Generation and degree of entanglement in a relativistic formulation

2003 ◽  
Vol 3 (2) ◽  
pp. 115-120
Author(s):  
J. Pachos ◽  
E. Solano
Keyword(s):  
Quantum Electrodynamics ◽  
Charged Particles ◽  
Entangled States ◽  
Spin Interaction ◽  
Relativistic Invariance ◽  
Relativistic Formulation ◽  
Relativistic Version ◽  
Consistent Approach ◽  
Degree Of Entanglement ◽  
Dirac Spinors

The generation of entangled states and their degree of entanglement are studied in a relativistic formulation for the case of two interacting spin-1/2 charged particles. In the realm of quantum electrodynamics, we revisit the interaction that produces entanglement between the spin components of covariant Dirac spinors describing the two particles. In this way, we derive the relativistic version of the spin-spin interaction, widely used in the nonrelativistic regime. Following this consistent approach, the relativistic invariance of the generated entanglement is discussed.

scholarly journals Is Einsteinian no-signalling violated in Bell tests?

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 739-753 ◽  
Author(s):  
Marian Kupczynski
Keyword(s):  
Quantum Electrodynamics ◽  
Probability Distributions ◽  
Selection Procedure ◽  
Quantum Correlations ◽  
Spin Projection ◽  
Marginal Probability ◽  
Strong Correlations ◽  
Relativistic Invariance ◽  
Long Range Correlations ◽  
Apparent Violation

AbstractRelativistic invariance is a physical law verified in several domains of physics. The impossibility of faster than light influences is not questioned by quantum theory. In quantum electrodynamics, in quantum field theory and in the standard model relativistic invariance is incorporated by construction. Quantum mechanics predicts strong long range correlations between outcomes of spin projection measurements performed in distant laboratories. In spite of these strong correlations marginal probability distributions should not depend on what was measured in the other laboratory what is called shortly: non-signalling. In several experiments, performed to test various Bell-type inequalities, some unexplained dependence of empirical marginal probability distributions on distant settings was observed. In this paper we demonstrate how a particular identification and selection procedure of paired distant outcomes is the most probable cause for this apparent violation of no-signalling principle. Thus this unexpected setting dependence does not prove the existence of superluminal influences and Einsteinian no-signalling principle has to be tested differently in dedicated experiments. We propose a detailed protocol telling how such experiments should be designed in order to be conclusive. We also explain how magical quantum correlations may be explained in a locally causal way.

A matrix realignment method for recognizing entanglement

2003 ◽  
Vol 3 (3) ◽  
pp. 193-202
Author(s):  
K. Chen ◽  
L.-A. Wu
Keyword(s):  
Kronecker Product ◽  
Singular Values ◽  
Quantum Systems ◽  
Entangled States ◽  
Approximation Technique ◽  
Separable State ◽  
Simple Method ◽  
Bipartite Quantum Systems ◽  
The Matrix ◽  
Degree Of Entanglement

Motivated by the Kronecker product approximation technique, we have developed a very simple method to assess the inseparability of bipartite quantum systems, which is based on a realigned matrix constructed from the density matrix. For any separable state, the sum of the singular values of the matrix should be less than or equal to $1$. This condition provides a very simple, computable necessary criterion for separability, and shows powerful ability to identify most bound entangled states discussed in the literature. As a byproduct of the criterion, we give an estimate for the degree of entanglement of the quantum state.

On the gauge and relativistic invariance in quantum electrodynamics

1965 ◽  
Vol 40 (1) ◽  
pp. 319-322
Author(s):  
J. N. Chahoud ◽  
G. Russo
Keyword(s):  
Quantum Electrodynamics ◽  
Relativistic Invariance

scholarly journals METHOD OF CONSTRUCTING BRAID GROUP REPRESENTATION AND ENTANGLEMENT IN A 9 × 9 YANG–BAXTER SYSTEM

2009 ◽  
Vol 21 (09) ◽  
pp. 1081-1090 ◽  
Author(s):  
TAOTAO HU ◽  
GANGCHENG WANG ◽  
CHUNFANG SUN ◽  
CHENGCHENG ZHOU ◽  
QINGYONG WANG ◽  
...  
Keyword(s):  
Tensor Product ◽  
Braid Group ◽  
Group Representation ◽  
Standard Basis ◽  
Entangled States ◽  
Arbitrary Degree ◽  
Reducible Representation ◽  
S Matrix ◽  
Degree Of Entanglement

In this paper, we present reducible representation of the n2 braid group representation which is constructed on the tensor product of n-dimensional spaces. Specifically, it is shown that via a combining method, we can construct more n2 dimensional braiding S-matrices which satisfy the braid relations. By Yang–Baxterization approach, we derive a 9 × 9 unitary [Formula: see text]-matrix according to a 9 × 9 braiding S-matrix we have constructed. The entanglement properties of [Formula: see text]-matrix is investigated, and the arbitrary degree of entanglement for two-qutrit entangled states can be generated via [Formula: see text]-matrix acting on the standard basis.

