Nuclear Theory·nucl-th

Friday·October 18, 2019

10 papers—7 primary·3 cross-listed

08
Projected Cooling Algorithm for Quantum Computation
Dean Lee🇺🇸 · Joey Bonitati🇺🇸 · Gabriel Given🇺🇸 · Caleb Hicks🇺🇸 · Ning Li🇺🇸 · Bing-Nan Lu🇺🇸 · Abudit Rai🇺🇸 · Avik Sarkar🇺🇸 · Jacob Watkins🇺🇸
In the current era of noisy quantum devices, there is a need for quantum algorithms that are efficient and robust against noise. Towards this end, we introduce the projected cooling algorithm for quantum computation. The projected cooling algorithm is able to construct the localized ground state of any Hamiltonian with a translationally-invariant kinetic energy and interactions that vanish at large distances. The term "localized" refers to localization in position space. The method can be viewed as the quantum analog of evaporative cooling. We start with an initial state with support over a compact region of a large volume. We then drive the excited quantum states to disperse and measure the remaining portion of the wave function left behind. For the nontrivial examples we consider here, the improvement over other methods is substantial. The only additional resource required is performing the operations in a volume significantly larger than the size of the localized state. These characteristics make the projected cooling algorithm a promising tool for calculations of self-bound systems such as atomic nuclei.
↳ quant-phcond-mat.quant-gashep-latnucl-thPLB(2020)·26 citations
09
Two-colour QCD phases and the topology at low temperature and high density
Kei Iida🇯🇵 · Etsuko Itou🇯🇵 · Tong-Gyu Lee🇯🇵
We delineate equilibrium phase structure and topological charge distribution of dense two-colour QCD at low temperature by using a lattice simulation with two-flavour Wilson fermions that has a chemical potential $μ$ and a diquark source $j$ incorporated. We systematically measure the diquark condensate, the Polyakov loop, the quark number density and the chiral condensate with improved accuracy and $j \to 0$ extrapolation over earlier publications; the known qualitative features of the low temperature phase diagram, which is composed of the hadronic, Bose-Einstein condensed (BEC) and BCS phases, are reproduced. In addition, we newly find that around the boundary between the hadronic and BEC phases, nonzero quark number density occurs even in the hadronic phase in contrast to the prediction of the chiral perturbation theory (ChPT), while the diquark condensate approaches zero in a manner that is consistent with the ChPT prediction. At the highest $μ$ , which is of order the inverse of the lattice spacing, all the above observables change drastically, which implies a lattice artifact. Finally, at temperature of order $0.45 T_{c}$ , where $T_{c}$ is the chiral transition temperature at zero chemical potential, the topological susceptibility is calculated from a gradient-flow method and found to be almost constant for all the values of $μ$ ranging from the hadronic to BCS phase. This is a contrast to the case of $0.89 T_{c}$ in which the topological susceptibility becomes small as the hadronic phase changes into the quark-gluon plasma phase.
↳ hep-lathep-phnucl-thJHEP(2020)·58 citations
10
Centrality selection effect on higher-order cumulants of net-proton multiplicity distributions in relativistic heavy-ion collisions
Arghya Chatterjee🇨🇳 · Yu Zhang🇨🇳 · Jingdong Zeng🇨🇳 · Nihar Ranjan Sahoo🇨🇳 · Xiaofeng Luo🇨🇳
We studied the centrality selection effect on cumulants (up to fourth order) and the cumulants ratios of net-proton multiplicity distributions in Au+Au collisions at $s_{NN}$ = 7.7, 19.6 and 200 GeV from UrQMD model. The net-proton cumulants are calculated with collision centralities by using charged particle multiplicity from different pesudorapidity ( $η$ ) region. By comparing the results from various collision centralities, we found that the autocorrelation effects are not significant in the results with collision centralities "refmult-3" and "refmult-2", which are using mid-rapidity charged particles but excluding (anti-)protons and analysis region, respectively. Furthermore, due to the contributions of spectator protons, we observed poor centrality resolution when using charged particles at forward $η$ region at low energies. This work can serve as a baseline for centrality selection of future fluctuations analysis in relativistic heavy-ion collisions.
↳ nucl-exhep-phnucl-thPRC(2020)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE

Projected Cooling Algorithm for Quantum Computation

Two-colour QCD phases and the topology at low temperature and high density

Centrality selection effect on higher-order cumulants of net-proton multiplicity distributions in relativistic heavy-ion collisions

Affiliations