# Designing quantum systems through correlations and backaction

Supervisor: Dr Bernd Braunecker (St Andrews)

Quantum simulation offers the possibility to create physical phenomena that are hard to access or control otherwise. In particular notorious is many-body physics with strong correlations. But remarkably some types of such physics can be created in dissipative quantum circuits in which the type of correlation physics appears through a nonlinear interaction of the electron transport with electromagnetic environment fluctuations. For weakly transmitting conductors such physics is understood since a long time [1]. Yet the potential of the quantum simulation appears only for highly transmitting circuits in which the transmission time is comparable with the environment's reaction time, called the dynamical Coulomb blockade regime, for which much less is known. Although for specific conditions important advances have been made over the last years [2], recent experimental progress has shown that much remains unclear, especially when there is strong backaction of the environment [3]. In this PhD project we will access this physics through analytical and numerical non-perturbative many-body modelling, including bosonisation [4] and recently developed mappings on scattering boundary value problems [5]. [1] G.-L. Ingold and Y. Nazarov, in "Single Charge Tunneling", ed. by H. Grabert and M. H. Devoret, Ch. 2 (Plenum, 1992). [2] K. A. Matveev, D. Yue and L. I. Glazman, Phys. Rev. Lett. 71, 3351 (1993); L. W. K. Molenkamp, K. Flensberg and M. Kemerink, Phys. Rev. Lett. 75, 4282 (1995). Y. V. Nazarov, Phys. Rev. Lett. 82, 1245 (1999); M. Kindermann and Y. V. Nazarov, Phys. Rev. Lett. 91, 136802 (2003); I. Safi and H. Saleur, Phys. Rev. Lett. 93, 126602 (2004); D. S. Golubev, A. V. Galaktionov and A. D. Zaikin, Phys. Rev. B 72, 205417 (2005). [3] F. D. Parmentier et al, Nat. Phys. 7, 935 (2011); A. Anthore et al, Phys. Rev. X 8, 031075 (2018). [4] J.-R. Souquet, I. Safi, and P. Simon, Phys. Rev. B 88, 205419 (2013). [5] B. A. Muzykantskii and Y. Adamov, Phys. Rev. B 68, 155304 (2003); B. Muzykantskii, N. d'Ambrumenil, and B. Braunecker, Phys. Rev. Lett. 91, 266602 (2003); J. Zhang, Y. Sherkunov, N. d'Ambrumenil, and B. Muzykantskii, Phys. Rev. B 80, 245308 (2009); B. Braunecker, Phys. Rev. B. 73, 075122 (2006).