Single-photon scattering and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system

We theoretically investigate coherent scattering of single photons and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system.Using the real-space Hamiltonian,analytical expressions are derived for the transport spectra scattered by these two giant atoms with four azimuthal angles.Fano-like resonance can be exhibited in the scattering spectra by adjusting the azimuthal angle difference.High concurrence of the entangled state for two atoms can be implemented in a wide angle-difference range,and the entanglement of the atomic states can be switched on/off by modulating the additional azimuthal angle differences from the giant atoms.This suggests a novel handle to effectively control the single-photon scattering and quantum entanglement.

Structural Foundation and Geometry of the Material Singularity (and Its Quantum Entanglement)

In this paper we develop and study, as the second part of one more general development, the energy transmutation equation for the material singularity, previously obtained through the symmetrisation of a wave packet, that is, we develop the correlation between the terms of this equation, which accounts for the formation of matter from a previous vibrational state, and the different possible energy species. These energetic species are ascribed, in a simplified form, to the equation E¯ω=E¯k+E¯f, which allows us, through its associated phase factor, to gain an insight into the wave character of the kinetic energy and thus to attain the basis of the matter-wave, and all sorts of related phenomenologies, including that concerning quantum entanglement. The formation of the matter was previously identified as an energetic process, analogous to the kinetic one, in which finally the inertial mass is consolidated as a mass in a different phase, now, in addition, the mass of the material singularity is identified as a volumetric density of waves of toroidal geometry created in the process of singularisation or energy transfer between species, which makes it possible to establish the real relation or correspondence between the corpuscular and photonic energy equation (E=mc2=hν), i.e. to explain through m the intimate sense of the first equivalence, which explains what νis in the second one.

Many-Agent Controlled Teleportation of Multi-qubit Quantum Information via Quantum Entanglement Swapping

We present a method to teleport multi-qubit quantum information in an easy way from a sender to a receiver via the control of many agents in a network. Only when all the agents collaborate with the quantum information receiver can the unknown states in the sender＇s qubits be fully reconstructed in the receiver＇s qubits. In our method, agents＇s control parameters are obtained via quantum entanglement swapping. As the realization of the many-agent controlled teleportation is concerned, compared to the recent method [G.P. Yang, et al., Phys. Rev. A 70 （2004） 022329], our present method considerably reduces the preparation difficulty of initial states and the identification difficulty of entangled states, moreover, it does not need local Hadamard operations and it is more feasible in technology.

Entanglement diversion and quantum teleportation of entangled coherent states

The proposals on entanglement diversion and quantum teleportation of entangled coherent states are presented. In these proposals, the entanglement between two coherent states, ｜α〉 and ｜-α〉, with the same amplitude but a phase difference of π is utilized as a quantum channel. The processes of the entanglement diversion and the teleportation are achieved by using the 50/50 symmctric beam splitters, the phase shifters and the photodetectors with the help of classical information.

Quantum teleportation by entanglement swapping with trapped ions

An effective teleportation scheme for an unknown ionic internal state via trapped ions is proposed without joint Bell-state measurement （BSM）. In the constructed quantum channel process, we make use of entanglement swapping to avoid decrease in entanglement during the distributing of particles. Thus our scheme provides new prospects for quantum teleportatlon in a longer distance. The distinct advant.age of our scheme is insensitive to the heating of vibrational mode. Furthermore, our scheme has no any individual optical access, and the successful probability also can reach 1.

Quantum Teleportation of One-to-Many Using （n ＋ 1）-Particle Entanglement

In this paper, quantum teleportatlon of one-to-many using （n ＋1）-particle entanglement is presented. If the sender （Alice） wants to transmit an unknown quantum state to a distant receiver （Bob）, similar to the previous schemes, Alice performs Bell-state measurement on particles belonging to herself and informs the receiver the results through the classical channel. After that, it needs to perform the Hadamard operation on the other （n - 1） particles and measure them as well. With the aid of the measurement results, Bob can operate a corresponding unitary transformation on his particle to reconstruct the original state. Of course, the reconstruction may realize at either location of n, but it cannot realize at all locations at the same time.

Bidirectional quantum teleportation of unknown photons using path-polarization intra-particle hybrid entanglement and controlled-unitary gates via cross-Kerr nonlinearity

We propose an arbitrary controlled-unitary （CU） gate and a bidirectional quantum teleportation （BQTP） scheme. The proposed CU gate utilizes photonic qubits （photons） with cross-Kerr nonlinearities （XKNLs）, X-homodyne detectors, and linear optical elements, and consists of the consecutive operation of a controlled-path （C-path） gate and a gathering-path （G- path） gate. It is almost deterministic and feasible with current technology when a strong coherent state and weak XKNLs are employed. Based on the CU gate, we present a BQTP scheme that simultaneously teleports two unknown photons between distant users by transmitting only one photon in a path-polarization intra-particle hybrid entangled state. Consequently, it is possible to experimentally implement BQTP with a certain success probability using the proposed CU gate.

