arXiv subjects

A. Molochkov

Publications and source records attributed to A. Molochkov.

7 recordsLinked to original sources

arXiv2025

Non-Abelian Geometric Phases in Triangular Structures And Universal SU(2) Control in Shape Space

We construct holonomic quantum gates for qubits that are encoded in the near-degenerate vibrational $E$-doublet of a deformable three-body system. Using Kendall's shape theory, we derive the Wilczek--Zee connection governing adiabatic transport within the $E$-manifold. We show that its restricted holonomy group is $\mathrm{SU}(2)$, implying universal single-qubit control by closed loops in shape space. We provide explicit loops implementing a $\pi/2$ phase gate and a Hadamard-type gate. For two-qubit operations, we outline how linked holonomic cycles in arrays generate a controlled Chern--Simons phase, enabling an entangling controlled-$X$ (CNOT) gate. We present a Ramsey/echo interferometric protocol that measures the Wilson loop trace of the Wilczek--Zee connection for a control cycle, providing a gauge-invariant signature of the non-Abelian holonomy. As a physically realizable demonstrator, we propose bond-length modulations of a Cs($6s$)--Cs($6s$)--Cs($nd_{3/2}$) Rydberg trimer in optical tweezers and specify operating conditions that suppress leakage out of the $E$-manifold.

quant-ph↗

arXiv2019

New way of collision experiment data analysis based on Grand Canonical Distribution and Lattice QCD data

We propose new way of heavy ion collisions experiment data analysis. We analyze physical parameters of fireball created in RHIC experiment based on Grand Canonical Distribution and different Lattice QCD data available at the moment. Our results on chemical potential are in agreement with previous model estimations and do not depend on Lattice setup. At same time, we found possible T(V) states of fireball and estimated the most probable temperature and volume of fireball as function of collision energy. We conclude that hadrom matter at RHIC experiment is thermalized and described by Grand Canonical Distribution.

hep-lat↗

arXiv2018

Lattice QCD thermodynamics at finite chemical potential and its comparison with Experiments

We compare higher moments of baryon numbers measured at the RHIC heavy ion collision experiments with those by the lattice QCD calculations. We employ the canonical approach, in which we can access the real chemical potential regions avoiding the sign problem. In the lattice QCD simulations, we study several fits of the number density in the pure imaginary chemical potential, and analyze how these fits affects behaviors at the real chemical potential. In the energy regions between $\sqrt{s}_{NN}$=19.6 and 200 GeV, the susceptibility calculated at $T/T_c=0.93$ is consistent with experimental data at $0 \le μ_B/T < 1.5$, while the kurtosis shows similar behavior with that of the experimental data in the small $μ_B/T$ regions $0 \le μ_B/T < 0.3$. The experimental data at $\sqrt{s}_{NN}=$ 11.5 shows quite different behavior. The lattice result in the deconfinement region,$T/T_c=1.35$, is far from experimental data.

hep-lat↗

arXiv2017

Restoring canonical partition functions from imaginary chemical potential

Using GPGPU techniques and multi-precision calculation we developed the code to study QCD phase transition line in the canonical approach. The canonical approach is a powerful tool to investigate sign problem in Lattice QCD. The central part of the canonical approach is the fugacity expansion of the grand canonical partition functions. Canonical partition functions $Z_n(T)$ are coefficients of this expansion. Using various methods we study properties of $Z_n(T)$. At the last step we perform cubic spline for temperature dependence of $Z_n(T)$ at fixed $n$ and compute baryon number susceptibility $χ_B/T^2$ as function of temperature. After that we compute numerically $\partialχ/ \partial T$ and restore crossover line in QCD phase diagram. We use improved Wilson fermions and Iwasaki gauge action on the $16^3 \times 4$ lattice with $m_π/m_ρ = 0.8$ as a sandbox to check the canonical approach. In this framework we obtain coefficient in parametrization of crossover line $T_c(μ_B^2)=T_c\left(c-κ\, μ_B^2/T_c^2\right)$ with $κ= -0.0453 \pm 0.0099$.

hep-lat↗

arXiv2016

Sign problem in finite density lattice QCD

The canonical approach, which was developed for solving the sign problem, may suffer from a new type of sign problem. In the canonical approach, the grand partition function is written as a fugacity expansion: $Z_G(μ,T) = \sum_n Z_C(n,T) ξ^n$, where $ξ=\exp(μ/T)$ is the fugacity, and $Z_C(n,T)$ are given as averages over a Monte Carlo update, $\langle z_n\rangle$. We show that the complex phase of $z_n$ is proportional to $n$ at each Monte Carlo step. Although $\langle z_n\rangle$ take real positive values, the values of $z_n$ fluctuate rapidly when $n$ is large, especially in the confinement phase, which gives a limit on $n$. We discuss possible remedies for this problem.

hep-lat↗

arXiv2008

Sea-quark flavor asymmetry in the nucleon from a relativistic analysis of the Drell-Yan scattering off nuclei

It is shown that accounting for the relativistic structure of the deuteron allows to explain the ratio of the Drell-Yan pair production cross-section at the low Bjorken $x$ off the deuteron and the proton. Thus, the sea quark distributions in the nucleon should be studied with accounting for the effects of the relativistic structure of the deuteron. The suggested approach reduces theoretical uncertainty in extracting the ratio $\bar u/\bar d$ from the data and it is important for the clarification of the nature of the sea quark asymmetry in the nucleon.

hep-ph↗

arXiv2004

Nucleon Structure Functions and Nuclear DIS

The nucleon structure study in nuclear deep inelastic scattering is considered. It is shown that nuclear data provide a new source of information about dynamics of parton distributions in the nucleon. An example of the neutron structure function extraction from the deuteron and proton data is considered. The limit $x\to 1$ of the neutron to proton structure functions ratio is studied. A link between the deep inelastic scattering off the nucleon at high $x$ and elastic scattering off nuclei in high $Q^2$ region is discussed.

hep-ph↗