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Non-Hermitian systems associated with exceptional points (EPs) are expected to demonstrate a giant response enhancement for various sensors. The widely investigated enhancement mechanism based on diverging from an EP should destroy the EP and further limits its applications for multiple sensing scenarios in a time sequence. To break the above limit, here we proposed a new enhanced sensing mechanism based on shifting an EP. Different from the mechanism of diverging from an EP, our scheme is an EP non-demolition and the giant enhancement of response is acquired by a slight shift of the EP along the parameter axis induced by perturbation. The new sensing mechanism can promise the most ffective response enhancement for all sensors in the case of multiple sensing in a time sequence. To verify our sensing mechanism, we construct a mass sensor and a gyroscope with concrete physical implementations. Our work will deepen the understanding of EP-based sensing and inspire designing various high sensitivity sensors in different physical systems., Comment: 7 pages, 3 figures

Dynamic encircling a second-order exception point (EP) exhibit chiral state transfer, while there is few research on dynamic encircling multiple and higher-order EPs. Here, we study proximity-encirclement of the EPs in a multimode optomechanical system to understand the closed path evolution of high-order non-Hermitian systems. The optomechanical system has three types of situations about EPs: the system has no EP, a pair of second-order EPs, and a third-order EP. The dynamical behavior of the system's dependence on the initial state, orientation, and velocity of the loop, the variance in the starting point of the loop, as well as the number and order of EPs encircled by the loop have been investigated in the process of state transfer. The results show that chiral or non-reciprocal state transfer can be realized when the loop encircling a second-order EP with different radius. Only chiral state transfer occurs when encircling two second-order EPs. Moreover, chiral and non-reciprocal state transfer can happen in a single loop encircling a third-order EP. The phenomena about encircling the EPs in a multimode optomechanical system provides another means for manipulating state transfer in higher-order non-Hermitian systems., Comment: 12 pages,11 figures. arXiv admin note: text overlap with arXiv:2208.01228

The ground state cooling of Brillouin scattering optomechanical system is limited by defects in practical sample. In this paper, we propose a new compensatory cooling mechanism for Brillouin scattering optomechanical system with exceptional points (EPs). By using the EPs both in optical and mechanical modes, the limited cooling process is compensated effectively. The dual-EPs system, which is discovered in this work for the first time, can be induced by two defects with specific relative angles and has function of not only actively manipulating the coupling strength of optical modes but also the Brillouin phonon modes. Our results provide new tools to manipulate the optomechanical interaction in multi-mode systems and open the possibility of quantum state transfer and quantum interface protocols based on phonon cooling in quantum applications., Comment: 6 pages, 5 figures

Dynamical encircling exceptional point(EP) shows a number of intriguing physical phenomena and its potential applications. To enrich the manipulations of optical systems in experiment, here, we study the dynamical encircling EP, i.e. state transfer process, in largely detuned multimode optomechanical system. The process of state transfer has been investigated with different factors about the location of start point, the orientation and the initial state of the trajectories around the EP in parameter space. Results show that the nonreciprocal and the chiral topological energy transfer between two optical modes are performed successfully by tuning the effective optomechanical coupling in the multimode system with large detuning. Moreover, the factor of evolution speed about system parameters is also discussed. Our work demonstrates the fundamental physics around EP in large detuning domain of multimode optomechanical system and provides an alternative for manipulating of optical modes in non-hermitian system., Comment: 9 pages,7 figures

Polarization beam splitter (PBS) is a crucial photonic element to separately extract transverse-electric (TE) and transverse-magnetic (TM) polarizations from the propagating light fields. Here, we propose a concise, continuously tunable and all-optical partial PBS in the vector optomechanical system which contains two orthogonal polarized cavity modes with degenerate frequency. The results show that one can manipulate the polarization states of different output fields by tuning the polarization angle of the pumping field and the system function as partial PBS when the pump laser polarizes vertically or horizontally. As a significant application of the tunable PBS, we propose a scheme of implementing quantum walks in resonator arrays without the aid of other auxiliary systems. Furthermore, we investigate the optomechanically induced Faraday effect in the vector optomechanical system which enables arbitrary tailoring of the input lights and the behaviors of polarization angles of the output fields in the under couple, critical couple, and over couple regimes. Our findings prove the optomechanical system is a potential platform to manipulate the polarization states in multimode resonators and boost the process of applications related to polarization modulation., Comment: 9 pages, 6 figures