QUANTUM OPTICAL MEMRISTOR

Quantum optical memristor (1) for manipulating photon quantum states comprising:- a Mach-Zehnder interferometer (2) having at least a first optical input (3) and having a first optical output (5) and a second optical output (6), wherein the first optical input (3) and the first optical output (5) of the Mach-Zehnder interferometer (2) are a first optical input (7) and a first optical output (8) of the quantum optical memristor (1) respectively; and- a detector (9) configured to detect a time-dependent optical signal n(t) at the second optical output (6) of the Mach-Zehnder interferometer (2); and- a controller (10) configured to compute a target reflectivity Rtarget of the Mach-Zehnder interferometer (2), wherein the controller (10) is configured to update the reflectivity R(t) of the Mach-Zehnder interferometer (2) to match the computed target reflectivity Rtarget,wherein the controller (10) is configured to compute the target reflectivity Rtarget based on the derivative of the reflectivity Ṙ(t) with respect to time, wherein the derivative of the reflectivity Ṙ(t) with respect to time is a linear function of the detected signal n(t).