Genome-level diversification of eight ancient tea populations in the Guizhou and Yunnan regions identifies candidate genes for core agronomic traits

The ancient tea plant,as a precious natural resource and source of tea plant genetic diversity,is of great value for studying the evolutionary mechanism,diversification,and domestication of plants.The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood.Here,we report the genome resequencing of eight different groups consisting of 120 ancient tea plants:six groups from Guizhou Province and two groups from Yunnan Province.Based on the 8,082,370 identified high-quality SNPs,we constructed phylogenetic relationships,assessed population structure,and performed genome-wide association studies(GWAS).Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches,which is consistent with the results of principal component analysis(PCA).Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis.Moreover,it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding(nonsynonymous/synonymous=1.05).By integrating GWAS,selection signals,and gene function prediction,four candidate genes were significantly associated with three leaf traits,and two candidate genes were significantly associated with plant type.These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

Dynamics of two levitated nanospheres nonlinearly coupling with non-Markovian environment

The dynamics of two nanospheres nonlinearly coupling with non-Markovian reservoir is investigated. A master equation of the two nanospheres is derived by employing quantum state diffusion method. It is shown that the nonlinear coupling can improve the non-Markovianity. Due to the sharing of the common non-Markovian environment, the state transfer between the two nanospheres can be realized. The entanglement and the squeezing of the individual mode, as well as the jointed two-mode are analyzed. The present system can be realized by trapping two nanospheres in a wideband cavity, which might provide a method to study adjustable non-Markovian dynamics of mechanical motion.

Remote weak-signal measurement via bound states in optomechanical systems

A scheme for remote weak-signal sensors is proposed,in which a coupled-resonator optical waveguide(CROW),as a transmitter,couples to a hybrid optomechanical cavity and an observing cavity at its two ends.Non-Markovian theory is employed to study the weak-force sensor by treating the CROW as a non-Markovian reservoir of cavity fields.The dissipationless bound states in the non-Markovian regime are conducive to remotely transmitting a signal in the CROW.Our results show that a sensor with ultrahigh sensitivity can be achieved with the assistance of bound states under certain parameter regimes.

Suppressing laser phase noise in an optomechanical system

We propose a scheme to suppress the laser phase noise without increasing the optomechanical single-photon coupling strength.In the scheme,the parametric amplification terms,created by Kerr and Duffing nonlinearities,can restrain laser phase noise and strengthen the effective optomechanical coupling,respectively.Interestingly,decreasing laser phase noise leads to increasing thermal noise,which is inhibited by bringing in a broadband-squeezed vacuum environment.To reflect the superiority of the scheme,we simulate quantum memory and stationary optomechanical entanglement as examples,and the corresponding numerical results demonstrate that the laser phase noise is extremely suppressed.Our method can pave the way for studying other quantum phenomena.

Strong mechanical squeezing in an optomechanical system based on Lyapunov control

We propose a scheme to generate strong squeezing of a mechanical oscillator in an optomechanical system through Lyapunov control.Frequency modulation of the mechanical oscillator is designed via Lyapunov control.We show that the momentum variance of the mechanical oscillator decreases with time evolution in a weak coupling case.As a result,strong mechanical squeezing is realized quickly(beyond 3 d B).In addition,the proposal is immune to cavity decay.Moreover,we show that the obtained squeezing can be detected via an ancillary cavity mode with homodyne detection.