ENTANGLEMENT DYNAMICS OF TWO QUBITS COUPLED TO SQUEEZED DISSIPATIVE ENVIRONMENTS

2010 ◽  
Vol 24 (26) ◽  
pp. 2635-2645
Author(s):  
CHUAN-JIA SHAN ◽  
TAO CHEN ◽  
JI-BING LIU ◽  
WEI-WEN CHENG ◽  
TANG-KUN LIU ◽  
...  
Keyword(s):  
Steady State ◽  
Sudden Death ◽  
Entangled States ◽  
Entanglement Sudden Death ◽  
Entanglement Dynamics ◽  
Initial Product ◽  
System Parameters ◽  
Initial States ◽  
Dissipative Environments ◽  
Degree Of Entanglement

By analytically solving the Lindblad form of the master equation, we investigate entanglement dynamics of two qubits coupled via the XY interaction, where each qubit is interacting with an independent reservoir with the squeezing parameters and squeezing angles. In the weak-squeezed reservoir, we show that the entanglement sudden death and entanglement sudden birth will happen for various entangled states. Some initial product states evolve into entangled ones, initially entangled states lose completely or partially their entanglement. The effects of varying the degree of entanglement of the initial states, the spin chain system parameters and different values of the degree of squeezing on the sudden death, revival and birth times are analyzed in detail. We also see that the steady state concurrence appears in the squeezed dissipative environments, which is affected by both the system parameters and the degree of squeezing.

Teleportation of unknown atomic entangled states via Greenberger–Horne–Zeilinger class states

2008 ◽  
Vol 86 (6) ◽  
pp. 849-851
Author(s):  
K -W Xiong
Keyword(s):  
Quantum Electrodynamics ◽  
Thermal Field ◽  
Cavity Quantum Electrodynamics ◽  
Entangled States ◽  
Quantum Channels ◽  
Cavity Decay ◽  
Maximally Entangled States

A physical scheme for teleporting unknown atomic entangled states via three-atom non-maximally entangled states is proposed in cavity quantum electrodynamics. In this scheme, the Greenberger–Horne–Zeilinger class states are used as quantum channels. The most distinct feature of our scheme is that, not only the effects of the cavity decay and thermal field are eliminated, but also the teleportation and distillation procedure can be realized simultaneously.PACS Nos.: 03.67.Hk, 03.67.Pp

Dynamics of multi-qubit states in non-inertial frames for quantum communication applications

2014 ◽  
Vol 14 (3&4) ◽  
pp. 255-264
Author(s):  
Alaa Sagheer ◽  
Hala Hamdoun
Keyword(s):  
Degradation Rate ◽  
Quantum Communication ◽  
Ghz State ◽  
The Other ◽  
W State ◽  
Entangled States ◽  
Inertial Frames ◽  
Qubit States ◽  
Degree Of Entanglement ◽  
Accelerated Frames

In this paper, some properties of multi-qubit states traveling in non-inertial frames are investigated, where we assume that all particles are accelerated. These properties are including fidelities, capacities and entanglement of the accelerated channels for three different states, namely, Greeberger-Horne-Zeilinger (GHZ) state, GHZ-like state and W-state. It is shown here that all these properties are decreased as the accelerations of the moving particles are increased. The obtained results show that the GHZ-state is the most robust state comparing to the others, where the degradation rate is less than that for the other states particularly in the second Rindler region. Also, it is shown here that the entangled property doesn't change in the accelerated frames. Additionally, the paper shows that the degree of entanglement decreases as the accelerations of the particles increase in the first Rindler region. However in the second region, where all subsystems are disconnected at zero acceleration, entangled states are generated as the acceleration increases.

scholarly journals MASS RENORMALIZATION IN NON-RELATIVISTIC QUANTUM ELECTRODYNAMICS WITH SPIN ½

2007 ◽  
Vol 19 (04) ◽  
pp. 405-454 ◽  
Author(s):  
F. HIROSHIMA ◽  
K. R. ITO
Keyword(s):  
Effective Mass ◽  
Explicit Form ◽  
Quantum Electrodynamics ◽  
Relativistic Quantum ◽  
Spin Interaction ◽  
Bare Mass ◽  
Coupling Constant ◽  
Mass Renormalization ◽  
Ultraviolet Cutoff ◽  
Constant E

The effective mass m eff of the Pauli–Fierz Hamiltonian with ultraviolet cutoff Λ and the bare mass m in non-relativistic quantum electrodynamics (QED) with spin ½ is investigated. Analytic properties of m eff in coupling constant e are shown. Let us set [Formula: see text]. The explicit form of constant a2(Λ/m) depending on Λ/m is given. It is shown that the spin interaction enhances the effective mass and that there exist strictly positive constants c1 and c2 such that [Formula: see text] In particular though it is known that a1(Λ/m) diverge log (Λ/m) as Λ → ∞, a2(Λ/m) does not diverge as ± [ log (Λ/m)]2 but -(Λ/m)2.

Sign in / Sign up

Export Citation Format

Share Document