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Visible light active g- C 3 N 4(0.94) /CeO 2(0.05) /Fe 3 O 4(0.01) ternary composite nanosheets were fabricated by facile co-precipitation routes. The density functional theory (DFT) computations investigated changes in geometry and electronic character of g-C 3 N 4 with CeO 2 and Fe 3 O 4 addition. Chemical and surface characterizations were explored with XRD, XPS, SEM, TEM, PL, DRS and Raman measurements. DRS and PL spectroscopy evidenced the energy band gap tailoring from 2.68 eV for bulk g-C 3 N 4 and 2.92 eV for CeO 2 to 2.45 eV for the ternary nanocomposite. Efficient electron/hole pair separation, increase in red-ox species and high exploitation of solar spectrum due to band gap tailoring lead to higher degradation efficiency of g- C 3 N 4(0.94) /CeO 2(0.05) /Fe 3 O 4(0.01) . Superior sun light photocatalytic breakdown of 2-Chlorophenol was observed with g-C 3 N 4 having CeO 2 loading up to 5 wt%. In case of ternary nanocomposites deposition of 1 wt% Fe 3 O 4 over g-C 3 N 4 /CeO 2 binary composite not only showed increment in visible light catalysis as predicted by the DFT studies, but also facilitated magnetic recovery. The g- C 3 N 4(0.94) /CeO 2(0.05) /Fe 3 O 4(0.01) nanosheets showed complete mineralization of 25 mg.L −1 2-CP (aq) within 180 min exposure to visible portion of sun light and retained its high activity for 3 consecutive reuse cycles. The free radical scavenging showed superoxide ions and holes played a significant role compared to hydroxyl free radicals while chromatographic studies helped establish the 2-CP degradation mechanism. The kinetics investigations revealed 2.55 and 4.04 times increased rate of reactions compared to pristine Fe 3 O 4 and CeO 2 , showing highest rate constant value of 18.2 × 10 −3  min −1 for the ternary nanocomposite. We present very persuasive results that can be beneficial for exploration of further potential of g-C 3 N 4(0.94) /CeO 2(0.05) /Fe 3 O 4(0.01) in advance wastewater treatment systems.

Combining external control with long spin lifetime and coherence is a key challenge for solid state spin qubits. Tunnel coupling with electron Fermi reservoir provides robust charge state control in semiconductor quantum dots, but results in undesired relaxation of electron and nuclear spins through mechanisms that lack complete understanding. Here, we unravel the contributions of tunnelling-assisted and phonon-assisted spin relaxation mechanisms by systematically adjusting the tunnelling coupling in a wide range, including the limit of an isolated quantum dot. These experiments reveal fundamental limits and trade-offs of quantum dot spin dynamics: while reduced tunnelling can be used to achieve electron spin qubit lifetimes exceeding 1 s, the optical spin initialisation fidelity is reduced below 80%, limited by Auger recombination. Comprehensive understanding of electron-nuclear spin relaxation attained here provides a roadmap for design of the optimal operating conditions in quantum dot spin qubits.

Topological defects (TDs) manifest in many condensed matter systems. In liquid crystals (LCs), they occur as point or line singularities in the otherwise smooth director profile. Engineered and controllable TDs are of great interest for functional optoelectronic devices; however, the formation mechanism in patterned devices is not fully understood. In this work, electrically addressable TDs in doped mixtures of prototypical n‐alkyl‐cyanobiphenyl LCs 4‐cyano‐4′‐pentylbiphenyl (5CB) and 4‐cyano‐4′‐octylbiphenyl (8CB) are focused on. Doping concentrations of hexadecyltrimethylammonium bromide (CTAB) are varied and the effect of varying the host LC properties (through binary 5CB:8CB mixtures) on defect formation is studied. In the results, a strong correlation between LC “fluidity” and the ease of defect array formation is presented, with 0.5 wt% CTAB‐doped 5CB giving the best controllability/uniformity of TDs at low‐threshold voltages. Furthermore, it is demonstrated that the devices can be utilized as electrically switchable optical diffractive elements. In these findings, directions are mapped out that future studies can take in designing deterministic, electrically or magnetically tunable TD‐based photonic devices using LC systems. Electrically induced, reconfigurable topological defect arrays can be generated in an ionic‐doped liquid crystal medium. Time‐varying electric fields applied to micropatterned devices induce electro‐hydrodynamic instabilities that lead to ordered defect arrays with integer topological charge. The application of the devices as tunable, electrically addressable optical diffraction elements is demonstrated.

Visible light active g-C N /CeO /Fe O ternary composite nanosheets were fabricated by facile co-precipitation routes. The density functional theory (DFT) computations investigated changes in geometry and electronic character of g-C N with CeO and Fe O addition. Chemical and surface characterizations were explored with XRD, XPS, SEM, TEM, PL, DRS and Raman measurements. DRS and PL spectroscopy evidenced the energy band gap tailoring from 2.68 eV for bulk g-C N and 2.92 eV for CeO to 2.45 eV for the ternary nanocomposite. Efficient electron/hole pair separation, increase in red-ox species and high exploitation of solar spectrum due to band gap tailoring lead to higher degradation efficiency of g-C N /CeO /Fe O . Superior sun light photocatalytic breakdown of 2-Chlorophenol was observed with g-C N having CeO loading up to 5 wt%. In case of ternary nanocomposites deposition of 1 wt% Fe O over g-C N /CeO binary composite not only showed increment in visible light catalysis as predicted by the DFT studies, but also facilitated magnetic recovery. The g-C N /CeO /Fe O nanosheets showed complete mineralization of 25 mg.L 2-CP within 180 min exposure to visible portion of sun light and retained its high activity for 3 consecutive reuse cycles. The free radical scavenging showed superoxide ions and holes played a significant role compared to hydroxyl free radicals while chromatographic studies helped establish the 2-CP degradation mechanism. The kinetics investigations revealed 2.55 and 4.04 times increased rate of reactions compared to pristine Fe O and CeO , showing highest rate constant value of 18.2 × 10  min for the ternary nanocomposite. We present very persuasive results that can be beneficial for exploration of further potential of g-C N /CeO /Fe O in advance wastewater treatment systems.