Design and Implementation of Quantum Repeaters:Insights on Quantum Entanglement Purification

Quantum communication is a groundbreaking technology that is driving the future of information transmission and communication technologies to a new paradigm.It relies on quantum entanglement to facilitate the transmission of quantum states between parties.Quantum repeaters are crucial for facilitating long-distance quantum communication.These quantum devices act as intermediaries between adjacent communication channel segments within a fragmented quantum network,allowing for entanglement swapping between the channel segments.This entanglement swapping process establishes entanglement links between the endpoints of adjacent segments,gradually creating a continuous entanglement connection over the entire length of the transmission channel.The established quantum link can be utilized for secure and efficient quantum communication between distant sender and receiver nodes.This study focuses on quantum entanglement purification,a protocol aimed at maintaining high fidelity entangled states above the operational threshold of the communication channel.This study investigates the optimal stage for executing the purification protocol and applies optimization schemes to evaluate various purification protocols.We use IBM Qiskit for circuit implementation and simulation.The results offer valuable insights into future approaches to implementing practical quantum repeaters and shed light on existing and anticipated challenges.

Multi-state Quantum Teleportation via One Entanglement State

A multi-sender-controlled quantum teleportation scheme is proposed to teleport several secret quan- tum states from different senders to a distance receiver based on only one Einstein-Podolsky-Rosen (EPR) pair with controlled-NOT (CNOT) gates.In the present scheme,several secret single-qubit quantum states are encoded into a multi-qubit entangled quantum state.Two communication modes,i.e.,the detecting mode and the message mode,are employed so that the eavesdropping can be detected easily and the teleported message may be recovered efficiently.It has an advantage over teleporting several different quantum states for one scheme run with more efficiency than the previous quantum teleportation schemes.

Evaluating Qubit Control Performance by Indices of Quantum Entanglement

Entangled states are crucial to quantum computation and quantum communication, and are usually treated as the target states to be accessed by quantum control methods. While most of the researches focus on the generation of the desired entangled state at the terminal state ｜ψf〉, this paper considers the time-varying entanglement of the transient state ｜ψ（t）〉throughout the qubit transfer process. It is found that the degree of entanglement of｜ψ（t）〉 determines how fast and accurately the terminal state ｜ψf〉 can be achieved. Four quantitative indices of entanglement are employed here to evaluate the degree of entanglement of ｜ψ（t）） and to estimate the qubit control performance resulting from different control gains in the Lyapunov control law. Our results show that increasing the degree of entanglement during the qubit transfer process is helpful to improve the convergence to the target state; however, increasing control gain tends to destroy the entanglement and attenuate the multi-qubit transfer efficiency. The lack of sufficient quantum correlation between some initial state ｜ψ0〉 and terminal state is the main reason for unavailable qubit transfer between them. For these states, the insertion of an intermediate entangled state ｜ψs〉 can effectively increase the degree of entanglement and help to realize the qubit transfer ｜ψ0〉→｜ψf〉 via the transition processs ｜ψ0〉 →｜ψs〉 → ｜ψf〉.

Motion-Enhanced Quantum Entanglement in the Dynamics of Excitation Transfer

We investigate the dynamics of entanglement in the excitation transfer through a model consisting of three interacting molecules coupled to environments. It is shown that the entanglement can be further enhanced if the distance between the molecules is oscillating. Our results demonstrate that the motional effect plays a constructive role on quantum entanglement in the dynamics of excitation transfer. This mechanism might provide a useful guideline for designing artificial systems to battle against decoherence.

From E=mc^(2) to E=mc^(2)/22—A Short Account of the Most Famous Equation in Physics and Its Hidden Quantum Entanglement Origin

Einstein’s energy mass formula is shown to consist of two basically quantum components E(O) = mc2/22 and E(D) = mc2(21/22). We give various arguments and derivations to expose the quantum entanglement physics residing inside a deceptively simple expression E = mc2. The true surprising aspect of the present work is however the realization that all the involved “physics” in deriving the new quantum dissection of Einstein’s famous formula of special relativity is actually a pure mathematical necessity anchored in the phenomena of volume concentration of convex manifold in high dimensional quasi Banach spaces. Only an endophysical experiment encompassing the entire universe such as COBE, WMAP, Planck and supernova analysis could have discovered dark energy and our present dissection of Einstein’s marvelous formula.

Generation of the nonlocal quantum entanglement of three three-level particles by local operations

We propose a scheme to realize the nonlocal quantum entanglement of three three-level particles by using a threeparticle entangled state of three levels as a quantum channel with the aid of some local unitary transformations. This scheme can be directly generalized to the nonlocal quantum entanglement of N three-level particles.

