publications

2024

1. Quantum

   From Non-Markovian Dissipation to Spatiotemporal Control of Quantum Nanodevices

   Thibaut Lacroix, Brendon W. Lovett, and Alex W. Chin

   Quantum, Apr 2024

   Abs DOI

   Thibaut Lacroix, Brendon W. Lovett, and Alex W. Chin, Quantum 8, 1305 (2024). Nanodevices exploiting quantum effects are critically important elements of future quantum technologies (QT), but their real-world performance is strongly limited by decoherence arising from…

2. J. Chem. Phys.

   MPSDynamics.jl: Tensor network simulations for finite-temperature (non-Markovian) open quantum system dynamics

   Thibaut Lacroix, Brieuc Le Dé, Angela Riva, and 2 more authors

   The Journal of Chemical Physics, Aug 2024

   Abs DOI Code

   The MPSDynamics.jl package provides an easy-to-use interface for performing open quantum systems simulations at zero and finite temperatures. The package has been developed with the aim of studying non-Markovian open system dynamics using the state-of-the-art numerically exact Thermalized-Time Evolving Density operator with Orthonormal Polynomials Algorithm based on environment chain mapping. The simulations rely on a tensor network representation of the quantum states as matrix product states (MPS) and tree tensor network states. Written in the Julia programming language, MPSDynamics.jl is a versatile open-source package providing a choice of several variants of the Time-Dependent Variational Principle method for time evolution (including novel bond-adaptive one-site algorithms). The package also provides strong support for the measurement of single and multi-site observables, as well as the storing and logging of data, which makes it a useful tool for the study of many-body physics. It currently handles long-range interactions, time-dependent Hamiltonians, multiple environments, bosonic and fermionic environments, and joint system–environment observables.

3. arXiv

   Connectivity matters: Impact of bath modes ordering and geometry in Open Quantum System simulation with Matrix Product States

   Thibaut Lacroix, Brendon W. Lovett, and Alex W. Chin

   Sep 2024

   arXiv:2409.04145 [cond-mat, physics:physics, physics:quant-ph]

   Abs DOI

   Being able to study the dynamics of quantum systems interacting with several environments is important in many settings ranging from quantum chemistry to quantum thermodynamics, through out-of-equilibrium systems. For such problems tensor network-based methods are state-of-the-art approaches to perform numerically exact simulations. However, to be used efficiently in this multi-environment non-perturbative context, these methods require a clever choice of the topology of the wave-function Ans}"atze. This is often done by analysing cross-correlations between different system and environment degrees of freedom. We show for canonical model Hamiltonians that simple orderings of bosonic environmental modes, which enable to write the joint {System + Environments} state as a matrix product state, reduce considerably the bond dimension required for convergence. These results suggest that complex correlation analyses in order to tweak tensor networks topology (e.g. entanglement renormalization) are usually not necessary and that tree tensor network states are sub-optimal compared to simple matrix product states in several applications.

2023

1. BUP

   Du quantique au classique : Un modèle simple de décohérence

   Thibaut Lacroix

   Bulletin de l’Union des Physiciens, Oct 2023

   Abs

   Les objets macroscopiques (dont nous faisons partie) obéissent aux lois de la physique classique et sont pourtant composés de constituants obéissant aux lois de la physique quantique. Comment les propriétés quantiques présentes à l’échelle microscopique disparaissent-elles lors du passage à l’échelle macroscopique ? Dans cet article, nous présentons un modèle simple illustrant comment le couplage d’un système quantique à un environnement possédant un grand nombre de degrés de liberté engendre la perte de cohérence quantique du système.

2021

1. Phys. Rev. A

   Unveiling non-Markovian spacetime signaling in open quantum systems with long-range tensor network dynamics

   Thibaut Lacroix, Angus Dunnett, Dominic Gribben, and 2 more authors

   Physical Review A, Nov 2021

   DOI