arXiv subjects

Jin-Dong Song

Publications and source records attributed to Jin-Dong Song.

8 recordsLinked to original sources

arXiv2026

Polarization-Aligned, Spectrally Consistent Quantum Emitters in As-Exfoliated Carbon-Doped Hexagonal Boron Nitride

Solid-state quantum emitters constitute an essential building blocks of integrated quantum photonic circuits. Among potential emitter platforms, hexagonal boron nitride (hBN) hosts single-photon emitters in an atomically thin lattice amenable to photonic integration. However, multi-step fabrication approaches, limited defect specificity, and poor emission wavelength repeatability limit the performance of hBN quantum light sources relative to established solid-state architectures. Developing methods to induce emitters that are both suitable for planar photonic devices and that exhibit consistent optical properties remains a key objective. In this work, we identify quantum emitters in as-exfoliated carbon-doped hBN that exhibit both stable and repeatable emission energies together with polarization-aligned dipoles. Owing to the high lattice crystallinity, these single-photon light sources demonstrate exceptional spectral stability with a standard deviation of 7 $μ$eV. The emission energy is reproducible and confined within a narrow range of 2.2825 ${\pm}$ 0.0042 eV. Notably, consistent dipole alignment for absorption and emission polarization suggests that the intrinsic defects are of the same nature. The color centers are observed in as-exfoliated hBN without any post-treatment, significantly facilitating further interfacing with planar photonic structures. These reproducible, polarization-aligned quantum emitters in as-exfoliated hBN provide a versatile platform for scalable integration, offering a pathway toward a broad range of quantum technologies.

cond-mat.mes-hall↗

arXiv2025

Deterministic nanofabrication of quantum dot-circular Bragg grating resonators with high process yield using in-situ electron beam lithography

The controlled integration of quantum dots (QDs) as single-photon emitters into quantum light sources is essential for the implementation of large-scale quantum networks. In this study, we employ the deterministic in-situ electron-beam lithography (iEBL) nanotechnology platform to integrate individual QDs with high accuracy and process yield into circular Bragg grating (CBG) resonators. Notably, CBG devices comprising just 3 to 4 rings exhibit photon extraction efficiencies comparable to those of structures with more rings. This facilitates faster fabrication, reduces the device footprint, and enables compatibility with electrical contacting. To demonstrate the scalability of this process, we present results of 95 optically active QD-CBG devices fabricated across two lithography sessions. These devices exhibit bright, narrow-linewidth single-photon emission with excellent optical quality. To evaluate QD placement accuracy, we apply a powerful characterization technique that combines cathodoluminescence (CL) mapping and scanning electron microscopy. Statistical analysis of these devices reveals that our iEBL approach enables high alignment accuracy and a process yield of over >90% across various CBG geometries. Our findings highlight a reliable route toward the scalable fabrication of high-performance QD-based single-photon sources for use in photonic quantum technology applications.

cond-mat.mes-hall↗

arXiv2025

Multimode Nanobeam Photonic Crystal Cavities for Purcell Enhanced Quantum Dot Emission

Epitaxial III-V semiconductor quantum dots in nanopthonic structures are promising candidates for implementing on-demand indistinguishable single-photon emission in integrated quantum photonic circuits. Quantum dot proximity to the etched sidewalls of hosting nanophotonic structures, however, has been shown to induce linewidth broadening of excitonic transitions, which limits emitted single-photon indistinguishability. Here, we design and demonstrate GaAs photonic crystal nanobeam cavities that maximize quantum dot distances to etched sidewalls beyond an empirically determined minimum that curtails spectral broadening. Although such geometric constraint necessarily leads to multimode propagation in nanobeams, which significantly complicates high quality factor cavity design, we achieve resonances with quality factors $Q\approx10^3$, which offer the potential for achieving Purcell radiative rate enhancements $F_p\approx100$.

physics.optics↗

arXiv2025

On-demand storage and retrieval of single photons from a semiconductor quantum dot in a room-temperature atomic vapor memory

