Qing Wang

Bio: Qing Wang is an academic researcher from Nanjing University. The author has contributed to research in topics: Acoustic wave & Dirac (software). The author has an hindex of 3, co-authored 6 publications receiving 132 citations.

Surface phononic graphene.

Abstract: Strategic manipulation of wave and particle transport in various media is the key driving force for modern information processing and communication. In a strongly scattering medium, waves and particles exhibit versatile transport characteristics such as localization, tunnelling with exponential decay, ballistic, and diffusion behaviours due to dynamical multiple scattering from strong scatters or impurities. Recent investigations of graphene have offered a unique approach, from a quantum point of view, to design the dispersion of electrons on demand, enabling relativistic massless Dirac quasiparticles, and thus inducing low-loss transport either ballistically or diffusively. Here, we report an experimental demonstration of an artificial phononic graphene tailored for surface phonons on a LiNbO3 integrated platform. The system exhibits Dirac quasiparticle-like transport, that is, pseudo-diffusion at the Dirac point, which gives rise to a thickness-independent temporal beating for transmitted pulses, an analogue of Zitterbewegung effects. The demonstrated fully integrated artificial phononic graphene platform here constitutes a step towards on-chip quantum simulators of graphene and unique monolithic electro-acoustic integrated circuits.

Acoustic asymmetric transmission based on time-dependent dynamical scattering.

Abstract: An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies.

Acoustic phase-reconstruction near the Dirac point of a triangular phononic crystal

Abstract: In this work, acoustic phase-reconstruction is studied and experimentally demonstrated in a triangular lattice two-dimensional phononic crystal (PnC) composed of steel rods in air. Owning to the fact that two bands of this triangular lattice PnC touch at the K/K′ point and thus give rise to a conical Dirac cone, acoustic waves transmitting through this PnC can exhibit a pseudo-diffusion transportation feature, producing a reconstructed planar wavefront in the far field away from the interface of the PnC. Such phase reconstruction effect can be utilized in many applications, and here we demonstrate experimentally two important applications: an acoustic collimator and an acoustic cloak operating at a Dirac frequency of 41.3 kHz.

Sound diode based on time-dependent modulation

Abstract: The invention provides a sound diode based on time-dependent modulation. The sound diode is composed of an oval pillar in a sound wave guide tube and a filter located at the tail end of the sound wave guide tube. The oval pillar is located in front of the filter and the sound wave guide tube is made of rigid materials. The oval pillar is driven by a motor to rotate and the filter is composed of Helmholtz resonant cavities which are located on the upper side and the lower side of the sound wave guide tube. In terms of the sound diode based on time-dependent modulation, in the working wave band, after sound waves which enter in the forward direction pass through the oval pillar which rotates at the speed of 65.5r/s, part of the frequency jumps to 131Hz and the sound waves can pass through the filter. Sound waves which enter in the backward direction pass through the filter at first and are directly filtered and the sound waves can not pass through the diode. According to the sound diode based on time-dependent modulation, sound rectification is achieved through time-dependent modulation and the working frequency of single-direction transmission is changed by changing the structural parameters and the center frequency of the filter. The bandwidth of the diode can be changed by changing the rotation speed and the bandwidth of the filter. The sound diode is not sensitive to angle, high in adaptability, simple in structure, easy to obtain and low in cost.

Bionics directional microphone based on meniane type metamaterials

Abstract: The invention provides a bionics directional microphone based on meniane type metamaterials. The bionics directional microphone comprises a meniane type metamaterial amplifier and a microphone body located at the rear end of the amplifier. The meniane type metamaterial amplifier is composed of a meniane structure at the front end and a resonant cavity at the rear end. The meniane structure is a closed structure formed by distributing a plurality of finger-cross structures in a staggered mode. A sound wave entrance port and a communication port connected with the resonant cavity at the rear end are formed in the meniane structure. The meniane structure and the resonant cavity are made of rigid materials. The microphone body stretches into a reserved duct in the rear end of the resonant cavity. According to the bionics directional microphone, on the basis of the acoustics metamaterials and the bionics principle, the acoustic directional effect is achieved, the frequency of acoustic directional signals of a target can be changed by changing structural parameters and the center frequency of the amplifier, and the novel acoustic directional microphone is high in adaptability, good in performance, simple in structure, easy to obtain and low in cost.

Acoustic metamaterials: From local resonances to broad horizons.

Abstract: Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature.

Topological phases in acoustic and mechanical systems

Abstract: The study of classical wave physics has been reinvigorated by incorporating the concept of the geometric phase, which has its roots in optics, and topological notions that were previously explored in condensed matter physics. Recently, sound waves and a variety of mechanical systems have emerged as excellent platforms that exemplify the universality and diversity of topological phases. In this Review, we introduce the essential physical concepts that underpin various classes of topological phenomena realized in acoustic and mechanical systems: Dirac points, the quantum Hall, quantum spin Hall and valley Hall effects, Floquet topological phases, 3D gapless states and Weyl crystals. This Review describes topological phenomena that can be realized in acoustic and mechanical systems. Methods of symmetry breaking are described, along with the consequences and rich phenomena that emerge.

Breaking the barriers: advances in acoustic functional materials

Abstract: Acoustics is a classical field of study that has witnessed tremendous developments over the past 25 years. Driven by the novel acoustic effects underpinned by phononic crystals with periodic modulation of elastic building blocks in wavelength scale and acoustic metamaterials with localized resonant units in subwavelength scale, researchers in diverse disciplines of physics, mathematics, and engineering have pushed the boundary of possibilities beyond those long held as unbreakable limits. More recently, structure designs guided by the physics of graphene and topological electronic states of matter have further broadened the whole field of acoustic metamaterials by phenomena that reproduce the quantum effects classically. Use of active energy-gain components, directed by the parity-time reversal symmetry principle, has led to some previously unexpected wave characteristics. It is the intention of this review to trace historically these exciting developments, substantiated by brief accounts of the salient milestones. The latter can include, but are not limited to, zero/negative refraction, subwavelength imaging, sound cloaking, total sound absorption, metasurface and phase engineering, Dirac physics and topology-inspired acoustic engineering, non-Hermitian parity-time synthetic active metamaterials, and one-way propagation of sound waves. These developments may underpin the next generation of acoustic materials and devices, and offer new methods for sound manipulation, leading to exciting applications in noise reduction, imaging, sensing and navigation, as well as communications.

Topological phononic insulator with robust pseudospin-dependent transport

Abstract: Topological phononic states, which facilitate unique acoustic transport around defects and disorders, have significantly revolutionized our scientific cognition of acoustic systems. Here, by introducing a zone folding mechanism, we realize the topological phase transition in a double Dirac cone of the rotatable triangular phononic crystal with ${C}_{3v}$ symmetry. We then investigate the distinct topological edge states on two types of interfaces of our phononic insulators. The first one is a zigzag interface which simultaneously possesses a symmetric mode and an antisymmetric mode. Hybridization of the two modes leads to a robust pseudospin-dependent one-way propagation. The second one is a linear interface with a symmetric mode or an antisymmetric mode. The type of mode is dependent on the topological phase transition of the phononic insulators. Based on the rotatability of triangular phononic crystals, we consider several complicated contours defined by the topological zigzag interfaces. Along these contours, the acoustic waves can unimpededly transmit without backscattering. Our research develops a route for the exploration of the topological phenomena in experiments and provides an excellent framework for freely steering the acoustic backscattering-immune propagation within topological phononic structures.