Digital Simulation of Projective Non-Abelian Anyons with 68 Superconducting Qubits

Non-Abelian anyons are exotic quasiparticle excitations hosted by certain topological phases of matter.They break the fermion-boson dichotomy and obey non-Abelian braiding statistics:their interchanges yield unitary operations,rather than merely a phase factor,in a space spanned by topologically degenerate wavefunctions.They are the building blocks of topological quantum computing.However,experimental observation of non-Abelian anyons and their characterizing braiding statistics is notoriously challenging and has remained elusive hitherto,in spite of various theoretical proposals.Here,we report an experimental quantum digital simulation of projective non-Abelian anyons and their braiding statistics with up to 68 programmable superconducting qubits arranged on a two-dimensional lattice.By implementing the ground states of the toric-code model with twists through quantum circuits,we demonstrate that twists exchange electric and magnetic charges and behave as a particular type of non-Abelian anyons,i.e.,the Ising anyons.In particular,we show experimentally that these twists follow the fusion rules and non-Abelian braiding statistics of the Ising type,and can be explored to encode topological logical qubits.Furthermore,we demonstrate how to implement both single-and two-qubit logic gates through applying a sequence of elementary Pauli gates on the underlying physical qubits.Our results demonstrate a versatile quantum digital approach for simulating non-Abelian anyons,offering a new lens into the study of such peculiar quasiparticles.

Near-resonance enhanced label-free stimulated Raman scattering microscopy with spatial resolution near 130 nm

High-resolution optical microscopes that can break 180 nm in spatial resolution set to conventional microscopies are much-needed tools.However,current optical microscopes have to rely on exogenous fluorescent labels to achieve high resolution in biological imaging.Herein,we report near-resonance enhanced label-free stimulated Raman scattering(SRS)microscopy with a lateral resolution near 130 nm,in which the high-resolution image contrast originates directly from a low concentration of endogenous biomolecules,with sensitivity gains of approximately 23 times.Moreover,by using a 0.3-m-long optical fiber,we developed hyperspectral SRS microscopy based on spectral focusing technology.Attributed to enhancements in spatial resolution and sensitivity,we demonstrated highresolution imaging of three-dimensional structures in single cells and high-resolution mapping of large-scale intact mouse brain tissues in situ.By using enhanced high-resolution hyperspectral SRS,we chemically observed sphingomyelin distributed in the myelin sheath that insulates single axons.Our concept opens the door to biomedical imaging with~130 nm resolution.

Consistent apparent Young’s modulus of human embryonic stem cells and derived cell types stabilized by substrate stiffness regulation promotes lineage specificity maintenance

Background:Apparent Young’s modulus(AYM),which reflects the fundamental mechanical property of live cells measured by atomic force microscopy and is determined by substrate stiffness regulated cytoskeletal organization,has been investigated as potential indicators of cell fate in specific cell types.However,applying biophysical cues,such as modulating the substrate stiffness,to regulate AYM and thereby reflect and/or control stem cell lineage specificity for downstream applications,remains a primary challenge during in vitro stem cell expansion.Moreover,substrate stiffness could modulate cell heterogeneity in the single-cell stage and contribute to cell fate regulation,yet the indicative link between AYM and cell fate determination during in vitro dynamic cell expansion(from single-cell stage to multi-cell stage)has not been established.Results:Here,we show that the AYM of cells changed dynamically during passaging and proliferation on substrates with different stiffness.Moreover,the same change in substrate stiffness caused different patterns of AYM change in epithelial and mesenchymal cell types.Embryonic stem cells and their derived progenitor cells exhibited distinguishing AYM changes in response to different substrate stiffness that had significant effects on their maintenance of pluripotency and/or lineage-specific characteristics.On substrates that were too rigid or too soft,fluctuations in AYM occurred during cell passaging and proliferation that led to a loss in lineage specificity.On a substrate with‘optimal’stiffness(i.e.,3.5 kPa),the AYM was maintained at a constant level that was consistent with the parental cells during passaging and proliferation and led to preservation of lineage specificity.The effects of substrate stiffness on AYM and downstream cell fate were correlated with intracellular cytoskeletal organization and nuclear/cytoplasmic localization of YAP.Conclusions:In summary,this study suggests that optimal substrate stiffness regulated consistent AYM during passaging and proliferation reflects and contributes to hESCs and their derived progenitor cells lineage specificity maintenance,through the underlying mechanistic pathways of stiffness-induced cytoskeletal organization and the downstream YAP signaling.These findings highlighted the potential of AYM as an indicator to select suitable substrate stiffness for stem cell specificity maintenance during in vitro expansion for regenerative applications.