This title appears in the Scientific Report :
2016
Please use the identifier:
http://hdl.handle.net/2128/11963 in citations.
Decoherence and Thermalization at Finite Temperatures for Quantum Systems
Decoherence and Thermalization at Finite Temperatures for Quantum Systems
We consider a quantum system $S$ with Hamiltonian ${\cal H}_S$ coupled via a Hamiltonian ${\cal H}_{SE}$ to a quantum environment $E$ with Hamiltonian ${\cal H}_E$. We assume the entirety $S+E$ is in a canonical-thermal state at an inverse temperature $\beta$. The entirety is a closed quantum sys...
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Personal Name(s): | Novotny, Mark (Corresponding author) |
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Jin, Fengping / Yuan, Shengjun / Miyashita, Seiji / De Raedt, Hans / Michielsen, Kristel | |
Contributing Institute: |
Jülich Supercomputing Center; JSC |
Imprint: |
2016
|
Conference: | 26th IUPAP International conference on Statistical Physics, Lyon (France), 2016-07-18 - 2016-07-22 |
Document Type: |
Poster |
Research Program: |
Computational Science and Mathematical Methods |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
We consider a quantum system $S$ with Hamiltonian ${\cal H}_S$ coupled via a Hamiltonian ${\cal H}_{SE}$ to a quantum environment $E$ with Hamiltonian ${\cal H}_E$. We assume the entirety $S+E$ is in a canonical-thermal state at an inverse temperature $\beta$. The entirety is a closed quantum system which evolves via the time-dependent Schr{\”o}dinger equation with Hamiltonian ${\cal H}={\cal H}_S+{\cal H}_E+\lambda{\cal H}_{SE}$ where $\lambda$ is the overall strength of the system-environment coupling. Using both large-scale simulations and perturbation theory calculations in $\lambda$, we have studied a measure $\sigma(t)$ for decoherence and $\delta(t)$ for thermalization of $S$. We performed large-scale parallel calculations on spin systems with up to $N=40$ spins in the entirety, with both real-time and imaginary-time quantum calculations. We performed perturbation theory calculations about $\lambda=0$ and fluctuations about the average for the canonical-thermal ensemble, for both $\sigma$ and $\delta$. We obtained closed form expressions for both $\sigma$ and $\delta$, in terms of the free energies of $S$ and $E$. Our perturbation theory calculations agree very well with our numerical calculations, at least as long as $\beta\lambda$ is small. |