 In order to deal with these challenges, several ingenious solutions have been devised, including quantum error correction codes and fault tolerant computation (Shor 1995; Shor and DiVincenzo 1996; Aharonov and Ben-Or 1997; Raussendorf, Harrington, and Goyal 2008; Horsman et al. 2012; De Beaudrap and Horsman 2019) which can dramatically reduce the spread of errors during a ‘noisy’ quantum computation. An important criticism of these active error correction schemes, however, is that they are devised for a very unrealistic noise model which treats the computer as quantum and the environment as classical (Alicki, Lidar, and Zinardi 2006). Once a more realistic noise model is allowed, the feasibility of large scale, fault tolerant and computationally superior quantum computers is less clear (Hagar 2009; Tabakin 2017).