Stochastic resonance(SR) has been proved to be an effective approach to extract weak signals overwhelmed in noise.However, the detection effect of current SR models is still unsatisfactory. Here, a coupled tri-stable stochastic resonance(CTSSR) model is proposed to further increase the output signal-to-noise ratio(SNR) and improve the detection effect of SR. The effects of parameters a, b, c, and r in the proposed resonance system on the SNR are studied, by which we determine a set of parameters that is relatively optimal to implement a comparison with other classical SR models.Numerical experiment results indicate that this proposed model performs better in weak signal detection applications than the classical ones with merits of higher output SNR and better anti-noise capability.
Recently, a genuine six-qubit entangled state |six> has been proposed [Chen P X, et al. Phys Rev A, 2006, 74: 032324]. This state does not belong to the well-known three types of multipartite entangled states, i.e., Greenberger-Horne-Zeilinger (GHZ) state, W state, and linear cluster state. This state has many potential applications in quantum information processing. We propose a scheme for generating such a genuine six-qubit entangled state for trapped ions in thermal motion. The scheme is insensitive to both the initial motional state and heating.
