Probing PT-Symmetry Breaking of Non-Hermitian Topological Photonic States via Strong Photon-Magnon Coupling.

Light-matter interaction is crucial to both understanding fundamental phenomena and developing versatile applications. Strong coupling, robustness, and controllability are the three most important aspects in realizing light-matter interactions. Topological and non-Hermitian photonics have provided frameworks for robustness and control flexibility, respectively. How to engineer the properties of the edge state such as photonic density of state by using non-Hermiticity while ensuring topological protection has not been fully studied. Here we construct a parity-time-symmetric dimerized photonic lattice and probe the spontaneous PT-symmetry breaking of the edge states by utilizing the strong coupling between the photonic mode and a spin ensemble. Our Letter presents an accurate and almost noninvasive approach for investigating non-Hermitian topological states, while also offering methodologies for the implementation and manipulation of topological light-matter interactions.

Photonic Floquet Skin-Topological Effect.

Non-Hermitian skin effect and photonic topological edge states are of great interest in non-Hermitian physics and optics. However, the interplay between them is largely unexplored. Here, we propose and demonstrate experimentally the non-Hermitian skin effect constructed from the nonreciprocal flow of Floquet topological edge states, which can be dubbed "Floquet skin-topological effect." We first show the non-Hermitian skin effect can be induced by structured loss when the one-dimensional (1D) system is periodically driven. Next, based on a two-dimensional (2D) Floquet topological photonic lattice with structured loss, we investigate the interaction between the non-Hermiticity and the topological edge states. We observe that all the one-way edge states are imposed onto specific corners, featuring both the non-Hermitian skin effect and topological edge states. Furthermore, a topological switch for the skin-topological effect is presented by utilizing the phase-transition mechanism. Our experiment paves the way for realizing non-Hermitian topological effects in nonlinear and quantum regimes.

The effects of video double-lumen tubes on intubation complications in patients undergoing thoracic surgery: A randomised controlled study.

BACKGROUND: Tracheal injuries, vocal cord injuries, sore throat and hoarseness are common complications of double-lumen tube (DLT) intubation. OBJECTIVE: This study aimed to evaluate the effects of 'video double-lumen tubes' (VDLTs) on intubation complications in patients undergoing thoracic surgery. DESIGN: A randomised controlled study. SETTINGT: Xuzhou Cancer Hospital, Xuzhou, China, from January 2023 to June 2023. PATIENTS: One hundred eighty-two patients undergoing elective thoracic surgery with one-lung ventilation were randomised into two groups: 90 in the DLT group and 92 in the VDLT group. INTERVENTION: VDLT was selected for intubation in the VDLT group, and DLT was selected for intubation in the DLT group. A fibreoptic bronchoscope (FOB) was used to record tracheal and vocal cord injuries. MAIN OUTCOME MEASURES: The primary outcomes were the incidence of moderate-to-severe tracheal injury and the incidence of vocal cord injury. The secondary outcomes included the incidence and severity of postoperative 24 and 48 h sore throat and hoarseness. RESULTS: The incidence of moderate-to-severe tracheal injury was 32/90 (35.6%) in the DLT group, and 45/92 (48.9%) in the VDLT group ( P  = 0.077; relative risk 1.38, 95% CI, 0.97 to 1.95). The incidence of vocal cord injury was 31/90 (34.4%) and 34/92 (37%) in the DLT and VDLT groups, respectively ( P  = 0.449). The incidence of postoperative 24 h sore throat and hoarseness was significantly higher in the VDLT group than in the DLT group (for sore throat: P  = 0.032, relative risk 1.63, 95% CI, 1.03 to 2.57; for hoarseness: P  = 0.018, relative risk 1.48, 95% CI, 1.06 to 2.06). CONCLUSION: There was no statistically significant difference in the incidence of moderate-to-severe tracheal injury and vocal cord injury between DLTs and VDLTs. While improving the first-attempt success rate, intubation with VDLT increased the incidence of postoperative 24 h sore throat and hoarseness. TRIAL REGISTRATION: Chinese Clinical Trial Registry identifier: ChiCTR2300067348.

Spatial multiplexing for robust optical vortex transmission with optical nonlinearity.

