I came across a handbook named "Lecture Notes on Cryptography" from Shafi Goldwasser and Mihir Bellare and I read their definition 3.1 about poly-time indistinguishability:
Let $X_n,Y_n$ be probability distributions on $\{0,1\}^n$ (That is, by $t\in X_n$ we mean that $t\in\{0,1\}^n$ and it is selected according to the distribution $X_n$).
We say that $\{X_n\}$ is poly-time indistinguishable from $\{Y_n\}$ if $\forall \text{PTM } A, \forall \text{polynomial } Q, \exists n_0, \text{s.t. } \forall n>n_0$,
$$\left|\Pr_{t\in X_n}(A(t)=1)-\Pr_{t\in Y_n}(A(t)=1)\right|<\frac1{Q(n)}$$
What I don't understand is what "PTM" means, can you please explain it to me?