Non-resonant cavity-quantum dot coupling is an interesting phenomenon with significant consequences for solid state single-photon sources. Here we present studies on the origin of the coupling mechanism by resonant excitation of single quantum dots in micro-pillar cavities. Furthermore, we demonstrate the non-resonant coupling as a powerful tool to 'monitor' the s-shell properties of a quantum dot by observing the behavior of a detuned coupled cavity mode.

Hyperbolic crystals like {\\alpha}-MoO\\(_3\\) can support large wavevectors and photon density as compared to the commonly used dielectric crystals, which makes them a highly desirable platform for compact photonic devices. The extreme anisotropy of the dielectric constant in these crystals is intricately linked with the anisotropic character of the phonons, which along with photon confinement leads to the rich physics of phonon polaritons. However, the chiral nature of phonons in these hyperbolic crystals have not been studied in detail. In this study, we report our observations of helicity selective Raman scattering from flakes of {\\alpha}-MoO\\(_3\\). Both helicity-preserving and helicity-reversing Raman scattering are observed. We observe that helical selectivity is largely governed by the underlying crystal symmetry. This study shed light on the chiral character of the high symmetry phonons in these hyperbolic crystals. It paves the way for exploiting proposed schemes of coupling chiral phonon modes into propagating surface plasmon polaritons and for compact photonic circuits based on helical polarized light.

Commercially impactful quantum algorithms such as quantum chemistry and Shor's algorithm require a number of qubits and gates far beyond the capacity of any existing quantum processor. Distributed architectures, which scale horizontally by networking modules, provide a route to commercial utility and will eventually surpass the capability of any single quantum computing module. Such processors consume remote entanglement distributed between modules to realize distributed quantum logic. Networked quantum computers will therefore require the capability to rapidly distribute high fidelity entanglement between modules. Here we present preliminary demonstrations of some key distributed quantum computing protocols on silicon T centres in isotopically-enriched silicon. We demonstrate the distribution of entanglement between modules and consume it to apply a teleported gate sequence, establishing a proof-of-concept for T centres as a distributed quantum computing and networking platform.

GaAs/AlGaAs quantum dots grown by in-situ droplet etching and nanohole infilling offer a combination of strong charge confinement, optical efficiency, and spatial symmetry required for polarization entanglement and spin-photon interface. Here we study spin properties of such dots. We find nearly vanishing electron \\(g\\)-factor (\\(g_e<0.05\\)), providing a route for electrically driven spin control schemes. Optical manipulation of the nuclear spin environment is demonstrated with nuclear spin polarization up to \\(60\\%\\) achieved. NMR spectroscopy reveals the structure of two types of quantum dots and yields the small magnitude of residual strain \\(\\epsilon_b<0.02\\%\\) which nevertheless leads to long nuclear spin lifetimes exceeding 1000 s. The stability of the nuclear spin environment is advantageous for applications in quantum information processing.

We present both experimental and theoretical investigations of a laser-driven quantum dot (QD) in the dressed-state regime of resonance fluorescence. We explore the role of phonon scattering and pure dephasing on the detuning-dependence of the Mollow triplet and show that the triplet sidebands may spectrally broaden or narrow with increasing detuning. Based on a polaron master equation approach which includes electron-phonon interaction nonperturbatively, we derive a fully analytical expression for the spectrum. With respect to detuning dependence, we identify a crossover between the regimes of spectral sideband narrowing or broadening. A comparison of the theoretical predictions to detailed experimental studies on the laser detuning-dependence of Mollow triplet resonance emission from single In(Ga)As QDs reveals excellent agreement.

Emission from a resonantly excited quantum emitter is a fascinating research topic within quantum optics and a useful source for different types of quantum light fields. The resonance spectrum consists of a single spectral line below saturation of a quantum emitter which develops into a triplet at powers above saturation of the emitter. The spectral properties of the triplet strongly depends on pump power and detuning of the excitation laser. The three closely spaced photon channels from the resonance fluorescence have different photon statistical signatures. We present a detailed photon-statistics analysis of the resonance fluorescence emission triplet from a solid state-based artificial atom, i.e. a semiconductor quantum dot. The photon correlation measurements demonstrate both 'single' and 'heralded' photon emission from the Mollow triplet sidebands. The ultra-bright and narrowband emission (5.9 MHz into the first lens) can be conveniently frequency-tuned by laser detuning over 15 times its linewidth ({\\Delta \\nu} \\approx 1.0 GHz). These unique properties make the Mollow triplet sideband emission a valuable light source for, e.g.quantum light spectroscopy and quantum information applications.