Optical vortex beams, with phase singularity characterized by a topological charge (TC), introduces a new dimension for optical communication, quantum information, and optical light manipulation. However, the evaluation of TCs after beam propagation remains a substantial challenge, impeding practical applications. Here, we introduce vortices in lateral arrays (VOILA), a novel spatial multiplexing approach that enables simultaneous transmission of a lateral array of multiple vortices. Leveraging advanced learning techniques, VOILA effectively decodes TCs, even in the presence of strong optical nonlinearities simulated experimentally. Notably, our approach achieves substantial improvements in single-shot bandwidth, surpassing single-vortex scheme by several orders of magnitude. Furthermore, our system exhibits precise fractional TC recognition in both linear and nonlinear regimes, providing possibilities for high-bandwidth communication. The capabilities of VOILA promise transformative contributions to optical information processing and structured light research, with significant potential for advancements in diverse fields.

Quantum Induced Coherence Light Detection and Ranging.

Quantum illumination has been proposed and demonstrated to improve the signal-to-noise ratio (SNR) in light detection and ranging (LiDAR). When relying on coincidence detection alone, such a quantum LiDAR is limited by the timing jitter of the detector and suffers from jamming noise. Inspired by the Zou-Wang-Mandel experiment, we design, construct, and validate a quantum induced coherence (QuIC) LiDAR which is inherently immune to ambient and jamming noises. In traditional LiDAR the direct detection of the reflected probe photons suffers from deteriorating SNR for increasing background noise. In QuIC LiDAR we circumvent this obstacle by only detecting the entangled reference photons, whose single-photon interference fringes are used to obtain the distance of the object, while the reflected probe photons are used to erase path information of the reference photons. In consequence, the noise accompanying the reflected probe light has no effect on the detected signal. We demonstrate such noise resilience with both LED and laser light to mimic the background and jamming noise. The proposed method paves a new way of battling noise in precise quantum electromagnetic sensing and ranging.

Quantum Control of a Single Magnon in a Macroscopic Spin System.

Nonclassical quantum states are the pivotal features of a quantum system that differs from its classical counterpart. However, the generation and coherent control of quantum states in a macroscopic spin system remain an outstanding challenge. Here we experimentally demonstrate the quantum control of a single magnon in a macroscopic spin system (i.e., 1 mm-diameter yttrium-iron-garnet sphere) coupled to a superconducting qubit via a microwave cavity. By tuning the qubit frequency in situ via the Autler-Townes effect, we manipulate this single magnon to generate its nonclassical quantum states, including the single-magnon state and the superposition of single-magnon state and vacuum (zero magnon) state. Moreover, we confirm the deterministic generation of these nonclassical states by Wigner tomography. Our experiment offers the first reported deterministic generation of the nonclassical quantum states in a macroscopic spin system and paves a way to explore its promising applications in quantum engineering.

Gold nanoparticles retrogradely penetrate through testicular barriers via Sertoli-cells mediated endocytosis/exocytosis and induce immune response in mouse.

Despite the rapidly growing interest in nanoparticle-mediated controllable male contraception and recovery of male fertility, novel applications of nanoparticles in these processes are limited by a knowledge gap regarding their transport and distribution in the testes. Here, we investigated the fate of gold nanoparticles in the mouse testes using two injection methods, namely, interstitial testicular injection (IT-AuNPs, AuNPs exposure in the interstitial compartment of the testes) and rete testis injection (RT-AuNPs, AuNPs exposure in the adluminal compartment of the seminiferous tubules). In this study, we used 100 nm spherical AuNPs and microinjected with 5 µL AuNPs (30 mg/mL) for the experiments. For IT-AuNP injection, we found that AuNPs could not penetrate through the Sertoli cell-mediated blood-testis barrier (BTB) of the seminiferous tubules, and no male reproductive toxicity was observed. For RT-AuNP injection, AuNPs could be retrogradely transported from the adluminal compartment to the interstitial compartment of the testes via Sertoli cell-mediated endocytosis/exocytosis, resulting in damage and the release of inflammatory cytokines in the mouse testis. Our results highlight a retrograde nanoparticle transport function of Sertoli cells, thereby providing a mechanistic overview of the development and use of nanobiotechnology in male reproduction. SYNOPSIS: This study provides new insights into male reproductive immunotoxicity for AuNPs exposure and elucidates a mechanism via Sertoli cell-mediated endocytosis/exocytosis.

Floquet Superradiance Lattices in Thermal Atoms.

Floquet modulation has been widely used in optical lattices for coherent control of quantum gases, in particular for synthesizing artificial gauge fields and simulating topological matters. However, such modulation induces heating which can overwhelm the signal of quantum dynamics in ultracold atoms. Here we report that the thermal motion, instead of being a noise source, provides a new control knob in Floquet-modulated superradiance lattices, which are momentum-space tight-binding lattices of collectively excited states of atoms. The Doppler shifts combined with Floquet modulation provide effective forces along arbitrary directions in a lattice in frequency and momentum dimensions. Dynamic localization, dynamic delocalization, and chiral edge currents can be simultaneously observed from a single transport spectrum of superradiance lattices in thermal atoms. Our Letter paves a way for simulating Floquet topological matters in room-temperature atoms and facilitates their applications in photonic devices.

