YQI Talk - Michael Horodynski - MIT

 

Understanding and controlling multimode nonlinear photonic systems is crucial for applications like high-power fiber lasers, optical communications, mode-locked lasers, wavefront shapers, and physical neural networks. So far, the focus has been on controlling the average (so-called “mean-field”) properties of light: those described by the classical Maxwell equations.  At the same time, the statistical properties of light are of both fundamental interest and potential practical importance for the applications above. Specifically, quantum noise sets fundamental limits on applications (e.g., imaging, communications, and interferometry). Overcoming such limits requires generating quantum states of light, such as squeezed or entangled states, as enabled by second- and third-order nonlinear media.

 

In this work, we show theoretically that in multimode nonlinear systems (natural experimental platforms include nonlinear waveguide arrays and multimode fibers), the noise distribution across output modes depends strongly on initial conditions, i.e., the input light’s phase and amplitude. We predict that controlling the initial conditions allows for creating squeezed states of light at high powers, even when we use a noisy laser in various photonic platforms. 

 

Motivated by this, we performed a proof-of-principle experiment that demonstrated the feasibility of our approach. We shape the wavefront of a pulsed laser with a spatial light modulator and couple this beam into a multi-mode fiber. At the output facet of the fiber, we then measure the spatial distribution of intensity and intensity noise. We show that by finding the right phase pattern at the spatial light modulator we can minimize the intensity noise at a specific point of the beam while keeping the average intensity fixed.