Bidirectional Controlled Teleportation by Using 5-Qubit States: A Generalized View

Recently bidirectional controlled perfect teleportation using 5-qubit states are reported in Int. J. Theor. Phys. (2013), doi:10.1007/s10773-013-1484-8 and ibid (2012), doi:10.1007/s10773-012-1208-5. In this paper we have shown that there exists a class of 5-qubit quantum states that can be used for bidirectional controlled teleportation. Two out of the three reported cases are the special cases of the proposed class of 5-qubit quantum states and one of them is not strictly a case of controlled bidirectional quantum teleportation. Further, we have shown that one can in principle, construct infinitely many 5-qubit quantum states for this purpose. We have also shown that the idea can be extended to bidirectional controlled probabilistic teleportation. Some potential applications of the proposed scheme and its modified versions are also discussed in relation with the implementation of quantum remote control and quantum cryptography.     

Modification Attack on QSDC with Authentication and the Improvement

Recently, Yu et al. [Int. J. Theor. Phys., 2012, doi:10.1007/s10773-012-1336-y] proposed a quantum secure direct communication (QSDC) with authentication using two non-orthogonal states. This study points out a pitfall in Yu et al.’s scheme, in which an eavesdropper can deliberately modify the message without being detected. Furthermore, an enhanced scheme is proposed to avoid the modification attack.     

Man-in-the-Middle Attack on “Quantum Dialogue with Authentication Based on Bell States”

Recently, Shen et al. (Int. J. Theor. Phys. doi:10.1007/s10773-012-1276-6, 2012) proposed a quantum dialogue with authentication protocol based on Bell states. This study points out that Shen et al.’s protocol suffers from a man-in-the-middle attack. By manipulating the photons and classical information transmitted between two communicants, an attacker can not only pass the mutual identity authentication, but also obtain their secret messages and new authentication keys without being detected.     

Dynamic Logic Assigned to Automata

A dynamic logic B can be assigned to every automaton Open image in new window without regard if Open image in new window is deterministic or nondeterministic. This logic enables us to formulate observations on Open image in new window in the form of composed propositions and, due to a transition functor T, it captures the dynamic behaviour of Open image in new window . There are formulated conditions under which the automaton Open image in new window can be recovered by means of B and T.     

Fractional quiver W-algebras

We introduce quiver gauge theory associated with the non-simply laced type fractional quiver and define fractional quiver W-algebras by using construction of Kimura and Pestun (Lett Math Phys, 2018.  https://doi.org/10.1007/s11005-018-1072-1; Lett Math Phys, 2018.  https://doi.org/10.1007/s11005-018-1073-0) with representation of fractional quivers.     

Some Exact Relativistic Models of Electrically Charged Self-bound Stars

In continuation of recent work done by the present authors (Int. J. Theor. Phys. 2013, doi:10.1007/s10773-013-1538-y, hereafter paper I) some new exact families of static spherically symmetric perfect fluid solution of Einstein–Maxwell gravitational field equations are presented. These solutions and the corresponding equations of state, presented in parametric form, may be astrophysically significant in constructing relativistic stellar models of electrically charged self-bound stars.     

Quantum Locality,Rings a Bell?: Bell’s Inequality Meets Local Reality and True Determinism

By assuming a deterministic evolution of quantum systems and taking realism into account, we carefully build a hidden variable theory for Quantum Mechanics (QM) based on the notion of ontological states proposed by ’t Hooft (The cellular automaton interpretation of quantum mechanics, arXiv:1405.1548v3, 2015; Springer Open 185,  https://doi.org/10.1007/978-3-319-41285-6, 2016). We view these ontological states as the ones embedded with realism and compare them to the (usual) quantum states that represent superpositions, viewing the latter as mere information of the system they describe. Such a deterministic model puts forward conditions for the applicability of Bell’s inequality: the usual inequality cannot be applied to the usual experiments. We build a Bell-like inequality that can be applied to the EPR scenario and show that this inequality is always satisfied by QM. In this way we show that QM can indeed have a local interpretation, and thus meet with the causal structure imposed by the Theory of Special Relativity in a satisfying way.     

Kinematical Implications of a New f(R) Theory of Gravity: The Redshift

In this paper, we discuss the kinematical concepts of a recently defined f(R) action (Payandeh and Fathi in Int. J. Theor. Phys., 2013, doi:10.1007/s10773-013-1770-5). Firstly, we retreat the action to obtain the kinematic representation of the standard cosmology components, and then, we go through our model, to find the cosmological redshift, according to the scalar field constituents of the theory.     

