Yong-Jian Gu

Generation of three-dimensional entangled state between a single atom and a Bose-Einstein condensate via adiabatic passage

Inspired by a recently experiment by M. Lettner et al. [Phys. Rev. Lett. 106, 210503 (2011)], we propose a robust scheme to prepare three-dimensional entanglement state between a single atom and a Bose-Einstein condensate (BEC) via stimulated Raman adiabatic passage (STIRAP) technique. The atomic spontaneous radiation, the cavity decay, and the fiber loss are efficiently suppressed by the engineering adiabatic passage. Our strictly numerical simulation shows our proposal is good enough to demonstrate the generation of three-dimensional entanglement with high fidelity and within the current experimental technology.

Generation of atomic entangled states in a bi-mode cavity via adiabatic passage

Abstract We propose schemes to prepare atomic entangled states in a bi-mode cavity via stimulated Raman adiabatic passage (STIRAP) and fractional stimulated Raman adiabatic passage (f-STIRAP) techniques. Our scheme should be realizable in the near future because of the existence of all experimental ingredients. Our numerical simulation shows we can entangle the atoms with high fidelities by choosing proper laser pulses.

Generation of NOON states via Raman transitions in a bimodal cavity

We propose a scheme for generation of NOON states via Raman transitions. In the scheme, a double

Measurement-based quantum computation with an optical two-dimensional Affleck–Kennedy–Lieb–Tasaki state

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Channel analysis for single photon underwater free space quantum key distribution

-type three-level atom is trapped in a high-Q bimodal cavity which is initially in vacuum states. After a series of operations and suitable interaction time, we can obtain highly nonclassical entangled states of one atom and N photons. Then it can easily be converted to purely photonic NOON states by application of a single projective measurement on the atom. The successful probability and fidelity of the scheme are finally discussed.

Identifying quantum states capable of high-fidelity transmission over a spin chain

The determinisitc entanglement concentration (DEC) protocol under local operations and classical communication (LOCC) for three-copy partially entangled states in bipartite systems is presented. The explicit elements of the operators used are calculated due to the general construction of the generalized measurement operator and the corresponding permutation matrices. The measurement is implemented based on the direct sum extension under the motivation to extend the initial state space with minimum number of ancillary dimensions. Morever, the concentration protocol is generalized to the DEC for n-copy multi-partite GHZ-class states. It is also pointed out that the formation of the measurement operator and the algorithms used to calculate its elements can be utilized in more general cases achieving the feasible entanglement transformation that is clarified by Nielsens theorem, such as the transformation between arbitrary bipartite states in multicopy and high-dimensional cases and so does multi-partite GHZ-class states.

A new method for quantifying entanglement of multipartite entangled states

Measurement-based quantum computation can achieve universal quantum computation via simply performing single-qubit measurements alone on an entangled resource state. Instead of the canonical resource state–cluster state, we pay great attention to another resource state, the Affleck–Kennedy–Lieb–Tasaki (AKLT) state, which is a nondegenerate ground state of a nearest-neighbor two-body interaction Hamiltonian. We propose an optical scheme to generate a two-dimensional AKLT state defined on the honeycomb lattice. In our proposal, three photons from different singlet states are projected onto a spin-32 particle comprising the AKLT state with maximum success probability 38. We also show the controlled-NOT gate can be implemented on this photonic AKLT state via projective measurement using linear optics and photodetection.

Generation of multilevel maximally entangled states under large atom-cavity detuning

Boson sampling can provide strong evidence that the computational power of a quantum computer outperforms a classical one via currently feasible linear optics experiments. However, how to identify an actual boson sampling device against any classical computing imposters is an ambiguous problem due to the computational complexity class in which boson sampling lies. The certification protocol based on bosonic bunching fails to rule out the so-called mean-field sampling. We propose a certification scheme to distinguish the boson sampling from the mean-field sampling for any random scattering matrices chosen via the Harr measure. We numerically analyze our scheme and the influence of the imperfect input states caused by non-simultaneous arrival photons.