We show that the contact process on a random $d$-regular graph initiated by a single infected vertex obeys the “cutoff phenomenon” in its supercritical phase. In particular, we prove that, when the infection rate is larger than the lower critical value of the contact process on the infinite $d$-regular tree, there are positive constants $C$, $p$ depending on the infection rate such that for any $\varepsilon>0$, when the number $n$ of vertices is large then (a) at times $t<(C-\varepsilon)\log n$ the fraction of infected vertices is vanishingly small, but (b) at time $(C+\varepsilon)\log n$ the fraction of infected vertices is within $\varepsilon$ of $p$, with probability $p$.
References
[1] Bhamidi, S., van der Hofstad, R. and Hooghiemstra, G. Universality for first passage percolation on sparse random graphs. Available at arXiv:1210.6839. 1210.6839 MR3693970 10.1214/16-AOP1120 euclid.aop/1502438435
[1] Bhamidi, S., van der Hofstad, R. and Hooghiemstra, G. Universality for first passage percolation on sparse random graphs. Available at arXiv:1210.6839. 1210.6839 MR3693970 10.1214/16-AOP1120 euclid.aop/1502438435
[4] Bollobás, B. and Fernandez de la Vega, W. (1982). The diameter of random regular graphs. Combinatorica 2 125–134. MR685038 10.1007/BF02579310[4] Bollobás, B. and Fernandez de la Vega, W. (1982). The diameter of random regular graphs. Combinatorica 2 125–134. MR685038 10.1007/BF02579310
[5] Chatterjee, S. and Durrett, R. (2013). A first order phase transition in the threshold $\theta\geq2$ contact process on random $r$-regular graphs and $r$-trees. Stochastic Process. Appl. 123 561–578.[5] Chatterjee, S. and Durrett, R. (2013). A first order phase transition in the threshold $\theta\geq2$ contact process on random $r$-regular graphs and $r$-trees. Stochastic Process. Appl. 123 561–578.
[6] Cranston, M., Mountford, T., Mourrat, J.-C. and Valesin, D. (2014). The contact process on finite homogeneous trees revisited. ALEA Lat. Am. J. Probab. Math. Stat. 11 385–408.[6] Cranston, M., Mountford, T., Mourrat, J.-C. and Valesin, D. (2014). The contact process on finite homogeneous trees revisited. ALEA Lat. Am. J. Probab. Math. Stat. 11 385–408.
[7] Ding, J., Sly, A. and Sun, N. Maximum independent sets on random regular graphs. Available at arXiv:1310.4787. 1310.4787 MR3689942 10.1007/s11511-017-0145-9 euclid.acta/1502989202
[7] Ding, J., Sly, A. and Sun, N. Maximum independent sets on random regular graphs. Available at arXiv:1310.4787. 1310.4787 MR3689942 10.1007/s11511-017-0145-9 euclid.acta/1502989202
[10] Hoory, S., Linial, N. and Wigderson, A. (2006). Expander graphs and their applications. Bull. Amer. Math. Soc. (N.S.) 43 439–561 (electronic). MR2247919 10.1090/S0273-0979-06-01126-8[10] Hoory, S., Linial, N. and Wigderson, A. (2006). Expander graphs and their applications. Bull. Amer. Math. Soc. (N.S.) 43 439–561 (electronic). MR2247919 10.1090/S0273-0979-06-01126-8
[16] Morrow, G., Schinazi, R. and Zhang, Y. (1994). The critical contact process on a homogeneous tree. J. Appl. Probab. 31 250–255. MR1260587 10.2307/3215251[16] Morrow, G., Schinazi, R. and Zhang, Y. (1994). The critical contact process on a homogeneous tree. J. Appl. Probab. 31 250–255. MR1260587 10.2307/3215251
[18] Mourrat, J.-C. and Valesin, D. Phase transition of the contact process on random regular graphs. Available at arXiv:1405.0865. 1405.0865[18] Mourrat, J.-C. and Valesin, D. Phase transition of the contact process on random regular graphs. Available at arXiv:1405.0865. 1405.0865
[20] Stacey, A. (1996). The existence of an intermediate phase for the contact process on trees. Ann. Probab. 24 1711–1726. MR1415226 10.1214/aop/1041903203 euclid.aop/1041903203
[20] Stacey, A. (1996). The existence of an intermediate phase for the contact process on trees. Ann. Probab. 24 1711–1726. MR1415226 10.1214/aop/1041903203 euclid.aop/1041903203
[22] Wormald, N. C. (1999). Models of random regular graphs. In Surveys in Combinatorics, 1999 (Canterbury). London Mathematical Society Lecture Note Series 267 239–298. Cambridge Univ. Press, Cambridge.[22] Wormald, N. C. (1999). Models of random regular graphs. In Surveys in Combinatorics, 1999 (Canterbury). London Mathematical Society Lecture Note Series 267 239–298. Cambridge Univ. Press, Cambridge.