OK with Sec IIIA

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Pierre-Francois Loos 2022-09-15 15:19:41 +02:00
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@ -418,43 +418,42 @@ We shall not here insist on these practical details that are discussed, for exam
During the simulation, walkers move from state to state with the possibility of being trapped a certain number of times on the same state before
exiting to a different state. This fact can be exploited in order to integrate out some part of the dynamics, thus leading to a reduction of the statistical
fluctuations. This idea was proposed some time ago \cite{Assaraf_1999A,Assaraf_1999B,Caffarel_2000} and applied to the SU(N) one-dimensional Hubbard model.
fluctuations. This idea was proposed some time ago \cite{Assaraf_1999A,Assaraf_1999B,Caffarel_2000} and applied to the SU($N$) one-dimensional Hubbard model.
Let us consider a given state $|i\rangle$. The probability that the walker remains exactly $n$ times on $|i\rangle$ ($n$ from
1 to $\infty$) and then exits to a different state $j$ is
Considering a given state $\ket{i}$, the probability that a walker remains exactly $n$ times in $\ket{i}$ (with $1 \le n < \infty$) and then exits to a different state $j$ (with $j \neq i$) is
\be
\cP_{i \to j}(n) = \qty(p_{i \to i})^{n-1} p_{i \to j} \qq{$j \ne i$.}
\cP_{i \to j}(n) = \qty(p_{i \to i})^{n-1} p_{i \to j}.
\ee
Using the relation
\be
\sum_{n=1}^{\infty} (p_{i \to i})^{n-1}=\frac{1}{1-p_{i \to i}}
\ee
and the normalization of the $p_{i \to j}$, Eq.~\eqref{eq:sumup}, we verify that the probability is normalized to one
and the normalization of the $p_{i \to j}$'s [see Eq.~\eqref{eq:sumup}], one can check that the probability is properly normalized, \ie,
\be
\sum_{j \ne i} \sum_{n=1}^{\infty} \cP_{i \to j}(n) = 1.
\ee
The probability of being trapped during $n$ steps is obtained by summing over all possible exit states
Naturally, the probability of being trapped during $n$ steps is obtained by summing over all possible exit states
\be
P_i(n)=\sum_{j \ne i} \cP_{i \to j}(n) = \qty(p_{i \to i})^{n-1} \qty( 1 - p_{i \to i} ).
P_i(n)=\sum_{j \ne i} \cP_{i \to j}(n) = \qty(p_{i \to i})^{n-1} \qty( 1 - p_{i \to i} ),
\ee
This probability defines a Poisson law with an average number $\bar{n}_i$ of trapping events given by
and this defines a Poisson law with an average number of trapping events
\be
\bar{n}_i= \sum_{n=1}^{\infty} n P_i(n) = \frac{1}{1 -p_{i \to i}}.
\ee
Introducing the continuous time $t_i=n_i\tau$ the average trapping time is given by
Introducing the continuous time $t_i = n \tau$, the average trapping time is thus given by
\be
\bar{t_i}= \frac{1}{H^+_{ii}-(\EL^+)_{i}}.
\ee
Taking the limit $\tau \to 0$, the Poisson probability takes the usual form
In the limit $\tau \to 0$, the Poisson probability takes the usual form
\be
P_{i}(t) = \frac{1}{\bar{t}_i} \exp(-\frac{t}{\bar{t}_i})
P_{i}(t) = \frac{1}{\bar{t}_i} \exp(-\frac{t}{\bar{t}_i}).
\ee
The time-averaged contribution of the \titou{on-state} weight can be easily calculated to be
The time-averaged contribution of the on-state weight can be easily calculated to be
\be
\bar{w}_i= \sum_{n=1}^{\infty} w^n_{ii} P_i(n)= \frac{T_{ii}}{T^+_{ii}} \frac{1-T^+_{ii}}{1-T_{ii}}
\ee
Details of the implementation of the effective dynamics can be in found in Refs.~\onlinecite{Assaraf_1999B} and \onlinecite{Caffarel_2000}.
Details of the implementation of this effective dynamics can be in found in Refs.~\onlinecite{Assaraf_1999B} and \onlinecite{Caffarel_2000}.
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\subsection{General domains}