Synthesizing Five-Body Interaction in a Superconducting Quantum Circuit.

Synthesizing many-body interaction Hamiltonians is a central task in quantum simulation. However, it is challenging to synthesize Hamiltonians that have more than two spins in a single term. Here we synthesize m-body spin-exchange Hamiltonians with m up to 5 in a superconducting quantum circuit by simultaneously exciting multiple independent qubits with time-energy correlated photons generated from a qudit. The dynamic evolution of the m-body interaction is governed by the Rabi oscillation between two m-spin states, in which the states of each spin are different. We demonstrate the scalability of our approach by comparing the influence of noises on the three-, four- and five-body interaction and building a many-body Mach-Zehnder interferometer which potentially has a Heisenberg-limit sensitivity. This study paves a way for quantum simulation involving many-body interaction Hamiltonians such as lattice gauge theories in quantum circuits.

Long-Time Memory and Ternary Logic Gate Using a Multistable Cavity Magnonic System.

Multistability is an extraordinary nonlinear property of dynamical systems and can be explored to implement memory and switches. Here we experimentally realize the tristability in a three-mode cavity magnonic system with Kerr nonlinearity. The three stable states in the tristable region correspond to the stable solutions of the frequency shift of the cavity magnon polariton under specific driving conditions. We find that the system staying in which stable state depends on the history experienced by the system, and this state can be harnessed to store the history information. In our experiment, the memory time can reach as long as 5.11 s. Moreover, we demonstrate the ternary logic gate with good on-off characteristics using this multistable hybrid system. Our new findings pave a way towards cavity magnonics-based information storage and processing.

Flat-Band Localization in Creutz Superradiance Lattices.

Flat bands play an important role in diffraction-free photonics and attract fundamental interest in many-body physics. Here we report the engineering of flat-band localization of collective excited states of atoms in Creutz superradiance lattices with tunable synthetic gauge fields. Magnitudes and phases of the lattice hopping coefficients can be independently tuned to control the state components of the flat band and the Aharonov-Bohm phases. We can selectively excite the flat band and control the flat-band localization with the synthetic gauge field. Our study provides a room-temperature platform for flat bands of atoms and holds promising applications in exploring correlated topological materials.

Observation of the interplay between seeded and self-seeded nondegenerate four-wave mixing in cesium vapor.

Nondegenerate four-wave mixing (NFWM) is a practical and effective technique for generating or amplifying light fields at different wavelengths, and could be used to create color correlation and entanglement. Here we experimentally investigate the NFWM process in diamond atomic system via two-photon excitation with two pumps at 852 nm and 921 nm, demonstrating that a seeded NFWM with a third laser at 895 nm and two self-seeded NFWMs due to amplified spontaneous emission (ASE) occur simultaneously. We compare the two kinds of processes and show that the single- and two-photon detunings hold the key role in distinguishing them. As a result, the enhancement of seeded NFWM is obtained by selecting large one- and two-photon detunings, in which case the ASE induced self-seeded NFWM can be largely suppressed. In contrast, the ASE and its induced NFWM are effectively achieved with one- and two-photon resonant excitations allowing for population inversion for efficient ASE.

Simultaneous Excitation of Two Noninteracting Atoms with Time-Frequency Correlated Photon Pairs in a Superconducting Circuit.

We report the first observation of simultaneous excitation of two noninteracting atoms by a pair of time-frequency correlated photons in a superconducting circuit. The strong coupling regime of this process enables the synthesis of a three-body interaction Hamiltonian, which allows the generation of the tripartite Greenberger-Horne-Zeilinger state in a single step with a fidelity as high as 0.95. We further demonstrate the inhibition of the simultaneous two-atom excitation by continuously measuring whether the first photon is emitted. This work provides a new route in synthesizing many-body interaction Hamiltonian and coherent control of entanglement.

Vortex strength and beam propagation factor of fractional vortex beams.

Fractional vortex beams (FVBs) with non-integer topological charges attract much attention due to unique features of propagations, but different viewpoints still exist on the change of their total vortex strength. Here we have experimentally demonstrated the distribution and number of vortices contained in FVBs at the Fraunhofer diffraction region. We have verified that the jumps of total vortex strength for FVBs happen only when non-integer topological charge is before and after (but very close to) any even integer number that originates from two different mechanisms for generation and movement of vortices on focal plane. Meanwhile, we have also measured the beam propagation factor (BPF) of such FVBs and have found that their BPF values almost increase linearly in the x component (along the initial edge dislocation) and oscillate increasingly in the y component (vertical to the initial edge dislocation). Our experimental results are in good agreement with numerical results.

