Quantum mechanics is fundamental to the description of light, which is often described both as an electromagnetic wave, and a particle (the photon). The particle-nature of light leads to a host of effects that do not exist in the classical world. The description of these effects is a major goal of the field of “quantum optics” which was initiated by confounding correlations intrinsic to starlight (Hanbury Brown and Twiss), as well as by trying to understand the fundamental properties of laser light.

Quantum optics rules over the statistical properties of light, and specifically, enforces fundamental limits on the signal-to-noise ratio in a wide range of measurements that employ light. By taming quantum noise, many important applications can be realized in microscopy, imaging, and other experiments limited by signal-to-noise. A high-profile example is gravitational wave detection, where “squeezed states” of light, with reduced noise, have been used to lower the noise floor of an interferometer designed to detect gravitational waves.  

Controlling noise often requires the use of interactions between photons, which are realized by nonlinear optical materials. A large part of my research is focused on finding new ways to understand and control the noise of light in nonlinear optical devices. For examples, see [1] for a new unified framework we developed to predict quantum noise in complex nonlinear optical devices. In [1], we also applied this framework to describe experiments revealing the fundamental quantum description of important noise-limited nonlinear effects such as supercontinuum generation. There, we showed several new low-noise regimes of supercontinuum which exploit multimode correlations. We have exploited these correlation effects to generate quantum light from high-power noisy inputs, which is a key bottleneck towards realizing quantum light sources in a wide array of settings. Currently, we are working on realizing quantum light generation in highly multimode nonlinear systems such as large-area optical fibers, which will allow generating quantum light at very high powers, as well as generating quantum light with far more complex correlations than previously possible [2]. Our group is currently working broadly on three main directions: (1) realizing quantum states of light in new settings, (2) developing new applications of quantum light, and (3) developing new platforms for nonlinear optics.

We are also excited about the possibility of using nonlinear control of noise to realize other important technologies such as low-noise, or even noiseless amplifiers, see [3]. We are excited about this because amplifiers add fundamental noise to devices, which lead to limits for example, in optical data transmission.

Nonlinear nanophotonic structures enabling deterministic stabilization of “non-Gaussian” states. Certain resonators with nonlinear media in them can make certain quantum states of light in the cavity lossless, causing these states to be deterministically created from a wide range of inputs. Above (and in [4]), we show how a nonlinear photonic crystal cavity pumped into an initially classical “coherent” state can deterministically decay into a large Fock state. Such states have been challenging to generate at optical frequencies, with their deterministic realization remaining a major goal.

Another major part of my research deals with the science and application of “few-photon-scale” optical nonlinearities. Advances in the field of “quantum nonlinear optics” have enabled the development of materials which display nonlinear optical response which can be triggered by just a few photons. This differs drastically from bulk materials, where very strong light intensities are needed to trigger nonlinear effects. Here, rather than effects like “squeezing” and “noise control”, nonlinearities offer a path to generating fundamental quantum states that we learn about in basic quantum classes. Many of these “non-Gaussian” states are important for applications in quantum computation, information processing, communication, and metrology. Here, we are excited by possibilities of designing new novel nonlinear architectures to deterministically generate and stabilize non-Gaussian states, at optical frequencies. See [4,5] for a recent example. 

Last, but not least, we are also interested in fundamental quantum descriptions of a range of important effects, such as free-electron spontaneous emission [6], and high-harmonic generation [7]. 

References

1. Shiekh Zia Uddin*, Nicholas Rivera*, Devin Seyler, Yannick Salamin, Jamison Sloan, Charles Roques-Carmes, Shutao Xu, Michelle Sander, and Marin Soljačić. “Noise-immune squeezing of intense light.” Nature Photonics (2025).

2. Shiekh Zia Uddin, Jamison Sloan, Nicholas Rivera, Sahil Pontula, Yannick Salamin, Michael Birk, Pavel Sidorenko, Ido Kaminer, Marin Soljačić. “Quantum correlations in multimode nonlinear optics.” Conference on Lasers and Electro-Optics (2024).

3. Linh Nguyen, Jamison Sloan, Nicholas Rivera, and Marin Soljačić. “Intense squeezed light from lasers with sharply nonlinear gain at optical frequencies.”  Physical Review Letters (2023).

4. Nicholas Rivera, Jamison Sloan, Yannick Salamin, John D. Joannopoulos, and Marin Soljačić. “Creating large Fock states and massively squeezed states in optics using systems with nonlinear bound states in the continuum.” PNAS (2023).

5. Jamison Sloan*, Nicholas Rivera*, and Marin Soljacic. “Driven-dissipative phases and dynamics in non-Markovian nonlinear photonics.” Optica (2024).

6. Adi Ben-Hayun, Ori Reinhardt, Jonathan Nemirovsky, Aviv Karnieli, Nicholas Rivera, and Ido Kaminer. “Shaping quantum photonic states using free electrons“. Science Advances (2021).

7. Alexey Gorlach, Ofer Neufeld, Nicholas Rivera, Oren Cohen, and Ido Kaminer. “On the quantum optical nature of high-harmonic generation.” Nature Communications (2020).