A Hierarchical Modulation Coherent Communication Scheme for Simultaneous Four-State Continuous-Variable Quantum Key Distribution and Classical Communication

We present a hierarchical modulation coherent communication protocol, which simultaneously achieves classical optical communication and continuous-variable quantum key distribution. Our hierarchical modulation scheme consists of a quadrature phase-shifting keying modulation for classical communication and a four-state discrete modulation for continuous-variable quantum key distribution. The simulation results based on practical parameters show that it is feasible to transmit both quantum information and classical information on a single carrier. We obtained a secure key rate of \(10^{-3}\) bits/pulse to \(10^{-1}\) bits/pulse within 40 kilometers, and in the meantime the maximum bit error rate for classical information is about \(10^{-7}\). Because continuous-variable quantum key distribution protocol is compatible with standard telecommunication technology, we think our hierarchical modulation scheme can be used to upgrade the digital communication systems to extend system function in the future.     

Connecting the Kontsevich-Witten and Hodge Tau-functions by the {\widehat{GL(\infty)}} Operators

In this paper, we present an explicit formula that connects the Kontsevich-Witten tau-function and the Hodge tau-function by differential operators belonging to the \({\widehat{GL(\infty)}}\) group. Indeed, we show that the two tau-functions can be connected using Virasoro operators. This proves a conjecture posted by Alexandrov in (From Hurwitz numbers to Kontsevich-Witten tau-function: a connection by Virasoro operators, Letters in Mathematical physics, doi:10.1007/s11005-013-0655-0, 2014).     

A third-order approximation for time delay of light propagation in the equatorial plane of Kerr black hole

The rotation effect of the gravitational source such as Kerr black hole on the time delay of light propagation has been studied in detail. Although it belongs to the second order, the magnitude of rotation effect may be smaller than that of the third-order effect of mass. In this paper, we calculate the time delay of the propagation of light in the equatorial plane of a Kerr black hole to the third order analytically. It is found that the third-order effect of mass is larger than the rotation effect when the magnitude of impact factor $|b| < \frac{120-5\pi }{16}\frac{M^3}{J}+M$ , with $M$ and $J$ being the mass and angular momentum of black hole. The total third-order effects on the time delay are also examined.     

EPR study of carbonate derived and ozonide radicals in carbonated apatites synthesized from aqueous solutions

In this study, a series of Na⁺ and¹²CO ₃ ^2? containing apatites synthesized by a hydrolysis of octo-calciumphosphate (OCP) and dried at 25°C until constant weight, were examined with EPR after X-irradiation. A variety of different paramagnetic radicals was formed, giving rise to composite and hence complex EPR powder spectra. The spectra were successfully decomposed into their basic components using a multivariate statistical technique. The different components could be identified unambiguously. In this way, it was found that an O^?, an O ₃ ^? , a CO ₃ ^? , two types of CO ₂ ^? and two types of CO ₃ ^3? ions were formed upon X-irradiation. Also resonances from atomic hydrogen were observed. The most striking feature is the presence of the ozonide ion, which is only rarely observed in irradiated hydroxyapatites. A comparison is made between the EPR spectra of apatite samples prepared by hydrolysis of OCP on the one hand, and those of samples prepared by hydrolyzing monetite, and the tooth enamel spectrum on the other hand.     

Temperature Effect of Hydrogen-Like Impurity on the Ground State Energy of Strong Coupling Polaron in a RbCl Quantum Pseudodot

We study the ground state energy and the mean number of LO phonons of the strong-coupling polaron in a RbCl quantum pseudodot (QPD) with hydrogen-like impurity at the center. The variations of the ground state energy and the mean number of LO phonons with the temperature and the strength of the Coulombic impurity potential are obtained by employing the variational method of Pekar type and the quantum statistical theory (VMPTQST). Our numerical results have displayed that the absolute value of the ground state energy increases (decreases) when the temperature increases at lower (higher) temperature regime, the mean number of the LO phonons increases with increasing temperature, the absolute value of ground state energy and the mean number of LO phonons are increasing functions of the strength of the Coulombic impurity potential.     

Brick walls and AdS/CFT

We discuss the relationship between the bulk-boundary correspondence in Rehren’s algebraic holography (and in other ‘fixed-background’, QFT-based, approaches to holography) and in mainstream string-theoretic ‘Maldacena AdS/CFT’. Especially, we contrast the understanding of black-hole entropy from the point of view of QFT in curved spacetime—in the framework of ’t Hooft’s ‘brick wall’ model—with the understanding based on Maldacena AdS/CFT. We show that the brick-wall modification of a Klein–Gordon field in the Hartle–Hawking–Israel state on $1+2$ dimensional Schwarzschild AdS has a well-defined boundary limit with the same temperature and entropy as the brick-wall-modified bulk theory. One of our main purposes is to point out a close connection, for general AdS/CFT situations, between the puzzle raised by Arnsdorf and Smolin regarding the relationship between Rehren’s algebraic holography and mainstream AdS/CFT and the puzzle embodied in the ‘complementarity principle’ proposed by Mukohyama and Israel in their work on the brick-wall approach to black hole entropy. Working on the assumption that similar results will hold for bulk QFT other than the Klein–Gordon field and for Schwarzschild AdS in other dimensions, and recalling the first author’s proposed resolution to the Mukohyama–Israel puzzle based on his ‘matter–gravity entanglement hypothesis’, we argue that, in Maldacena AdS/CFT, the algebra of the boundary CFT is isomorphic only to a proper subalgebra of the bulk algebra, albeit (at non-zero temperature) the (GNS) Hilbert spaces of bulk and boundary theories are still the ‘same’—the total bulk state being pure, while the boundary state is mixed (thermal). We also argue from the finiteness of its boundary (and hence, on our assumptions, also bulk) entropy at finite temperature, that the Rehren dual of the Maldacena boundary CFT cannot itself be a QFT and must, instead, presumably be something like a string theory.     

