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1. Microscopic Model for Fractional Quantum Hall Nematics

   https://doi.org/10.1103/PhysRevLett.132.236503  

   Pu, Songyang; Balram, Ajit C; Taylor, Joseph; Fradkin, Eduardo; Papić, Zlatko (June 2024, Physical Review Letters)

   Geometric fluctuations of the density mode in a fractional quantum Hall (FQH) state can give rise to a nematic FQH phase, a topological state with a spontaneously broken rotational symmetry. While experiments on FQH states in the second Landau level have reported signatures of putative FQH nematics in anisotropic transport, a realistic model for this state has been lacking. We show that the standard model of particles in the lowest Landau level interacting via the Coulomb potential realizes the FQH nematic transition, which is reached by a progressive reduction of the strength of the shortest-range Haldane pseudopotential. Using exact diagonalization and variational wave functions, we demonstrate that the FQH nematic transition occurs when the system’s neutral gap closes in the long-wavelength limit while the charge gap remains open. We confirm the symmetry-breaking nature of the transition by demonstrating the existence of a “circular moat” potential in the manifold of states with broken rotational symmetry, while its geometric character is revealed through the strong fluctuations of the nematic susceptibility and Hall viscosity. Published by the American Physical Society2024 

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2. Deterministic Generation of Qudit Photonic Graph States from Quantum Emitters

   https://doi.org/10.1103/PRXQuantum.5.020346  

   Raissi, Zahra; Barnes, Edwin; Economou, Sophia E (May 2024, PRX Quantum)

   We propose and analyze deterministic protocols to generate qudit photonic graph states from quantum emitters. We show that our approach can be applied to generate any qudit graph state and we exemplify it by constructing protocols to generate one- and two-dimensional qudit cluster states, absolutely maximally entangled states, and logical states of quantum error-correcting codes. Some of these protocols make use of time-delayed feedback, while others do not. The only additional resource requirement compared to the qubit case is the ability to control multilevel emitters. These results significantly broaden the range of multiphoton entangled states that can be produced deterministically from quantum emitters. Published by the American Physical Society2024 

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3. Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene

   https://doi.org/10.1103/PhysRevX.15.011045  

   Waters, Dacen; Okounkova, Anna; Su, Ruiheng; Zhou, Boran; Yao, Jiang; Watanabe, Kenji; Taniguchi, Takashi; Xu, Xiaodong; Zhang, Ya-Hui; Folk, Joshua; et al (February 2025, Physical Review X)

   The advent of moiré platforms for engineered quantum matter has led to discoveries of integer and fractional quantum anomalous Hall effects, with predictions for correlation-driven topological states based on electron crystallization. Here, we report an array of trivial and topological insulators formed in a moiré lattice of rhomobohedral pentalayer graphene (R5G). At a doping of one electron per moiré unit cell ( $\nu =1$), we see a correlated insulator with a Chern number that can be tuned between $C=0$and $+1$by an electric displacement field. This is accompanied by a series of additional Chern insulators with $C=+1$originating from fractional fillings of the moiré lattice— $\nu =1/4$, $1/3$, and $2/3$—associated with the formation of moiré-driven topological electronic crystals. At $\nu =2/3$the system exhibits an integer quantum anomalous Hall effect at zero magnetic field, but further develops hints of an incipient $C=2/3$fractional Chern insulator in a modest field. Our results establish moiré R5G as a fertile platform for studying the competition and potential intertwining of integer and fractional Chern insulators. Published by the American Physical Society2025 

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4. Testing the Renormalization of the von Klitzing Constant by Cavity Vacuum Fields

   https://doi.org/10.1103/PhysRevX.14.021038  

   Enkner, Josefine; Graziotto, Lorenzo; Appugliese, Felice; Rokaj, Vasil; Wang, Jie; Ruggenthaler, Michael; Reichl, Christian; Wegscheider, Werner; Rubio, Angel; Faist, Jérôme (June 2024, Physical Review X)

   The value of fundamental physical constants is affected by the coupling of matter to the electromagnetic vacuum state, as predicted and explained by quantum electrodynamics. In this work, we present a millikelvin magnetotransport experiment in the quantum Hall regime that assesses the possibility of the von Klitzing constant being modified by strong cavity vacuum fields. By employing a Wheatstone bridge, we measure the difference between the quantized Hall resistance of a cavity-embedded Hall bar and the resistance standard, achieving an accuracy down to one part in ${10}^5$for the lowest Landau level. While our results do not suggest any deviation that could imply a modified Hall resistance, our work represents pioneering efforts in exploring the fundamental implications of vacuum fields in solid-state systems. Published by the American Physical Society2024 

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5. Evidence for nonzero electron velocity at the tunnel exit in strong-field atomic ionization

   https://doi.org/10.1103/PhysRevResearch.6.023049  

   Ivanov, I A; Kheifets, A S; Schimmoller, A; Landsman, A S; Kim, Kyung Taec (April 2024, Physical Review Research)

   We provide some evidence for nonzero electron velocity at the tunnel exit in strong-field atomic ionization. Our investigation is based on the analysis of a suitably chosen correlation function which describes correlations between the two observables: the longitudinal electron velocity and the appearance of the photoelectron in the continuum at the end of the laser pulse. The results of the correlation function analysis that we perform are confirmed by the calculations using the quantum orbits method. Published by the American Physical Society2024 

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