Partially secret broadcasting,partially secret splitting with quantum entanglement

In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some others to multi- receivers at the same time. The efficiency of the joint protocol is also compared with that of two separate ones which realise classical secret broadcasting and classical secret splitting respectively, and based on the comparison we can see the promising advantage of our joint protocol is that it can realise the two tasks more efficiently and more conveniently.

Faithful quantum entanglement sharing based on linear optics with additional qubits

This paper presents a scheme for faithfully distributing a pure entanglement between two parties over an arbitrary collective-noise channel with linear optics. The transmission is assisted by an additional qubit against collective noise. The receiver can take advantage of the time discrimination and the measurement results of the assistant qubit to reconstruct a pure entanglement with the sender. Although the scheme succeeds probabilistically, the resource used to get a pure entanglement state is finite, and so is easier to establish entanglement in practice than quantum entanglement purification.

Comparison and control of the robustness between quantum entanglement and quantum correlation in an open quantum system

revised manuscript received 30 April 2012） We investigate the influence of environmental decoherence on the dynamics of a coupled qubit system and quantum correlation. We analyse the relationship between concurrence and the degree of initial entanglement or the purity of initial quantum state, and also their relationship with quantum discord. The results show that the decrease of the purity of an initial quantum state can induce the attenuation of concurrence or quantum discord, but the attenuation of quantum discord is obviously slower than the concurrence＇s, correspondingly the survival time of quantum discord is longer. Further investigation reveals that the robustness of quantum discord and concurrence relies on the entanglement degree of the initial quantum state. The higher the degree of entanglement, the more robust the quantum discord is than concurrence. And the reverse is equally true. Birth and death happen to quantum discord periodically and a newborn quantum discord comes into being under a certain condition, so does the concurrence.

From Modified Newtonian Gravity to Dark Energy via Quantum Entanglement

Starting from the classical Newton inverse square law of gravitation we arrive at a modified Newtonian gravity in the spirit of the work of Milgrom-Bekenstein pioneering work. This is achieved by injecting the needed quantum mechanical dissection of special relativity into Newton’s law via the modified energy mass relationship which transforms Einstein’s famous formula?from a smooth four dimensional space to a rugged fractal-like spacetime manifold. The confidence in the present result stems not only from the consistency of the mathematical scheme but also from agreement with the general direction of cosmological measurements and observations.

Study on Quantum Entanglement Between Mesoscopic Circuit and Environment at Coherent State

Taking into account the interaction between electrons and phonons, in the case without-rotating-wave aproximation, we study the entangling property between the mesoscopic circuit and environment at coherent state or equilibrium state. The result indicates that, in long time limit t →∞, the averages of charge and current in the circuit only depend on the average of the system at the initial state when the environment is initially at thermal equilibrimn. However, when the environment is initially at coherent state, the average of charge and current in the circuit is determined by the specific coherent state ensemble. Generally speaking, the entanglement between the circuit and environment will lead to the quantum state purity declining of the circuit, then the circuit emerges decoherent phenomenon, and so a mixed sta.te appears. Purity changes are related to the initial quantum state of environment and circuit. With the further evolution of time, coherence will be gradually restored, but cannot return to 1.

Reversion of weak-measured quantum entanglement state

We theoretically study the reversible process of quantum entanglement state by means of weak measurement and corresponding reversible operation.We present a protocol of the reversion operation in two bodies based on the theory of reversion of single photon and then expend it in quantum communication channels.The theoretical results demonstrate that the protocol does not break the information transmission after a weak measurement and a reversible measurement with the subsequent process in the transmission path.It can reverse the perturbed entanglement intensity evolution to its original state.Under the condition of different weak measurement intensity the protocol can reverse the perturbed quantum entanglement system perfectly.In the process we can get the classical information described by information gain from the quantum system through weak measurement operation.On the other hand,in order to realize complete reversibility,the classical information of the quantum entanglement system must obey a limited range we present in this paper in the reverse process.

Values of Siva’s Constant “<i>K</i>” for All Fundamental Forces—A Review on Spin, Threshold Time and Quantum Entanglement

Siva’s constant “K” has been explained in brief. Its numerical values have been calculated for each fundamental force of nature. Spin of quantum mechanics has been interpreted in terms of Sivas constant “K”. Thus limitation to velocity of light and interrelation between relativity and quantum mechanics has been explained in a novel and profound way. Involvement of “physics of consciousness” in synchronizing relativity and quantum mechanics has been emphasized. Concept of “bio force” as fifth fundamental force in addition to other four fundamental forces, strong, weak, electromagnetic and gravitational forces also has been emphasized. Consciousness has been explained as entanglement between bio force particle named as “jeeton” and gravitational force particle “graviton”. Thus frequency mediated consciousness has been explained.