The Interacting Photons group investigates physics and applications of interacting photons in optical resonators. We use optical systems to open and explore new frontiers of physics, including:
1. Scaling, Universality, and non-Markovian dynamics in phase transition of light
Driven nonlinear dynamical systems can reside in two steady states at a single driving condition. This feature, known as bistability, is associated with emergent phenomena in phase transitions, scaling, and universal behavior. In the Interacting Photons group, we use bistable optical cavities to explore the physics of scaling, universality, and non-Markovian dynamics. In Ref.  we discovered a universal scaling law for the dynamic hysteresis of a Kerr nonlinear cavity influenced by quantum fluctuations. More recently, in Ref.  we discovered a universal scaling law for the hysteresis area of a cavity with memory in its nonlinear response. The interplay of noise and memory in this system leads to a new class of non-Markovian dynamics which we recently realized.
References S. R. K. Rodriguez et al., Phys. Rev. Lett. 118, 247402 (2017). pdf  Z. Geng et al., Phys. Rev. Lett. 124, 153063 (2020). pdf
2. Classical and quantum emergent phenomena in driven-dissipative systems
Optical systems exhibit fascinating emergent phenomena due to the interplay of driving, dissipation, nonlinearity. For instance, we have recently realized the first superfluid of light at room temperature and in steady state . In this state, light can flow into an obstacle without scattering, like a superfluid. In another line of ERC-funded research, we are investigating how an optical cavity can modify the electrical conductivity of a material, possibly enabling the observation of high-temperature superconductivity induced by light.
References G. Keijsers et al., arXiv:2012.13463
3. Noise as a resource in optics
Noise plays a constructive role in many natural and artificial systems. For example, noise enables paddlefish to detect their prey. In the Interacting Photons group, we investigate what new physics and functionalities can be derived from optical noise (fluctuations in light amplitude or phase). For example, we have recently reported the first observation of non-Markovian stochastic resonance . In stochastic resonance, a finite amount of noise can serve to amplify a periodic signal and thereby ease its detection. Suprisingly, thanks to memory effects (responsible for non-Markovian dynamics), this amplification can occur across an extremely large bandwidth /
References K. Peters et al., arXiv:2008.11615
4. Photonic devices
Besides pursuing a deeper understanding of fundamental physics, we investigate various applications of our research. These applications are in the fields of sensing, computation, energy harvesting, and optical isolation. For example, in Ref.  we showed how the detection speed and sensitivity of a nonlinear optical sensor can be enhanced with noise. In Ref.  we showed how to realize a nonlinear optical isolator with zero reflection.
References S.R.K. Rodriguez
Enhancing the speed and sensitivity of a nonlinear optical sensor with noise
Phys. Rev. Applied 13, 024032 (2020). pdf  S.R.K. Rodriguez, V. Goblot, N. Carlon Zambon, A. Amo, and J. Bloch
Non-reciprocity and zero reflection in nonlinear cavities with tailored loss
Phys. Rev. A 99, 013851 (2019). pdf