Z. Xu

Quantum computation based on d-level cluster state

The concept of a qudit (a d-level system) cluster state is proposed by generalizing the qubit cluster state [Phys. Rev. Lett. 86, 910 (2001)] to higher-dimensional Hilbert space according to the finite-dimensional representations of quantum plane algebra. We demonstrate their quantum correlations and prove a theorem which guarantees the availability of the qudit cluster states in quantum computation. We explicitly construct the network to show the universality of the one-way computer based on the defined qudit cluster states and single-qudit measurement. A protocol of implementing one-way quantum computer is suggested using the high-dimensional Ising model which can be found in many magnetic systems.

Entanglement properties of some fractional quantum Hall liquids

We study the entanglement properties of some fractional quantum Hall liquids. We calculate the entanglement of the Laughlin wave function and the wave functions that are generated by the K matrix using the modified entanglement measure of indistinguishable fermions that is first proposed by Paifmmode check{s}else v{s}fi{}kauskas and You [Phys. Rev. A64, 042310 (2001)].

Multiparty correlation measure based on the cumulant

A magnetically trapped atom experiences an adiabatic geometric (Berrys) phase due to changing field direction. We investigate theoretically such an Aharonov-Bohm-like geometric phase for atoms adiabatically moving inside a storage ring as demonstrated in several recent experiments. Our result shows that this phase shift is easily observable in a closed loop interference experiment, and thus the shift has to be accounted for in the proposed inertial sensing applications. The spread in phase shift due to the atom transverse distribution is quantified through numerical simulations.

Effective size of a trapped atomic Bose gas

We investigate the temperature-dependent effective size of a trapped interacting atomic Bose gas within a mean field theory approximation. The sudden shrinking of the average length, as observed in an earlier experiment by Wang et al. [Chin. Phys. Lett. 20, 799 (2003)], is shown to be a good indication for Bose-Einstein condensation. Our study also supports the use of the average width of a trapped Bose gas for a nondestructive calibration of its temperature.

Skyrmion excitation in a two-dimensional spinor Bose-Einstein condensate

We study the properties of coreless vortices (skyrmions) in spinor Bose-Einstein condensates. We find that this excitation is always energetically unstable, it always decays to an uniform spin texture. We obtain the skyrmion energy as a function of its size and position, a key quantity in understanding the decay process. We also point out that the decay rate of a skyrmion with high winding number will be slower. The interaction between skyrmions and other excitation modes are also discussed.

Entanglement and spin-squeezing properties for three bosons in two modes

We discuss the canonical form for a pure state of three identical bosons in two modes, and classify its entanglement correlation into two types, the analogous Green-Horne-Zeilinger and the

Quantum spin mixing in a binary mixture of spin-1 atomic condensates

W

Quantum entangled ground states of two spinor Bose-Einstein condensates

types as well known in systems of three distinguishable qubits. We have performed a detailed study of two important entanglement measures for such a system, the concurrence

Atomic number fluctuations in a mixture of two spinor condensates

mathcal{C}

Encoding a logical qubit into physical qubits

and the triple entanglement measure