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  • Bi-Josephson effect in a driven-dissipative supersolid
    The Josephson effect is a macroscopic quantum tunneling phenomenon in a system with superfluid property, when it is split into two parts by a barrier. Here, we examine the Josephson effect in a driven-dissipative supersolid realized by coupling Bose–Einstein condensates to an optical ring cavity. We show that the spontaneous breaking of spatial translation symmetry in supersolid makes the location of the splitting barrier have a significant influence on the Josephson effect. Remarkably, for the same splitting barrier, depending on its location, two different types of DC Josephson currents are found in the supersolid phase (compared to only one type found in the superfluid phase). Thus, we term it a bi-Josephson effect. We examine the Josephson relationships and critical Josephson currents in detail, revealing that the emergence of supersolid order affects these two types of DC Josephson currents differently—one is enhanced, while the other is suppressed. The findings of this work unveil unique Josephson physics in the supersolid phase, and show new opportunities to build novel Josephson devices with supersolids.

  • Beyond periodicity: tailoring Tamm resonances in plasmonic nanohole arrays for multimodal lasing
    Extraordinary optical transmission (EOT) through metal nanohole arrays (NHAs) and Tamm plasmon (TP) states have been investigated in plasmonic devices since 1998 and 2007, respectively. Since their introduction, various potential applications for structures that support these phenomena have been reported, including plasmonic absorbers, lasing cavities, and narrowband filters. The performance of EOT- and TP-based devices is significantly influenced by the sizes and patterns of the holes in the NHA. While the effects of hole size and shape on EOT have been extensively studied, similar research on TP structures involving metal NHAs is still lacking. Particularly, the impact of gradually introducing randomness into the metal NHA on TP modes has yet to be explored. In this work, we modify the hole sizes and arrangements of the metal NHA and examine the effects on EOT and Tamm resonances. We investigate three scenarios: the bare metal NHA, a passive Tamm resonant cavity, and a TP laser. We observe that multiple Tamm resonances appear as the periodicity of the holes increases. However, these resonances vanish when the hole arrangement shifts from a regular array to a pseudo-periodic random array, which is defined as a collection of holes placed randomly within a periodically repeating square unit cell. These multiple resonances can be attributed to the folding of dispersion lines in a periodically patterned TP cavity. The dispersion characteristics of the NHA array-based structures are calculated and analyzed to understand better the multiple resonances in the transmission and lasing emission patterns.

  • SU(N) magnetism with ultracold molecules
    Quantum systems with SU(N) symmetry are paradigmatic settings for quantum many-body physics. They have been studied for the insights they provide into complex materials and their ability to stabilize exotic ground states. Ultracold alkaline-earth atoms were predicted to exhibit SU(N) symmetry for , where I is the nuclear spin. Subsequent experiments have revealed rich many-body physics. However, alkaline-earth atoms realize this symmetry only for fermions with repulsive interactions. In this paper, we predict that ultracold molecules shielded from destructive collisions with static electric fields or microwaves exhibit SU(N) symmetry, which holds because deviations of the s-wave scattering length from the spin-free values are only about 3% for CaF with static-field shielding and are estimated to be even smaller for bialkali molecules. They open the door to N as large as 32 for bosons and 36 for fermions. They offer important features unachievable with atoms, including bosonic systems and attractive interactions.

  • Shared entanglement for three-party causal order guessing game
    In a variant of communication tasks, players cooperate in choosing their local strategies to compute a given task later, working separately. Utilizing quantum bits for communication and sharing entanglement between parties is a recognized method to enhance performance in these situations. In this work, we introduce the game for which three parties, Alice, Bob and Charlie, would like to discover the hidden order in which they make the moves. We show the advantage of quantum strategies that use shared entanglement and local operations over classical setups for discriminating operations’ composition order. The role of quantum resources improving the probability of successful discrimination is also investigated. Our research provides a basis for examining computational model featuring a specific gate set while examining the diverse operations achievable through permutations of its elements.

  • Spatio-temporal modeling and simulation of a mode-locked tapered semiconductor diode laser
    We present a theoretical model and numerical simulation results of the dynamics of a monolithic edge-emitting mode-locked tapered quantum well laser. The comprehensive simulation employs a dimensional traveling wave model and incorporates models for lateral current spreading and carrier diffusion, while also addressing thermal effects in the laser cavity. Our investigation of the pulse generation by passive mode-locking demonstrates good agreement with experimental observations. Furthermore, we perform a study of the intra-cavity propagation dynamics of the laser, which provides valuable insights for a better understanding of the laser’s behavior.