Researchers at the University of Central Florida’s College of Optics and Photonics (CREOL) have made progress in understanding quantum light, focusing on how to manage loss in quantum states to create more robust systems. The Quantum Silicon Photonics (QSP) research group, led by Andrea Blanco-Redondo, is working to uncover fundamental properties of light that could impact future technologies such as quantum computing.
“Understanding these things better is going to lead to real advances in quantum computing, quantum sensing and quantum information science in general,” said Blanco-Redondo.
Quantum states are known for their fragility when exposed to environmental disturbances, which presents challenges for scaling up quantum systems. “Quantum states are very, very fragile, with respect to any kind of perturbation from the environment, so you need to somehow provide protections for the states,” said Amin Hashemi Shahraki ’24MS, a doctoral student and study co-author.
The group’s recent publication in Nature Materials describes a method for precisely controlling dissipation—or loss—of quantum states of light. This control enables robust topological properties that may help address issues caused by imperfections during nanofabrication. “The reason this could have a technological impact is because we are always looking for ways to realize devices that are robust to imperfections that we cannot avoid,” Blanco-Redondo said.
Photonic integrated circuits, which use photons instead of electrons and confine light at the nanoscale, play a key role in this research. These circuits enable nonlinear interactions where photons can become entangled—a critical property for many quantum applications. “Say two photons that come from an initial laser strongly interact with matter,” Blanco-Redondo explained. “What happens is they basically disappear and they give rise to two other photons. These two photons are actually quantum correlated. So just by that nonlinear process, we can create photons that have what’s called entanglement, which is a very fundamental property of quantum particles.”
Blanco-Redondo noted potential improvements in sensing technology as well: “With classical sensors, there’s basically a noise level that you can never surpass,” she said. “When you start using certain quantum properties of light, like superposition, entanglement or squeezing, there are ways to surpass that classical limit and make sensors that are better than anything classical out there.”
Their study explores how topology—referring here to band structures influencing photon propagation—can arise solely from controlled optical loss within photonic systems. “All these studies were basically dealing with systems, where they had this topology, and then you add loss, and then you see what happens,” Blanco-Redondo said. “What we have done is to observe that topology can appear just because of the presence of loss.”
To achieve this control over loss, the team used a photonic version of a field-programmable gate array (FPGA). “But now what we have realized is that you can use it to control the loss very precisely, which has allowed us to demonstrate the appearance of topology solely from loss modulation,” Blanco-Redondo said.
Modulating loss led them to observe localized modes of light resistant to certain types of disorder—a step toward reducing error rates in future quantum computers. “If you can build electromagnetic modes or ways to guide light in a way that is robust to these kinds of imperfections, that could have a tremendous impact,” Blanco-Redondo added.
Another possible application includes topological lasers with improved performance compared to conventional lasers.
Publication in Nature Materials broadens the audience for their work beyond optics specialists. “Being featured in such a prestigious journal, known for its influence across disciplines, is really exciting,” Hashemi Shahraki said.
“It certainly is an exciting time,” Blanco-Redondo agreed. “Especially for people interested in nonlinear optics, quantum optics and integrated photonics. At CREOL you have a community of people with whom you can bounce ideas off. It’s a very collegial, very friendly and very dynamic community.”
While practical applications may take decades as researchers continue exploring robustness methods for quantum states of light within mature fields like integrated photonics and non-Hermitian topological photonics,“We’re taking steps towards a more profound fundamental understanding,” according to Blanco-Redondo.
Blanco-Redondo joined CREOL as Florida Photonics Center of Excellence endowed professor in April 2023 after leading silicon photonics research at Nokia Bell Labs and holding positions at University of Sydney and Tecnalia in Spain. Her work has included discoveries such as pure-quartic solitons and demonstrating topological protection for quantum photonic states.
Hashemi Shahraki holds degrees from Shahrekord University and University of Tabriz; his research focuses on topics including non-Hermitian systems and topological photonics.