Some conservative estimates in quantum cryptography

Relationship is established between the security of the BB84 quantum key distribution protocol and the forward and converse coding theorems for quantum communication channels. The upper bound Q _c ≈ 11% on the bit error rate compatible with secure key distribution is determined by solving the transcendental equation $H(Q_c ) = \bar C(\rho )/2$ , where ρ is the density matrix of the input ensemble, $\bar C(\rho )$ is the classical capacity of a noiseless quantum channel, and H(Q) is the capacity of a classical binary symmetric channel with error rate Q.     

On the effective field theory of heterotic vacua

The effective field theory of heterotic vacua that realise Open image in new window preserving \(\mathcal {N}{=}1\) supersymmetry is studied. The vacua in question admit large radius limits taking the form Open image in new window , with Open image in new window a smooth threefold with vanishing first Chern class and a stable holomorphic gauge bundle Open image in new window . In a previous paper we calculated the kinetic terms for moduli, deducing the moduli metric and Kähler potential. In this paper, we compute the remaining couplings in the effective field theory, correct to first order in \({\alpha ^{\backprime }\,}\). In particular, we compute the contribution of the matter sector to the Kähler potential and derive the Yukawa couplings and other quadratic fermionic couplings. From this we write down a Kähler potential Open image in new window and superpotential Open image in new window .     

An Efficient and Secure Arbitrary <Emphasis Type="Italic">N</Emphasis>-Party Quantum Key Agreement Protocol Using Bell States

Two quantum key agreement protocols using Bell states and Bell measurement were recently proposed by Shukla et al. (Quantum Inf. Process. 13(11), 2391–2405, 2014). However, Zhu et al. pointed out that there are some security flaws and proposed an improved version (Quantum Inf. Process. 14(11), 4245–4254, 2015). In this study, we will show Zhu et al.’s improvement still exists some security problems, and its efficiency is not high enough. For solving these problems, we utilize four Pauli operations {I, Z, X, Y} to encode two bits instead of the original two operations {I, X} to encode one bit, and then propose an efficient and secure arbitrary N-party quantum key agreement protocol. In the protocol, the channel checking with decoy single photons is introduced to avoid the eavesdropper’s flip attack, and a post-measurement mechanism is used to prevent against the collusion attack. The security analysis shows the present protocol can guarantee the correctness, security, privacy and fairness of quantum key agreement.     

Motions of vortex patches

An evolution equation describing the motion of vortrex patches is established. The existence of steady solutions of this equation is proved. These solutions arem-fold symmetric regions of constant vorticity ω₀ and are uniformly rotating with angular velocity Ω in the range $$\tilde \Omega _{m - 1}< \tilde \Omega \leqslant \tilde \Omega _m (\tilde \Omega = \Omega /\omega _0 ,m \geqslant 2)$$ where \(\tilde \Omega _m = (m - 1)/2m\) . We call this class, ofm-fold symmetric rotating regionsD, the class of them-waves of Kelvin. Any may be regarded as a simply connected region which is a stationary configuration of the Euler equations in two dimensions. If then any magnification, rotation or reflection is also in with the same angular velocity Ω ofD. The angular velocity \(\Omega _m = \tilde \Omega _m \omega _0 \) corresponds only to the circle solution, which is a trivial member of every class ,m?2. The class corresponds to the rotating ellipses of Kirchoff. Other properties of the class are established.     

New Probabilistic Quantum Key Distribution Protocol

On the basis of entanglement swapping of Bell states, Hwang et al. proposed a probabilistic quantum key distribution (PQKD) protocol Quantum Inf. Comput. 11(7-8), 615–637 (2011). Recently, Lin et al. Quantum Inf. Comput. 14(9-10), 757–762 (2014) proposed a unitary operation attack on Hwang et al.’s PQKD. However, unlike the unitary operation attack, this work points out that a malicious participant in Hwang et al.’s PQKD protocol can manipulate the secret key. As a result, the security requirements of a PQKD protocol, i.e., fairness, cannot be satisfied in their protocol. Moreover, the same attack can also crack the fairness requirement of the existing quantum key agreement (QKA) protocols. To overcome both problems, this paper proposes a new PQKD protocol based on the order rearrangement of the transmitted photons. Furthermore, the rearrangement method can also solve the key manipulation attack in QKA protocols.