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Lin Chen

Publications and source records attributed to Lin Chen.

574 records · Page 32Linked to original sources

Sudden death of distillability in qutrit-qutrit systems

We introduce the concept of distillability sudden death, i.e., free entangled states can evolve into non-distillable (bound entangled or separable) states in finite time under local noise. We describe the phenomenon through a specific model of local dephasing noise and compare the behavior of states in terms of the Bures fidelity. Then we propose a few methods to avoid distillability sudden death of states under (general) local dephasing noise, so that free entangled states can be robust against decoherence. Moreover, we find that bound entangled states are unstable in the limit of infinite time.

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Framed Deformation of Galois Representation

We studied framed deformations of two dimensional Galois representation of which the residue representation restrict to decomposition groups are scalars, and established a modular lifting theorem for certain cases. We then proved a family version of the result, and used it to determine the structure of deformation rings over characteristic zero fields. These can be applied to the study of exceptional zero of p-adic L-function.

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Rank three bipartite entangled states are distillable

We prove that the bipartite entangled state of rank three is distillable. So there is no rank three bipartite bound entangled state. By using this fact, We present some families of rank four states that are distillable. We also analyze the relation between the low rank state and the Werner state.

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Entanglement of formation from optimal decomposition

We present a new method of analytically deriving the entanglement of formation of the bipartite mixed state. The method realizes the optimal decomposition families of states. Our method can lead to many new results concerning entanglement of formation, its additivity and entanglement cost. We illustrate it by investigating the two-qubit state, the separable state, the maximally correlated state, the isotropic state and the Werner state.

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Symmetrized cut-join equation of Marino-Vafa formula

In this note, we symmetrized the cut-join equation from the proof of Marino-Vafa formula by applying a transcendental changing of variable. One can derive more recursion formulas of Hodge integrals out of this polynomial equations. We also give some applications.

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Multiqubit entanglement witness

We introduce a feasible method of constructing the entanglement witness that detects the genuine entanglement of a given pure multiqubit state. We illustrate our method in the scenario of constructing the witnesses for the multiqubit states that are broadly theoretically and experimentally investigated. It is shown that our method can construct the effective witnesses for experiments. We also investigate the entanglement detection of symmetric states and mixed states.

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Mixed Qubit Cannot Be Universally Broadcast

We show that there does not exist any universal quantum cloning machine that can broadcast an arbitrary mixed qubit with a constant fidelity. Based on this result, we investigate the dependent quantum cloner in the sense that some parameter of the input qubit $ρ_s(θ,ω,λ)$ is regarded as constant in the fidelity. For the case of constant $ω$, we establish the $1\to2$ optimal symmetric dependent cloner with a fidelity 1/2. It is also shown that the $1\to M$ optimal quantum cloning machine for pure qubits is also optimal for mixed qubits, when $λ$ is the unique parameter in the fidelity. For general $N\to M$ broadcasting of mixed qubits, the situation is very different.

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Asymmetric quantum telecloning of multiqubit states

We propose a scheme of 1$\to$2 optimal universal asymmetric quantum telecloning of pure multiqubit states. In particular, we first investigate the asymmetric telecloning of arbitrary 2-qubit states and then extend it to the case of multiqubit system. Many figures of merit for the telecloning process are checked, including the entanglement of the quantum channel and fidelities of the clones. Our scheme can be used for the 1$\to$4 universal telecloning of mixed multiqubit states.

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Range criterion and classification of true entanglement in $2\times{M}\times{N}$ system

We propose a range criterion which is a sufficient and necessary condition satisfied by two pure states transformable with each other under reversible stochastic local operations assisted with classical communication. We also provide a systematic method for seeking all kinds of true entangled states in the $2\times{M}\times{N}$ system, and can effectively distinguish them by means of the range criterion. The efficiency of the criterion and the method is exhibited by the classification of true entanglement in some types of the tripartite systems.

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Classification of GHZ-type, W-type and GHZ-W-type multiqubit entanglements

We propose the concept of SLOCC-equivalent basis (SEB) in the multiqubit space. In particular, two special SEBs, the GHZ-type and the W-type basis are introduced. They can make up a more general family of multiqubit states, the GHZ-W-type states, which is a useful kind of entanglement for quantum teleporatation and error correction. We completely characterize the property of this type of states, and mainly classify the GHZ-type states and the W-type states in a regular way, which is related to the enumerative combinatorics. Many concrete examples are given to exhibit how our method is used for the classification of these entangled states.

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Classification of multipartite entanglement containing infinitely many kinds of states

We give a further investigation of the range criterion and Low-to-High Rank Generating Mode (LHRGM) introduced in \cite{Chen}, which can be used for the classification of $2\times{M}\times{N}$ states under reversible local filtering operations. By using of these techniques, we entirely classify the family of $2\times4\times4$ states, which actually contains infinitely many kinds of states. The classifications of true entanglement of $2\times(M+3)\times(2M+3)$ and $2\times(M+4)\times(2M+4)$ systems are briefly listed respectively.

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Probabilistically implementing nonlocal operation using non-maximally entangled state

We develop the probabilistic implementation of a nonlocal gate $\exp{[iξ{σ_{n_A}}σ_{n_B}]}$ and $ξ\in[0,\frac\pi4]$, by using a single non-maximally entangled state. We prove that, nonlocal gates can be implemented with a fidelity greater than 79.3% and a consumption of less than 0.969 ebits and 2 classical bits, when $ξ\leq0.353$. This provides a higher bound for the feasible operation compared to the former techniques \cite{Cirac,Groisman,Bennett-1}. Besides, gates with $ξ\geq0.353$ can be implemented with the probability 79.3% and a consumption of 0.969 ebits, which is the same efficiency as the distillation-based protocol \cite{Groisman,Bennett-1}, while our method saves extra classical resource. Gates with $ξ\to0$ can be implemented with nearly unit probability and a small entanglement. We also generalize some application to the multiple system, where we find it is possible to implement certain nonlocal gates between many non-entangled partners using a non-maximally multiple entangled state.

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Remote state preparation using non-maximally entangled states

We present a scheme in which any pure qubit $|ϕ=\cosθ|0+\sinθe^{i\varp hi}|1$ could be remotely prepared by using minimum classical bits and the previously shared non-maximally entangled states, on condition that the receiver holds the knowledge of $θ$. Several methods are available to check the trade-off between the necessary entanglement resource and the achievable fidelity.

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