arXiv subjects

P. Deb

Publications and source records attributed to P. Deb.

3 recordsLinked to original sources

arXiv2022

Study of net-baryon higher moments in PNJL model and their expectation for net-proton using the Subensemble Acceptance Method for the search of QCD critical point

One of the most important parts of the QCD phase diagram of strongly interacting matter is the Critical End Point. The non-monotonic behavior of the conserved quantities like net-baryon ($\Delta B$), net-charge ($\Delta Q$), and net-strangeness ($\Delta S$) are believed to be the signatures of the QCD Critical End Point (CEP) as a function of the energy. We study the effect of the QCD critical point on moments of net-baryon in the Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model of QCD with six quark and eight quark interactions. The study is performed at energies similar to RHIC beam energy scan (BES). Experimentally measuring conserved quantities is difficult due to systematic limitations, therefore net-proton, net-pion, and net-kaon are measured as the proxy of $\Delta B$, $\Delta Q$, and $\Delta S$. Thus the need for different models becomes predominant to estimate the value of different observables. Higher-order moments like skewness ($S$), kurtosis ($\kappa$), and their system volume independent products ($ M/\sigma^{2}, s\sigma$, $\kappa\sigma^{2}$) which are calculated in the PNJL model, are sensitive to the produced correlation length of the hot and dense medium, making them more prone to search for the critical point. Recent studies in the subensemble acceptance method (SAM) on the HRG model shows the dependency of the measure higher order moment on the experimental acceptance. We used SAM to analyze the behavior of $\kappa\sigma^{2}$ of net baryon distribution within the subvolume system for various acceptance fractions. These results can be directly mapped to the percentage of the subvolume (particle) of the total volume (conserved quantities). The results are compared to the STAR net-proton and proton data with different energies to understand the existence of critical point. For reference, results are also compared with the theoretical UrQMD and HRG models.

hep-ph↗

arXiv2022

Enhancing Spin Coherence in Optically Addressable Molecular Qubits through Host-Matrix Control

Optically addressable spins are a promising platform for quantum information science due to their combination of a long-lived qubit with a spin-optical interface for external qubit control and read out. The ability to chemically synthesize such systems - to generate optically addressable molecular spins - offers a modular qubit architecture which can be transported across different environments, and atomistically tailored for targeted applications through bottom-up design and synthesis. Here we demonstrate how the spin coherence in such optically addressable molecular qubits can be controlled through engineering their host environment. By inserting chromium (IV)-based molecular qubits into a non-isostructural host matrix, we generate noise-insensitive clock transitions, through a transverse zero-field splitting, that are not present when using an isostructural host. This host-matrix engineering leads to spin-coherence times of more than 10 microseconds for optically addressable molecular spin qubits in a nuclear and electron-spin rich environment. We model the dependence of spin coherence on transverse zero-field splitting from first principles and experimentally verify the theoretical predictions with four distinct molecular systems. Finally, we explore how to further enhance optical-spin interfaces in molecular qubits by investigating the key parameters of optical linewidth and spin-lattice relaxation time. Our results demonstrate the ability to test qubit structure-function relationships through a tunable molecular platform and highlight opportunities for using molecular qubits for nanoscale quantum sensing in noisy environments.

quant-ph↗

arXiv2022

Study of finite volume number density fluctuations in the SU(3) Polyakov loop extended Nambu-Jona-Lasinio model for the search of the QCD Critical Point

The critical endpoint (CEP) is a fundamental feature of the Quantum Chromodynamics (QCD) phase diagram, marking the boundary between quark-gluon plasma and hadronic matter. Heavy-ion collision experiments, such as the RHIC Beam Energy Scan, aim to probe the QCD phase diagram by varying collision energy. However, the short-lived nature of produced particles makes direct measurements challenging, necessitating theoretical models. This study explores the impact of density fluctuations on the CEP using the Polyakov-loop enhanced Nambu-Jona-Lasinio (PNJL) model, focusing on quark number densities in both finite and infinite volume systems. Quark number densities, derived from thermodynamic susceptibilities, serve as reliable predictors for the CEP's location. We calculate density fluctuations and normalize them by $T^3$ as functions of temperature and $T/\mu_x$ (where x represents light quarks, strange quarks, and baryons), analyzing inflection points and maxima to estimate the critical region. To compare the experimental data, the study has been performed at energies identical to those of the RHIC Beam Energy Scan. The results highlight the influence of finite volume effects on quark density fluctuations, and key indicators of QCD phase transitions, and provide quantitative comparisons with experimental data. This work enhances our understanding of QCD phase structure and supports the ongoing search for the CEP in high-energy heavy-ion collisions, bridging theoretical predictions and experimental observations.

hep-ph↗