Alexey Belyanin

Vacuum nanoelectronic-based photodetectors operating via photoassisted field emission have the potential for significantly improved performance and robust operation under high-temperature and high-radiation environments. Here we demonstrate on-chip, GaN-based UV lateral nanogap field-emission photodiodes (NFEPs) with bandgap-dependent ultrahigh responsivity up to 2.21 × 107 A/W and corresponding detectivity of 5.0 × 1014 cm Hz1/2 W–1. The high performance is proposed to occur by a surface photovoltage effect that dramatically lowers the barrier for field emission across the nanogap upon above-bandgap illumination. These results show promise toward a new class of integrated and high-performance, bandgap-tunable, deep-UV photodetectors operable in harsh environments.

Entangled photons provide non‐classical correlations that enable measurement sensitivities beyond classical limits, scalable fault‐tolerant quantum computation, and fundamentally secure quantum communication, making them a foundational necessity for next‐generation quantum technologies. Here we propose and analyze a novel source of entangled photons based on ScAlN/GaN quantum wells integrated with dielectric metasurfaces. Giant second‐order intersubband nonlinearity of the GaN quantum wells with strain‐compensated delta‐doped ScAlN barriers caused by strong built‐in electric fields combined with superior mode‐coupling performance of metasurfaces optimized by inverse design give rise to efficient parametric down‐conversion and generation of entangled photons in the telecom range. We develop a rigorous Heisenberg–Langevin formalism which includes field quantization, dissipation and fluctuations for all fields, parametric amplification of thermal noise and zero‐point fluctuations, and other relevant effects. Our proposed approach of employing the emergent photonic material ScAlN promises high biphoton generation rate over from a compact integrated structure that is only 0.5 thick while mitigating strain‐related issues that have so far impeded progress of nitride‐based heterostructures for quantum photonic applications into the infrared and visible wavelengths. Our result therefore is relevant for numerous applications ranging from quantum sensing, quantum information, and computing.

We study fermionic and bosonic systems coupled to a real or synthetic static gauge field that is quantized, so the field itself is a quantum degree of freedom and can exist in coherent superposition. A natural source of a quantized magnetic flux (QMF) could be a superconducting current loop. We show that coupling to a common QMF gives rise to an emergent all-to-all interaction between particles with no classical analog, as it is topological and nonlocal (independent of interparticle distance). Moreover, the interaction persists via a quantized Aharonov-Bohm effect even when the particles lie in a nominally field-free region. The QMF mediates exchange of angular momenta between particles, and it gives rise to quantum phase transitions in both one- and two-dimensional systems, resulting in the spontaneous appearance of the chiral current and magnetic polarization. Many other interesting phenomena can be realized in this class of systems, for example, the noninteger Chern number when the magnetic flux exists in the quantum superposition of different flux states, or the nonlocal electron blockade. We show that similar physics can be realized in synthetic systems with artificial QMF, with the advantage of tunability enabling much higher strength of the synthetic QMF and the interaction of neutral particles.

We present a minimal, tunable many-body system of fermions coupled to quantum magnetic flux. The model is analytically diagonalizable and exhibits collective many-body phenomena, including an orbital Stoner instability and a Dicke-like quantum phase transition. The many-body interactions are mediated by zero-point fluctuations of a quantized magnetic flux whose oscillator mode remains in its ground state. In contrast to standard cavity quantum electrodynamics, where the dominant coupling is the electric-dipole coupling between matter and electric-field operators, here the quantized magnetic field of an LC resonator couples to the orbital angular momentum of the particles. Because the transition is driven by an orbital-current sector and the diamagnetic term is retained explicitly, the instability is not a conventional electric-dipole Dicke soft-mode transition. Adding a Josephson junction (JJ) to the linear LC circuit allows us to explore nonlinear flux-matter phases and sector-selective photon dressing in regimes relevant to circuit QED and mesoscopic rings. Furthermore, we consider tight-binding systems that exhibit a tunable nonlinearity representing a synthetic JJ without including an actual JJ in the circuit.

The emerging field of cavity quantum materials seeks to control electronic phases using the quantum fluctuations of confined electromagnetic fields. Most existing approaches rely on electric-dipole, density-like couplings, for which strong equilibrium effects in solids remain difficult to obtain. Here we propose a different route, in which the ground state of an electron system is controlled or modified via coupling to the vacuum fluctuations of the quantized magnetic flux of a superconducting LC circuit. The resulting long-range attractive interactions between electron angular momentum states induce unconventional chiral superconductivity in a broad class of materials, with critical temperatures of a few Kelvin or even higher, depending on the area covered by the field. The magnetic flux of an LC circuit remains in the ground state, and all of its parameters can be controlled to optimize a particular pairing regime. The results identify circuit quantum magnetostatics as a highly tunable platform for engineering electron interactions and creating new quantum phases of matter.

We present a new class of pseudocyanine iodide (PIC-I) aggregates formed by freeze-induced self-assembly into layered ribbon structures. Unlike conventional PIC J-aggregates with head-to-tail dipole alignment, these ribbons adopt a complex and mixed HJ-aggregate arrangement. Unexpectedly, the aggregate ribbons exhibit intense, red-shifted fluorescence, in contrast to the typical nonemissive nature of their monomer form. At 4 K, their emission lifetimes range from ∼300 ps to ∼1 ns, substantially longer than those of J-aggregates. The combination of red-shifted emission, monomer-like absorption, and extended lifetimes reveals their mixed packing contributions. Second-order autocorrelation measurements with a Hanbury Brown and Twiss interferometer show photon bunching, providing evidence for cooperative emission from collective excitonic states─an effect not previously observed in any aggregates larger than dimers. These findings establish PIC-I HJ-aggregate ribbons as a unique platform for exploring collective photophysics in mixed aggregate molecular assemblies, suggesting potential applications in bioimaging, light-emitting devices, and sensing.

Cooperative emission of photons from an ensemble of quantum dots (QDs) as superradiance can arise from the electronically coupled QDs with a coherent emitting excited state. This contrasts with superfluorescence (Dicke superradiance), where the cooperative photon emission requires a buildup of coherence in an ensemble of incoherently excited QDs via their coupling to a common radiation mode. In perovskite QDs, superradiance has been rarely observed, unlike superfluorescence, due to the challenge in QD electronic coupling. Here, we report superradiance with a very narrow linewidth (3 QD superlattice achieved through the combination of quantum confinement and ligand engineering. The superradiance is polarized in contrast to the uncoupled exciton emission from the same superlattice, indicating anisotropic electronic coupling in superlattices. This finding suggests the potential of a perovskite QD superlattice with structurally controllable interdot coupling as the polarized cooperative photon emitters.

We present a general formalism and specific implementations of quantum gates based on interaction of single photons with open dissipative nanocavities containing ensembles of quantum emitters. Rich dynamics of entangled bright and dark states of quantum emitters coupled to a nanocavity field gives rise to efficient manipulation of the quantum state of an incident photon. As a simple example, we analyze the realization of a controlled-NOT gate in which the cavity loaded with quantum emitters serves as a control qubit whereas the polarization state of an incident photon is a flying target qubit.

The growing number of high school students who receive physics instruction from out-of-field teachers with an insufficient background in physics has been a seri The growing number of high school students who receive physics instruction from out-of-field teachers with an insufficient background in physics has been a seri