2O thin film on a transparent substrate that showcases Rydberg excitons up to n=8 which is readily suitable for photonic device fabrications. These findings mark a significant advancement towards the realization of scalable and on-chip integrable Rydberg quantum technologies.Publisher PDFPeer reviewe

Quantum confined Rydberg excitons in Cu2O nanoparticles

Funding: UK EPSRC Grant No. EP/S014403/1 and The Royal Society RGS\R2\192174. K.O. acknowledges EPSRC for PhD studentship support through grant no. EP/L015110/1. S.K.R. acknowledges the Carnegie Trust for the Research Incentive Grant RIG009823.The quantum confinement of Rydberg excitons is an important step towards exploiting their large nonlinearities for quantum applications. We observe Rydberg excitons in natural nanoparticles of Cu2O. We resolve up to the principal quantum number n=12 in a bulk Cu2O crystal and up to n=6 in nanoparticles extracted from the same crystal. The exciton transitions in nanoparticles are broadened and their oscillator strengths decrease as ∝n−4 compared to those in the bulk (decreasing as ∝n−3). We explain our results by including the effect of quantum confinement of exciton states in the nanoparticles. Our results provide an understanding of the physics of Cu2O Rydberg excitons in confined dimensions.Publisher PDFPeer reviewe

Spontaneous symmetry breaking in a polariton and photon laser

We report on the simultaneous observation of spontaneous symmetry breaking and long-range spatial coherence both in the strong and the weak-coupling regime in a semiconductor microcavity. Under pulsed excitation, the formation of a stochastic order parameter is observed in polariton and photon lasing regimes. Single-shot measurements of the Stokes vector of the emission exhibit the buildup of stochastic polarization. Below threshold, the polarization noise does not exceed 10%, while above threshold we observe a total polarization of up to 50% after each excitation pulse, while the polarization averaged over the ensemble of pulses remains nearly zero. In both polariton and photon lasing regimes, the stochastic polarization buildup is accompanied by the buildup of spatial coherence. We find that the Landau criterion of spontaneous symmetry breaking and Penrose-Onsager criterion of long-range order for Bose-Einstein condensation are met in both polariton and photon lasing regimes.Comment: 5 pages, 3 figure