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K. V. Antipin

Publications and source records attributed to K. V. Antipin.

12 recordsLinked to original sources
arXiv2023

On generating r-uniform subspaces with the isometric mapping method

We propose a compositional approach to construct subspaces consisting entirely of r-uniform states, including the ones in heterogeneous systems. The approach allows one to construct new objects from old ones: it combines encoding isometries of pure quantum error correcting codes with entangled multipartite states and subspaces. The presented methods can be also used to construct new pure quantum error correcting codes from certain combinations of old ones. The approach is illustrated with various examples including constructions of 2-, 3-, 4-, 5-uniform subspaces. The results are then compared with analogous constructions obtained with the use of orthogonal arrays.

quant-ph↗
arXiv2022

Construction of genuinely entangled multipartite subspaces from bipartite ones by reducing the total number of separated parties

Construction of genuinely entangled multipartite subspaces with certain characteristics has become a relevant task in various branches of quantum information. Here we show that such subspaces can be obtained from an arbitrary collection of bipartite entangled subspaces under joining of their adjacent subsystems. In addition, it is shown that direct sums of such constructions under certain conditions are genuinely entangled. These facts are then used in detecting entanglement of tensor products of mixed states and constructing subspaces that are distillable across every bipartite cut, where for the former application we include example with the analysis of genuine entanglement of a tripartite state obtained from two Werner states.

quant-ph↗
arXiv2021

Construction of genuinely multipartite entangled subspaces and the associated bounds on entanglement measures for mixed states

Genuine entanglement is the strongest form of multipartite entanglement. Genuinely entangled pure states contain entanglement in every bipartition and as such can be regarded as a valuable resource in the protocols of quantum information processing. A recent direction of research is the construction of genuinely entangled subspaces -- the class of subspaces consisting entirely of genuinely multipartite entangled pure states. In this paper we present several methods of construction of such subspaces including those of maximal possible dimension. The approach is based on the correspondence between bipartite entangled subspaces and quantum channels of a certain type. The examples include maximal subspaces for systems of three qubits, four qubits, three qutrits. We also provide lower bounds on two entanglement measures for mixed states, the concurrence and the convex-roof extended negativity, which are directly connected with the projection on genuinely entangled subspaces.

quant-ph↗
arXiv2020

Channel-state duality and the separability problem

Separability of quantum states is analyzed with the use of the Choi-Jamiolkowski isomorphism. Spectral separability criteria are derived. The presented approach is illustrated with various examples, among which a separable decomposition of 2 \otimes 2 isotropic states is obtained.

quant-ph↗
arXiv2020

Lower bounds on concurrence and negativity from a trace inequality

For bipartite quantum states we obtain lower bounds on two important entanglement measures, concurrence and negativity, studying the inequalities for the expectation value of a projector on some subspace of the Hilbert space. Several applications, including analysis of stability of entanglement under various perturbations of a state, are discussed.

quant-ph↗
arXiv2020

Bosonic bright soliton in the mixture of repulsive Bose-Einstein condensate and polarized ultracold fermions under influence of the pressure evolution

Repulsive Bose-Einstein condensate, where the short-range interaction is included up to the third order by the interaction radius, demonstrates existence of a bright soliton in a narrow interval of parameters. This soliton is studied here for the boson-fermion mixture, where spin-1/2 fermions are consider in the regime of full spin polarization. Influence of fermions via the boson-fermion interaction is considered up to the third order by the interaction radius. Fermions themselves are considered by hydrodynamic model including the pressure evolution equation. Interaction between fermions is considered. The first order by the interaction radius gives zero contribution in the Euler equation and the pressure evolution equation, but the third order by the interaction radius provides nonzero contributions in both equations. Repulsive (attractive) boson-fermion interaction leads to the bright (dark) fermionic soliton.

cond-mat.quant-gas↗
arXiv2016

Properties of collapse dynamics in relativistic theory of gravitation in the case of smooth initial matter distributions

We use both numerical and analytical approaches to study the dynamics of the gravitational collapse in the framework of the relativistic theory of gravitation (RTG). We use various equations of state for the collapsing matter and relatively realistic initial conditions with smooth matter distribution, which corresponds to static solution for the given equation of state. We also obtain results concerning the influence of the graviton mass on the properties of static solutions. We specify several characteristics of the process of the collapse, in particular, we determine the dependence of the turning point time (when contraction is replaced by inflation) on the graviton mass. We also study the influence of non-zero pressure on the dynamics of the collapse.

gr-qc↗
arXiv2012

Haag's Theorem in Noncommutative Quantum Field Theory

Haag's theorem was extended to noncommutative quantum field theory in a general case when time does not commute with spatial variables. It was proven that if S-matrix is equal to unity in one of two theories related by unitary transformation, then the corresponding one in another theory is equal to unity as well. In fact this result is valid in any SO(1,1) invariant quantum field theory, of which an important example is noncommutative quantum field theory.

math-ph↗
arXiv2011

Haag's theorem in S O (1, k) invariant quantum field theory

Generalized Haag's theorem has been proved in S O (1, k) invariant quantum field theory. Apart from the above mentioned k+1 variables there can be arbitrary number of additional coordinates including noncommutative ones in the theory. New consequences of generalized Haag's theorem are obtained. It has been proved that the equality of four-point Wightman functions in two theories leads to the equality of elastic scattering amplitudes and thus the total cross-sections in these theories. In space-space noncommutative quantum field theory in four-dimensional case it has been proved that if in one of the theories under consideration S-matrix is equal to unity, then in another theory S-matrix is unity as well.

math-ph↗