Terahertz phononic crystal in plasmonic nanocavity

Interaction between photons and phonons in cavity optomechanical systems provides a new toolbox for quantum information technologies.A GaAs/AlAs pillar multi-optical mode microcavity optomechanical structure can obtain phonons with ultra-high frequency(~THz).However,the optical field cannot be effectively restricted when the diameter of the GaAs/AlAs pillar microcavity decreases below the diffraction limit of light.Here,we design a system that combines Ag nanocav-ity with GaAs/AlAs phononic superlattices,where phonons with the frequency of 4.2 THz can be confined in a pillar with~4 nm diameter.The Q_(c)/V reaches 0.22 nm^(-3),which is~80 times that of the photonic crystal(PhC)nanobeam and~100 times that of the hybrid point-defect PhC bowtie plasmonic nanocavity,where Q_(c) is optical quality factor and V is mode volume.The optome-chanical single-photon coupling strength can reach 12 MHz,which is an order of magnitude larger than that of the PhC nanobeam.In addition,the mechanical zero-point fluctuation amplitude is 85 fm and the efficient mass is 0.27 zg,which is much smaller than the PhC nanobeam.The phononic superlattice-Ag nanocavity optomechanical devices hold great potential for applications in the field of integrated quantum optomechanics,quantum information,and terahertz-light transducer.

Room-temperature phonon-coupled single-photon emission in hexagonal boron nitride

Photon-lattice(phonon)coupling is fundamental to light-matter interaction,particularly when it reaches the quantum limit of the phonon-coupled single-photon emission,which holds great potential for quantum manipulation and quantum information transduction.Here,we report single defect state-phonon coupling in hexagonal boron nitride(h BN)at room temperature.An ultrabroad spectrum of single-photon emissions can be achieved by selecting the excitation energies.Using photoluminescence excitation spectroscopy,we observe single-phonon-assisted resonance-enhanced single-photon emission,along with multiple phonon replicas that herald the creation of phonon Fock state.We also develop a transition model to gain insight into the physical process behind the single defect state-phonon coupling.Our work sets the stage for manipulating electron-phonon coupling state with single quantum-level precision at room temperature.

Detecting nanoparticles by“listening”

In the macroscopic world,we can obtain some important information through the vibration of objects,that is,listening to the sound.Likewise,we can also get some information of the nanoparticles that we want to know by the means of“listening”in the microscopic world.In this review,we will introduce two sensing methods(cavity optomechanical sensing and surface-enhanced Raman scattering sensing)which can be used to detect the nanoparticles.The cavity optomechanical systems are mainly used to detect sub-gigahertz nanoparticle or cavity vibrations,while surface-enhanced Raman scattering is a well-known technique to detect molecular vibrations whose frequency generally exceeds terahertz.Therefore,the vibrational information of nanoparticles from low-frequency to high-frequency could be obtained by these two methods.The size of the viruses is at the nanoscale and we can regard it as a kind of nanoparticles.Rapid and ultrasensitive detection of the viruses is the key strategies to break the spread of the viruses in the community.Cavity optomechanical sensing enables rapid,ultrasensitive detection of nanoparticles through the interaction of light and mechanical oscillators and surface-enhanced Raman scattering is an attractive qualitatively analytical technique for chemical sensing and biomedical applications,which has been used to detect the SARS-CoV-2 infected.Hence,investigation in these two fields is of vital importance in preventing the spread of the virus from affecting human’s life and health.

Refrigeration technologies of cryogenic chips

Cryogenic electronics refers to the devices and circuits operated at cryogenic temperatures(below 123.15 K),which are made from a variety of materials such as insulators,conductors,semiconductors,superconductors and topological materials.The cryogenic electronics are endowed with some unique advantages that cannot be realized in room temperature,including high computing speed,high power performance and so on.Choosing the appropriate refrigeration tech-nology is critical for achieving the best performance of the cryogenic electronics.In this review,the cryogenic technology was divided into non-optical refrigeration and optical refrigeration,where non-optical refrigeration technologies are relatively conventional refrigeration technologies,while optical refrigeration is an emerging research field for the cooling of the chips.In the current work,the fundamental principles,applications and development prospects of the non-optical refrigeration was introduced,also the research history,fundamental principles,existing problems and application prospects of the optical refrigeration was thoroughly reviewed.