Nuclear Theory·nucl-th

Wednesday·September 20, 2023

8 papers—4 primary·4 cross-listed

01
Quantum benefit of the quantum equation of motion for the strongly coupled many-body problem
Manqoba Q. Hlatshwayo🇺🇸 · John Novak🇺🇸 · Elena Litvinova🇺🇸
We investigate the quantum equation of motion (qEOM), a hybrid quantum-classical algorithm for computing excitation properties of a fermionic many-body system, with a particular emphasis on the strong-coupling regime. The method is designed as a stepping stone towards building more accurate solutions for strongly coupled fermionic systems, such as medium-heavy nuclei, using quantum algorithms to surpass the current barrier in classical computation. Approximations of increasing accuracy to the exact solution of the Lipkin-Meshkov-Glick Hamiltonian with $N = 8$ particles are studied on digital simulators and IBM quantum devices. Improved accuracy is achieved by applying operators of growing complexity to generate excitations above the correlated ground state, which is determined by the variational quantum eigensolver (VQE). We demonstrate explicitly that the qEOM exhibits a quantum benefit due to the independence of the number of required quantum measurements from the configuration complexity. Post-processing examination shows that quantum device errors are amplified by increasing configuration complexity and coupling strength. A detailed error analysis is presented, and error mitigation based on zero noise extrapolation is implemented.
nucl-thcond-mat.otherquant-phPRC(2024)·14 citations
02
Quark phases in neutron stars consistent with implications of NICER
Y. Yamamoto🇯🇵 · N. Yasutake🇯🇵 · Th.A. Rijken🇯🇵
The analyses for the NICER data imply $R_{2.0 M_{⊙}} = 12.4 1_{- 1.10}^{+ 1.00}$ km and $R_{1.4 M_{⊙}} = 12.5 6_{- 1.07}^{+ 1.00}$ km, indicating the lack of significant variation of the radii from $1.4 M_{⊙}$ to $2.0 M_{⊙}$ . This feature cannot be reproduced by the hadronic matter due to the softening of equation of state (EoS) by hyperon mixing, indicating the possible existence of quark phases in neutron-star interiors. % Two models are used for quark phases: In the quark-hadron transition (QHT) model, quark deconfinement phase transitions from a hadronic-matter EoS are taken into account so as to give reasonable mass-radius ( $M R$ ) curves by adjusting the quark-quark repulsions and the density dependence of effective quark mass. % In the quarkyonic model, the degrees of freedom inside the Fermi sea are treated as quarks and neutrons exist at the surface of the Fermi sea, where $M R$ curves are controlled mainly by the thickness of neutron Fermi layer. % The QHT and quarkyonic EoSs can be adjusted so as to reproduce radii, tidal deformabilities, pressure and central densities inferred from the NICER analysis better than the nucleonic matter EoS, demonstrating the clear impacts of quark phases. Then, the maximum mass for the quakyonic-matter EoS is considerably larger than that for the QHT-matter EoS.
nucl-thastro-ph.HEhep-phPRC(2023)·16 citations
03
Visualizing quantum coherence and decoherence in nuclear reactions
K. Hagino · T. Yoda
Differential cross sections of nuclear reactions often exhibit characteristic oscillations in the angular distribution originated from an interference of two indistinguishable processes. Here we propose a novel method to visualize origins of such oscillations. This is achieved by taking Fourier transform of scattering amplitudes, following the idea in wave optics. We apply this method to elastic scattering of $^{16}$ O+ $^{16}$ O and $^{18}$ O+ $^{18}$ O at energies above the Coulomb barrier. The former system shows strong oscillations in the angular distribution due to the nearside-farside interferences, while the oscillations are largely suppressed in the latter system due to a stronger absorption. We show that the image of the former and the latter systems corresponds to a double-slit and a single-slit problems in quantum mechanics, respectively.
nucl-thhep-phhep-thnucl-exPLB(2024)·5 citations
04
Nuclear descent from the fission barrier in the presence of long--range memory effects
S.V.Radionov
We have investigated the peculiarities of nuclear descent from a parabolic fission barrier within a generalized Langevin equation with power--law $f (t - t^{'}) = (∣ t - t^{'} ∣/ τ)^{- α}$ memory function. We have observed much stronger slowing down of the nuclear descent in the presence of long--range memory effects, caused by the power--law memory function at $0 < α < 1$ , than in the presence of short--range memory effects, generated by exponential $f (t - t^{'}) = exp (- ∣ t - t^{'} ∣/ τ)$ memory function. At a specific value of the exponent $α = 1/2$ of the power--law memory function, it turned out possible to find analytically the trajectory of the descent and demonstrate that the long--range memory effects give rise to complex time oscillations of nuclear shape, becoming more frequent and damped with the correlation time $τ$ . We have found fairly long ( $> 1 0^{- 20} s$ ) times of the descent of $^{236} U$ at the values of the correlation time $τ \sim [1 0^{- 24} \div 1 0^{- 23}] s$ .
nucl-thPRC(2024)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum benefit of the quantum equation of motion for the strongly coupled many-body problem

Quark phases in neutron stars consistent with implications of NICER

Visualizing quantum coherence and decoherence in nuclear reactions

Nuclear descent from the fission barrier in the presence of long--range memory effects

Affiliations