Quantum state transfer between atomic ensembles trapped in separate cavities via adiabatic passage

We propose a new approach for quantum state transfer（QST） between atomic ensembles separately trapped in two distant cavities connected by an optical fiber via adiabatic passage. The three-level Λ-type atoms in each ensemble dispersively interact with the nonresonant classical field and cavity mode. By choosing appropriate parameters of the system, the effective Hamiltonian describes two atomic ensembles interacting with ＂the same cavity mode＂ and has a dark state. Consequently, the QST between atomic ensembles can be implemented via adiabatic passage. Numerical calculations show that the scheme is robust against moderate fluctuations of the experimental parameters. In addition, the effect of decoherence can be suppressed effectively. The idea provides a scalable way to an atomic-ensemble-based quantum network, which may be reachable with currently available technology.

Quantum state swap for two trapped Rydberg atoms

The quantum swap gate is one of the most useful gates for quantum computation. Two-qubit entanglement and a controlled-NOT quantum gate in a neutral Rydberg atom system have been achieved in recent experiments. It is therefore very interesting to propose a scheme here for swapping a quantum state between two trapped neutral atoms via the Rydberg blockade mechanism. The atoms interact with a sequence of laser pulses without individual addressing. The errors of the swap gate due to imprecision of pulse length, finite Rydberg interaction, and atomic spontaneous emission are discussed.

Simplified Protocol of Quantum Teleportation

A simplified version of the quantum teleportation protocol is presented in here. Its experimental confirmation will have deep implications for a better understanding of Quantum Entanglement with a particular projection on Quantum Communications.

Enhanced sensing of anharmonicities in a gain-based anti-PT symmetric system

We study the enhanced sensing of weak anharmonicities in a gain-based cavity-magnon-waveguide coupled system.By dissipatively coupling the two subsystems through a mediating waveguide,the Hamiltonian of the system is tailored to be anti-parity-time symmetric.Unique to the gain condition,the eigenvalues exhibit two singularities with linewidth suppression,distinguishing them from those of gain-free systems.Under the gain condition,a counter-intuitive bistable signature emerges even at low drive powers.As the effective gain approaches a certain value,this bistability yields a significantly enhanced spin-current response of the magnon mode.Consequently,the sensitivity,quantified by an enhancement factor,is enhanced remarkably compared to the linewidth suppression scenario.Moreover,the high enhancement factor can be sustained over a broad gain-bandwidth and also stays large even when the coherent coupling becomes considerably strong.Based on the integrated cavity-magnon-waveguide systems,this scheme can be used for sensing different physical quantities related to the Kerr-type nonlinearity and has potential applications in high-precision measuring microwave-signal nonlinearities.

Generation of four-atom Greenberger-Horn-Zeilinger state via adiabatic passage

We propose a scheme to generate a Greenberger-Horn-Zeilinger （GHZ） state of four atoms trapped in a two-mode optical cavity via an adiabatic passage. The scheme is robust against moderate fluctuations of the experimental parameters. Numerical calculations show that the excited probabilities of both the cavity modes and the atoms are tiny and depend on the pulse peaks of the classical laser fields. For certain decoherence due to the atomic spontaneous emission and the cavity decay, there exits a range of pulse peaks to get a high fidelity.

Engineering steady-state entanglement for two atoms held in separate cavities through laser cooling

We propose a scheme to prepare the steady-state entanglement for two atoms, which are held in separate cavities that are coupled through a short optical fiber or optical resonator. The entangled steady-state with a high fidelity can be achieved even with a low cooperativity parameter, by making use of the driving laser fields. Such a cooling mechanism is based on a resonant laser pump of the unwanted ground states to the excited states, which finally decay to the desired steady-state.

Robust Generation of Qutrit-Qutrit Entanglement through a Single Resonant Interaction Assisted by Moderate Driving

We propose to engineer qutrit-qutrit entanglement through resonant atom-cavity interaction assisted by moderate laser driving,study two parameter regimes,respectively,of asymmetric atom-laser coupling and of asymmetric atom-cavity coupling,and find that both the coupling regimes possess the advantage of short operation time,compared with the previous ones achieved by dispersive interaction,adiabatic passage,and even quantum Zeno dynamics.We check numerically the influences of the parameter fluctuations and dissipation on the scheme and show it to be robust.The scheme can also be generalized to other physical systems such as the ion trap.

Distributed Qutrit-Qutrit Entanglement through Laser-Driven Resonant Interaction

We propose to deterministically realize the qutrit-qutrit maximal entanglement for two atoms held in separate cavities coupled by an optical resonator. We study such a system in the resonant regime and show that the laser-driven resonant dynamics allow for the fast and robust creation of qutrit-qutrit entanglement.

Cluster-cracking Reaction, a New Method to Synthesize Unsymmetrical Dithiolate Complexes for the Study of Third-Order Nonlinear Optical Properties

A new cluster-cracking method to synthesize dithiolate metal complexes was reported and four unsymmetric complexes with formula (Me4N)(2)[M(Ln)(SPh)(2)] (M = Cd and Zn, L1 = dmit = 1, 3-dithiole-2-thione-4, 5-dithiolate, L2 = dmid = 1, 3-dithiole-2-one-4, 5-dithiolate, SPh = thiophenolate) (1-4) were characterized by, elemental analysis, ER, UV NMR spectra and so on. The advantages of this method am summarized in two aspects: (1) the preparation is very convenient; (2) the reaction usually completed giving the product with high,purity. The crystal structure of 1 showed that the bond distances of Cd(II) to the sulfur of the thiophenolate group are shorter than those of Cd(II) to the sulfur of dmit, so that the thiophenolate group does not be replaced in the reaction and the mixed ligand complexes are the dominant products. The dmit complexes showed well third-order NLO properties, but not of the dmid complexes, although druid is an analogue to dmit.

Fast spin squeezing by distance-selective long-range interactions with Rydberg molecule dressing

We propose a Rydberg molecule dressing scheme to create strong and long-ranged interactions at selective distances. This is achieved through laser coupling ground-state atoms off-resonantly to an attractive molecular curve of two interacting Rydberg atoms. Although dephasing due to Rydberg state decay occurs in all dressing schemes, an advantage of the molecule dressing is that a large ratio of dressed interaction to dephasing rate can be realized at large atomic separations. In an optical lattice or tweezer setting, we show that the strong interaction permits the fast generation of spin squeezing for several tens of dressed atoms.The proposed setting offers a new route to study complex many-body dynamics and to realize quantum information processing with non-convex long-range interactions.