Interfacing light from solid-state single-photon sources with scalable and robust room-temperature quantum memories has been a long-standing challenge in photonic quantum information technologies due to inherent noise processes and time-scale mismatches between the operating conditions of solid-state and atomic systems. Here, we demonstrate on-demand storage and retrieval of single photons from a semiconductor quantum dot device in a room-temperature atomic vapor memory. A deterministically fabricated InGaAs quantum dot light source emits single photons at the wavelength of the cesium D1 line at 895\,nm which exhibit an inhomogeneously broadened linewidth of 5.1(7)\,GHz and are subsequently stored in a low-noise ladder-type cesium vapor memory. We show control over the interaction between the single photons and the atomic vapor, allowing for variable retrieval times of up to 19.8(3)\,ns at an internal efficiency of $η_\mathrm{int}=0.6(1)\%$. Our results significantly expand the application space of both room-temperature vapor memories and semiconductor quantum dots in future quantum network architectures.

quant-ph↗

arXiv2017

Deterministic integration of quantum dots into on-chip multi-mode interference beamsplitters using in-situ electron beam lithography

The development of multi-node quantum optical circuits has attracted great attention in recent years. In particular, interfacing quantum-light sources, gates and detectors on a single chip is highly desirable for the realization of large networks. In this context, fabrication techniques that enable the deterministic integration of pre-selected quantum-light emitters into nanophotonic elements play a key role when moving forward to circuits containing multiple emitters. Here, we present the deterministic integration of an InAs quantum dot into a 50/50 multi-mode interference beamsplitter via in-situ electron beam lithography. We demonstrate the combined emitter-gate interface functionality by measuring triggered single-photon emission on-chip with $g^{(2)}(0) = 0.13\pm 0.02$. Due to its high patterning resolution as well as spectral and spatial control, in-situ electron beam lithography allows for integration of pre-selected quantum emitters into complex photonic systems. Being a scalable single-step approach, it paves the way towards multi-node, fully integrated quantum photonic chips.

physics.app-ph↗

arXiv2017

Zero bias conductance peak in InAs nanowire coupled to superconducting electrodes

We report the occurrence of the zero-bias conductance peak (ZBCP) in an InAs nanowire coupled to PbIn superconductors with varying temperature, bias voltage, and magnetic field. The ZBCP is suppressed with increasing temperature and bias voltage above the Thouless energy of the nanowire. Applying a magnetic field also diminishes the ZBCP when the resultant magnetic flux reaches the magnetic flux quantum h/2e. Our observations are consistent with theoretical expectations of reflectionless tunneling, in which the phase coherence between an electron and its Andreev-reflected hole induces the ZBCP as long as time-reversal symmetry is preserved.

cond-mat.mes-hall↗

arXiv2012

Nexus between directionality of THz waves and structural parameters in groove-patterned InAs

We have performed terahertz (THz)-time domain spectroscopy in various geometries, for characterizing the directivity of THz waves emitted from groove-patterned InAs structures. First, we have distinguished the THz emission mechanisms as a function of epilayer thickness. The carrier drift was predominant in thin sample group (10-70 nm) which the electronic diffusion motion was overriding the oppositely aligned drifting dipoles in thick sample group (370-900 nm) as revealed via amplitude and phase variations. By combined use of the electron-beam lithography and the inductively coupled plasma etching in 1 μm-thick InAs epilayers, we have further fabricated either asymmetric V-groove patterns or symmetric parabolic patterns. The THz amplitude was enhanced, particularly along line-of-sight transmissive direction when the groove patterns act as microscale reflective mirrors periodically separated by a scale of diffusion length.

physics.optics↗

arXiv2012

Directional terahertz emission from diffusion-engineered InAs structures

We have designed and fabricated a new type of terahertz (THz) emitter that radiates THz waves along the surface-normal direction because of the lateral distributions of the transient electric dipoles. The excitation and measurements were performed using a conventional THz time-domain spectroscopy scheme with femtosecond optical pulses. The corrugated mirror patterns on the InAs layers made the radiation directional along the surface-normal direction, and the emission efficiency was controlled by adjustment of the pattern width.

physics.optics↗