Here, we present a solution to this issue by realizing low-loss (0. 81 dB), broadband (at least 50 GHz bandwidth) and high-extinction (up to 27 dB) circulators, based on Mach-Zehnder interferometers including so-called fiber null-couplers. An Optical Circulator is a non-reciprocal device that routes light from one. Here, we show the use of the chiral cross-Kerr nonlinearity of atoms at room temperature to realize optical isolation, circumventing dynamical reciprocity. Their low insertion loss makes them ideal tools for the transmission and processing of optically encoded quantum information.