Experimental Observation of Momentum-Space Chiral Edge Currents in Room-Temperature Atoms.

Chiral edge currents play an important role in characterizing topological matter. In atoms, they have been observed at such a low temperature that the atomic motion can be measured. Here we report the first experimental observation of chiral edge currents in atoms at room temperature. Staggered magnetic fluxes are induced by the spatial phase difference between two standing-wave light fields, which couple atoms to form a momentum-space zigzag superradiance lattice. The chiral edge currents are measured by comparing the directional superradiant emissions of two timed Dicke states in the lattice. Our results pave the way for simulating topological physics in hot atoms.

Long-range in situ picometer measurement of the period of an interference field.

A scanning reference grating (SRG) method is proposed for high-precision in situ measuring and controlling the period of a long-range interference field. The reference grating is produced with the in situ interference field; then it is used to obtain phase shift signal when scanning in the interference field. With the phase shift signal collected by the SRG system, before the exposure process of the holographic grating fabrication, the period and the period uniformity of the holographic grating can be evaluated directly from the interference field; then optical adjustment can be applied until the grating period is tuned to any certain desired value. Experiments of measurement and adjustment are conducted, and an interference field with period value of 833.335 nm±10 pm in 60 mm range is reached. The proposed method gives an efficient way to fabricate large gratings of an accurate period; furthermore, it provides a reliable tool that may lead us to picometer-level optical metrology and fabrication for the most advanced lithographic equipment and in other scientific fields.

Improvement of reliability in multi-interferometer-based counterfactual deterministic communication with dissipation compensation.

The direct counterfactual quantum communication (DCQC) is a surprising phenomenon that quantum information can be transmitted without using any carriers of physical particles. The nested interferometers are promising devices for realizing DCQC as long as the number of interferometers goes to be infinity. Considering the inevitable loss or dissipation in practical experimental interferometers, we analyze the dependence of reliability on the number of interferometers, and show that the reliability of direct communication is being rapidly degraded with the large number of interferometers. Furthermore, we simulate and test this counterfactual deterministic communication protocol with a finite number of interferometers, and demonstrate the improvement of the reliability using dissipation compensation in interferometers.

Magnon-Photon-Phonon Entanglement in Cavity Magnomechanics.

We show how to generate tripartite entanglement in a cavity magnomechanical system which consists of magnons, cavity microwave photons, and phonons. The magnons are embodied by a collective motion of a large number of spins in a macroscopic ferrimagnet, and are driven directly by an electromagnetic field. The cavity photons and magnons are coupled via magnetic dipole interaction, and the magnons and phonons are coupled via magnetostrictive (radiation pressurelike) interaction. We show optimal parameter regimes for achieving the tripartite entanglement where magnons, cavity photons, and phonons are entangled with each other, and we further prove that the steady state of the system is a genuinely tripartite entangled state. The entanglement is robust against temperature. Our results indicate that cavity magnomechanical systems could provide a promising platform for the study of macroscopic quantum phenomena.

Experimental Observation of One-Dimensional Superradiance Lattices in Ultracold Atoms.

We measure the superradiant emission in a one-dimensional (1D) superradiance lattice (SL) in ultracold atoms. Resonantly excited to a superradiant state, the atoms are further coupled to other collectively excited states, which form a 1D SL. The directional emission of one of the superradiant excited states in the 1D SL is measured. The emission spectra depend on the band structure, which can be controlled by the frequency and intensity of the coupling laser fields. This work provides a platform for investigating the collective Lamb shift of resonantly excited superradiant states in Bose-Einstein condensates and paves the way for realizing higher dimensional superradiance lattices.

Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.

We report the experimental manipulation of the group velocities of reflected and transmitted light pulses in a degenerate two-level atomic system driven by a standing wave, which is created by two counter-propagating light beams of equal frequencies but variable amplitudes. It is shown that the light pulse is reflected with superluminal group velocity while the transmitted pulse propagates from subluminal to superluminal velocities via changing the power of the backward coupling field. We find that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms. The theoretical discussion shows that the anomalous dispersion associated with a resonant absorption dip within the gain peak due to four-wave mixing leads to the superluminal reflection, while the varying dispersion from normal to anomalous at transparency, transparency within absorption, and electromagnetically induced absorption windows leads to the subluminal to superluminal transmission.