Periodic Reporting for period 4 - TOPP (Topological phononics through nano-optomechanical interactions)
Okres sprawozdawczy: 2022-07-01 do 2023-06-30
The project aimed at uncovering topological behavior in nanophotonic systems, in particular by breaking time-reversal symmetry through nano-optomechanical interactions. Such behavior is normally alien to both photons and phonons as they do not interact with magnetic fields, in contrast to electrons. It can lead to highly sought-after functionality such as one-way transport and states that are protected against scattering from disorder. As such, it is appealing to introduce these principles in nanophotonic and nanomechanical systems, which are rich in applications related to sensing and information processing.
In on-chip silicon nanophotonic systems, we observed various topological states of phonons and photons, bearing analogy to the quantum Hall effect, the quantum spin Hall effect, and the quantum valley Hall effect known in electronic materials. We demonstrated the ability of such states to control nonreciprocal transport of signals as well as thermal flows, and propagation robust against scattering from defects. Moreover, by combining broken time-reversal symmetry with non-Hermitian dynamics, we discovered new phases of matter and physical mechanisms, including a geometric phase that controls non-Hermitian dynamics in parametrically driven systems, and a bosonic Kitaev-Majorana chain that establishes a non-Hermitian topological phase with intriguing applications as a sensor and amplifier. Finally, we uncovered rich dynamical behavior in nonlinear nano-optomechanical networks controlled with laser fields.
This project demonstrated a suite of new physical phenomena in topological bosonic systems. It showcased the power of on-chip silicon nanophotonic and nanomechanical systems to study such phenomena, with potential applications in various domains, and possible analogues in many other wave systems and metamaterials.
In on-chip silicon nanophotonic systems, we observed various topological states of phonons and photons, bearing analogy to the quantum Hall effect, the quantum spin Hall effect, and the quantum valley Hall effect known in electronic materials. We demonstrated the ability of such states to control nonreciprocal transport of signals as well as thermal flows, and propagation robust against scattering from defects. Moreover, by combining broken time-reversal symmetry with non-Hermitian dynamics, we discovered new phases of matter and physical mechanisms, including a geometric phase that controls non-Hermitian dynamics in parametrically driven systems, and a bosonic Kitaev-Majorana chain that establishes a non-Hermitian topological phase with intriguing applications as a sensor and amplifier. Finally, we uncovered rich dynamical behavior in nonlinear nano-optomechanical networks controlled with laser fields.
This project demonstrated a suite of new physical phenomena in topological bosonic systems. It showcased the power of on-chip silicon nanophotonic and nanomechanical systems to study such phenomena, with potential applications in various domains, and possible analogues in many other wave systems and metamaterials.
Enabled by radiation pressure control techniques and nanoscale system design, we aimed to induce topological behavior for light and sound at the nanoscale. We developed novel methods for the control and readout of bosonic topological states using on-chip silicon photonic crystal systems. We demonstrated effective magnetic fields for photons and phonons through the breaking of spatiotemporal symmetries. This led to the demonstration of nonreciprocal transport and spectral control mimicking the celebrated quantum Hall effect, including chiral phononic edge states, nonreciprocal control of thermal flows, an optomechanical Farady effect, and photonic flat-band Landau levels. We developed new methods based on far- and near-field imaging as well as synthetic dimensions to image the propagation of topological states in waveguides and cavities, and quantify their robustness against engineered defects. Controlling non-Hermitian dynamics through parametric optomechanical squeezing interactions, we discovered various interesting non-Hermitian bosonic phenomena that do not have a counterpart in electronic topological phases: (1) a novel geometric phase that controls non-Hermitian dynamics, (2) the phenomenon of quadrature nonreciprocity; unidirectional transport without breaking time-reversal symmetry, and (3) a bosonic analog of the Kitaev-Majorana chain; a new non-Hermitian topological phase with highly interesting application in sensing and directional amplification of signals. Moreover, we quantified nonlinear dynamics in optomechanical networks, demonstrating the enhancement of nonlinear effects in suitably engineered multimode resonators, stable phonon lasing, and nonlinear optical control over the phononic states of optomechanical meta-matter. The experimental results were complemented with the development of theories describing both the observed physical phenomena as well as the measurement and control techniques. The results were disseminated in over 15 peer-reviewed publications (with multiple others in review or preparation), and in more than 50 talks at international conferences, workshops, and institute seminars.
The aforementioned results go beyond the state of the art, in the sense that they show in theory and experiment that nonreciprocal and topological behavior can be induced in nanoscale optomechanical systems. They used new forms of spatial and time-reversal symmetry breaking to achieve such effects. As we scaled system size and merged the concepts of time-reversal symmetry breaking, non-Hermiticity, and nonlinearity along the course of the project, we uncovered rich emerging behavior in these systems, and various new physical phenomena with potential for applications and the study of new phases of matter in a wide range of possible metamaterials.