arXiv subjects

Yi-Xin Chen

Publications and source records attributed to Yi-Xin Chen.

At least 55 records · Page 3Linked to original sources

arXiv2009

Disk relations for tree amplitudes in minimal coupling theory of gauge field and gravity

KLT relations on $S_2$ factorize closed string amplitudes into product of open string tree amplitudes. The field theory limits of KLT factorization relations hold in minimal coupling theory of gauge field and gravity. In this paper, we consider the field theory limits of relations on $D_2$. Though the relations on $D_2$ and KLT factorization relations hold on worldsheets with different topologies, we find the field theory limits of $D_2$ relations also hold in minimal coupling theory of gauge field and gravity. We use the $D_2$ relations to give three- and four-point tree amplitudes where gluons are minimally coupled to gravitons. We also give a discussion on general tree amplitudes for minimal coupling of gauge field and gravity. In general, any tree amplitude with $M$ gravitons in addition to $N$ gluons can be given by pure-gluon tree amplitudes with $N+2M$ legs.

hep-th↗

arXiv2009

Quantum correlations in topological quantum phase transitions

We study the quantum correlations in a 2D system that possesses a topological quantum phase transition. The quantumness of two-body correlations is measured by quantum discord. We calculate both the correlation of two local spins and that of an arbitrary spin with the rest of the lattice. It is notable that local spins are classically correlated, while the quantum correlation is hidden in the global lattice. This is different from other systems which are not topologically orderd. Moreover, the mutual information and global quantum discord show critical behavior in the topological quantum phase transition.

quant-ph↗

arXiv2009

Relations Between Closed String Amplitudes at Higher-order Tree Level and Open String Amplitudes

KLT relations almost factorize closed string amplitudes on $S_2$ by two open string tree amplitudes which correspond to the left- and the right- moving sectors. In this paper, we investigate string amplitudes on $D_2$ and $RP_2$. We find that KLT factorization relations do not hold in these two cases. The relations between closed and open string amplitudes have new forms. On $D_2$ and $RP_2$, the left- and the right- moving sectors are connected into a single sector. Then an amplitude with closed strings on $D_2$ or $RP_2$ can be given by one open string tree amplitude except for a phase factor. The relations depends on the topologies of the world-sheets.Under T-duality, the relations on $D_2$ and $RP_2$ give the amplitudes between closed strings scattering from D-brane and O-plane respectively by open string partial amplitudes.In the low energy limits of these two cases, the factorization relations for graviton amplitudes do not hold. The amplitudes for gravitons must be given by the new relations instead.

hep-th↗

arXiv2009

Information loss and entropy conservation in quantum corrected Hawking radiation

It was found in [Phys.Lett.B 675 (2009) 98] that information is conserved in the process of black hole evaporation, by using the tunneling formulism and considering the correlations between emitted particles. In this Letter, we shall include quantum gravity effects, by taking into account of the log-area correction to Bekenstein-Hawking entropy. The correlation between successively emitted particles is calculated, with Planck-scale corrections. By considering the black hole evaporation process, entropy conservation is checked, and the existence of black hole remnant is emphasized. We conclue in this case information can leak out through the radiation and black hole evaporation is still a unitary process.

hep-th↗

arXiv2009

Relativistic Theory of Infinite Statistics Fields

Infinite statistics in which all representations of the symmetric group can occur is known as a special case of quon theory. However, the validity of relativistic quon theories is still in doubt. In this paper we prove that there exists a relativistic quantum field theory which allows interactions involving infinite statistics particles. We also give some consistency analysis of this theory such as conservation of statistics and Feynman rules.

hep-th↗

arXiv2009

Supersymmetric black rings and non-linear sigma models

In this paper we investigate the non-linear sigma model arising in the reduction of D = 5 supergravity to D = 3, and present the application of this sigma model to supersymmetric black ring solutions in five-dimensional minimal supergravity. With the ansatz of stationary solutions with $R \times U(1)\times U(1)$ isometry, we obtain a two-dimensional Lagrangian corresponding to geodesic motion of a string-like object on the coset $G_{2(+2)}/SO(4)$, and study the algebra of conserved charges and supersymmetry constraints of supersymmetric black rings. We also obtain the semi-classical wave function of supersymmetric black rings.

hep-th↗

arXiv2008

Large Extra Dimensions and Holography

The holographic principle asserts that the entropy of a system cannot exceed its boundary area in Planck units. However, conventional quantum field theory fails to describe such systems. In this Letter, we assume the existence of large $n$ extra dimensions and propose a relationship between UV and IR cutoffs in this case. We find that if $n=2$, this effective field theory could be a good description of holographic systems. If these extra dimensions are detected in future experiments, it will help to prove the validity of the holographic principle. We also discuss implications for the cosmological constant problem.

hep-th↗

arXiv2008

Space-time uncertainty relation from quantum and gravitational principles

By collecting both quantum and gravitational principles, a space-time uncertainty relation $(δt)(δr)^{3}\geqslantπr^{2}l_{p}^{2}$ is derived. It can be used to facilitate the discussion of several profound questions, such as computational capacity and thermodynamic properties of the universe and the origin of holographic dark energy. The universality and validity of the proposed relation are illustrated via these examples.

hep-th↗

arXiv2008

Covariant versions of Margolus-Levitin Theorem

The Margolus-Levitin Theorem is a limitation on the minimal evolving time of a quantum system from its initial state to its orthogonal state. It also supplies a bound on the maximal operations or events can occur within a volume of spacetime. We compare Margolus-Levitin Theorem with other form of limitation on minimal evolving time, and present covariant versions of Margolus-Levitin Theorem in special and general relativity respectively. The relation among entropy bound, maximum information flow and computational limit are discussed, by applying the covariant versions of Margolus-Levitin Theorem.

hep-th↗

arXiv2008

The Entropy Bound for Local Quantum Field Theory

We investigate the entropy bound for local quantum field theory in this paper. Both the bosonic and fermionic fields confined to an asymptotically flat spacetime are examined. By imposing the non-gravitational collapse condition, we find both of them are limited by the same entropy bound $A^{3/4}$, where $A$ is the boundary area of the region where the quantum fields are contained in. The gap between this entropy bound and the holographic entropy has been verified.

hep-th↗

arXiv2008

Black hole hair in higher dimensions

We study the property of matter in equilibrium with a static, spherically symmetric black hole in D-dimensional spacetime. It requires this kind of matter has an equation of state (ω\equiv p_r/ρ=-1/(1+2kn), k,n\in \mathbb{N}), which seems to be independent of D. However, when we associate this with specific models, some interesting limits on space could be found: (i)(D=2+2kn) while the black hole is surrounded by cosmic strings; (ii)the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D=4 is special.

hep-th↗

arXiv2008

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.

quant-ph↗

arXiv2008

First-order attractor flow equations for supersymmetric black rings in N=2, D=5 supergravity

In this paper we investigate the attractor mechanism in the five dimensional low energy supergravity theory corresponding to M-theory compactified on a Calabi-Yau threefold $CY_3$. Using very special geometry, we derive the general first-order attractor flow equations for BPS and non-BPS solutions in five-dimensional Gibbons-Hawking spaces. Especially, considering the supersymmetric solution, we obtain the first-order flow equations for supersymmetric (multi)black rings. We also solve the flow equations and discuss some properties of the solutions of flow equations.

hep-th↗

arXiv2007

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.

quant-ph↗

arXiv2007

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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arXiv2006

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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arXiv2006

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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arXiv2006

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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