arXiv subjects

Xujing Liu

Publications and source records attributed to Xujing Liu.

5 recordsLinked to original sources

arXiv2026

Integrated nanophotonic platform for on-chip quantum emitter interactions and entanglement

Entanglement between solid-state quantum emitters (QEs) is a key resource for photonic quantum technologies. Achieving such entanglement requires strong and controllable long-range interactions between QEs. However, engineering such coupling remains challenging, particularly for on-chip distant solid-state QEs. Here, we introduce a forward-designed platform that enables ultracompact nanophotonic architectures to mediate enhanced long-range QE-QE interactions via engineered surface plasmon polariton interference. Using this strategy, we realize two distinct configurations: a phase-conjugated elliptic design for energy funneling, and a co-radiating hyperbolic design for its suppression. We experimentally demonstrate large enhancement and suppression of energy transfer rates compared to bare substrates. Furthermore, we predict transient entanglement between spatially separated QEs with concurrence peaking at 0.493, approaching the theoretical bound in the transient regime. Extending to the multi-QE case, we observe enhanced energy funneling and predict QE-QE entanglement in three-QE configurations. These results establish a compact and scalable framework for on-chip entanglement engineering in integrated quantum nanophotonic systems.

cond-mat.mes-hall↗

arXiv2026

Chip-integrated metasurface-enabled single-photon skyrmion sources

Skyrmions, topologically stable field configurations, have recently emerged in classical optics as structured light for high-density data applications. Achieving controllable on-chip generation of single-photon skyrmions, while being highly desirable for quantum information technologies, remains challenging due to the nanoscale confinement of quantum emitters (QEs). Here we demonstrate a metasurface-integrated quantum emitter (metaQE) platform enabling room-temperature on-chip generation of single-photon skyrmions. Near-field coupling between QEs and propitiously designed surface arrays of meta-atoms mediates spin-orbit interaction, transforming nanoscale-localized dipole emission into free-propagating topologically structured photonic modes. By exploiting this approach for structuring quantum emission from different color centers in nanodiamonds, we realize diverse skyrmionic states, including high-order anti-skyrmions and skyrmionium, and thereby demonstrate its universality across QEs. Our work establishes a unified framework for on-chip structured quantum light sources, offering versatile control of high-dimensional topological states, such as skyrmions, and advancing scalable quantum photonic technologies.

physics.optics↗

arXiv2025

Integrated angstrom-tunable polarization-resolved solid-state photon sources

The development of high-quality solid-state photon sources is essential to nano optics, quantum photonics, and related fields. A key objective of this research area is to develop tunable photon sources that not only enhance the performance but also offer dynamic functionalities. However, the realization of compact and robust photon sources with precise and wide range tunability remains a long-standing challenge. Moreover, the lack of an effective approach to integrate nanoscale photon sources with dynamic systems has hindered tunability beyond mere spectral adjustments, such as simultaneous polarization control. Here we propose a platform based on quantum emitter (QE) embedded metasurfaces (QEMS) integrated with a microelectromechanical system (MEMS)-positioned microcavity, enabling on-chip multi-degree control of solid-state photon sources. Taking advantages of MEMS-QEMS, we show that typically broadband room-temperature emission from nanodiamonds containing nitrogen-vacancy centres can be narrowed to 3.7 nm and dynamically tuned with angstrom resolution. Furthermore, we design a wavelength-polarization-multiplexed QEMS and demonstrate polarization-resolved control of the MEMS-QEMS emission in a wide wavelength range (650 nm to 700 nm) along with polarization switching at sub-millisecond timescales. We believe that the proposed MEMS-QEMS platform can be adapted for most existing QEs, significantly expanding their room-temperature capabilities and thereby enhancing their potential for advanced photonic applications.

physics.optics↗

arXiv2023

Ultracompact single-photon sources of linearly polarized vortex beams

Ultracompact chip-integrated single-photon sources of collimated beams with polarizationencoded states are crucial for integrated quantum technologies. However, most of currently available single-photon sources rely on external bulky optical components to shape the polarization and phase front of emitted photon beams. Efficient integration of quantum emitters with beam shaping and polarization encoding functionalities remains so far elusive. Here, we present ultracompact single-photon sources of linearly polarized vortex beams based on chip-integrated quantum emitter-coupled metasurfaces, which are meticulously designed by fully exploiting the potential of nanobrick arrayed metasurfaces. We first demonstrate on-chip single-photon generation of high-purity linearly polarized vortex beams with prescribed topological charges of -1, 0, and +1. We further realize multiplexing of single-photon emission channels with orthogonal linear polarizations carrying different topological charges and demonstrate their entanglement. Our work illustrates the potential and feasibility of ultracompact quantum emitter-coupled metasurfaces as a new quantum optics platform for realizing chip-integrated high-dimensional single-photon sources.

physics.optics↗

arXiv2023

Single-photon circularly polarized single-mode vortex beams

Generation of single photons carrying spin and orbital angular momenta (SAM and OAM) opens enticing perspectives for exploiting multiple degrees of freedom for high-dimensional quantum systems. However, on-chip generation of single photons encoded with single-mode SAM-OAM states has been a major challenge. Here, by utilizing carefully designed anisotropic nanodimers fabricated atop a substrate, supporting surface plasmon polariton (SPP) propagation, and accurately positioned around a quantum emitter (QE), we enable nonradiative QE-SPP coupling and the SPP outcoupling into free-space propagating radiation featuring the designed SAM and OAM. We demonstrate on-chip room-temperature generation of well-collimated (divergence < 7.5 degrees) circularly polarized (chirality > 0.97) single-mode vortex beams with different topological charges (l = 0, 1, and 2) and high single-photon purity, g(0) < 0.15. The developed approach can straightforwardly be extended to produce multiple, differently polarized, single-mode single-photon radiation channels, and enable thereby realization of high-dimensional quantum sources for advanced quantum photonic technologies.

physics.optics↗