Fu-Quan Dou

High-fidelity superadiabatic population transfer of a two-level system with a linearly chirped Gaussian pulse

We investigate high-fidelity superadiabatic quantum driving in a chirped Gaussian two-level model with a Gaussian temporal envelope and a linear detuning. We show that the nonadiabatic losses can be canceled to any desired order by constructing and adjusting an auxiliary Hamiltonian (counter-diabatic field) and a symmetry in the fidelity arises on the counter-diabatic field ratio. A high-fidelity, robust, and accelerated (in a shorter time) transitionless superadiabatic population transfer is achieved that ensures a perfect following of the instantaneous adiabatic ground state even in the nonadiabatic regime. The features make the superadiabatic protocol a potentially important tool for quantum information.

Anti-synchronization of a new hyperchaotic system

The anti-synchronization problem of a new hyperchaotic system is investigated. Based on the active control theory, anti-synchronization not only between two identical hyperchaotic systems but particularly also between two different hyperchaotic systems is realized. Moreover, numerical simulations are applied to verify the effectiveness and feasibility of the proposed control technique.

Ramsey interferometry of a bosonic Josephson junction in an optical cavity

We investigate the nonlinear Ramsey interferometry of a bosonic Josephson junction coupled to an optical cavity by applying two identical pumping field pulses separated by a holding field in the time domain. When the holding field is absent, we show that the atomic Ramsey fringes are sensitive to both the cavity-pump detuning and the initial state, and their periods can encode the information on both the atom-field coupling and the atom-atom interaction. For a weak holding field, we find that the fringes characterized by the oscillation of the intra-cavity photon number can completely reflect the frequency information of the atomic interference due to the weak atom-cavity coupling. This finding allows a nondestructive observation of the atomic Ramsey fringes via the cavity transmission spectra.

Matter-wave interactions in two-component Bose-Einstein condensates

We investigate two vector-soliton–like matter waves collisions in two-component Bose-Einstein condensates with attractive interactions and Gaussian barrier. We present a detailed numerical analysis of the roles of atomic interactions, barrier, relative velocity, and relative phase in collisional dynamics. We show that the interspecies interactions are crucial to make the wave packet propagate as a “breather”. We find that the collision-induced trajectory shifts of waves are mainly determined by the intraspecies interactions and proportional to them in the weak nonlinearity regime. Moreover, we explore the meeting time of colliding waves and find it depends on the competition between barrier potential and atomic interactions. Particularly, we study the collisions of two waves with a slight velocity asymmetry (or with different relative phases) and the waves merging and split are demonstrated. The underlying inelastic mechanism closely related to energy exchange is briefly discussed as well.