QTRAJ 1.0: A Lindblad equation solver for heavy-quarkonium dynamics

Bottomonium production in heavy-ion collisions using quantum trajectories: Differential observables and momentum anisotropy

“…3 Details concerning the QTraj implementation, including scaling studies, benchmarks, and runtime comparisons to other methods can be found in Ref. [25]. This reference accompanies the opensource release of QTraj.…”

“…In this work, we compute the QGP survival probability for each physical trajectory and bin the results as is done experimentally. This has been made possible by efficiency and scalability improvements to the QTraj code [25]. As a result of these improvements, we are able to present predictions for R AA and associated double ratios as functions of both N part and p T .…”

Bottomonium suppression and flow in heavy-ion collisions

“…The code used to generate the results presented herein has been released as an open-source package along with detailed documentation in Ref. [8]. Additional theory/data comparisons and discussions can be found in Ref.…”

“…This stems from the fact that one must decompose states in angular momentum and color quantum numbers followed by discretization of the underlying wave-functions on a lattice of size N, resulting in a reduced density matrix with the number of elements proportional to (l max + 1) 2 N 2 , where l max is the largest angular momentum quantum number considered. For reliable computation one must take both a large number of lattice points and a large angular momentum cutoff, which makes directly solving the Lindblad equation numerically prohibitive, with memory size scaling like (l max + 1) 2 N 2 and per step evolution times scaling like (l max + 1) 4 N 4 [8]. 1 When faced with a problem with such high dimensionality it is frequently beneficial to make use of Monte-Carlo methods.…”

“…Additionally, since between quantum jumps the evolution proceeds with fixed color and angular momentum quantum numbers, one does not have to place a cutoff on the magnitude of the angular momentum. Herein, we present results obtained using an open-source code called QTraj, which implements the quantum trajectories algorithm for bottomonium states [8].…”