Researchers for the Institute for Quantum Computing (IQC) at the University of Waterloo have demonstrated the experimental feasibility of subtracting photons from light pulses using a solid-state quantum emitter and a chiral optical waveguide, a unique structure where a photon’s spin dictates its travel direction. This on-chip module, detailed in a new paper, requires only a single laser as input and could potentially improve the efficiency of quantum technologies like communications and sensing by integrating into existing systems.
Michal Bajcsy, IQC faculty and Professor, Department of Electrical and Computer Engineering, explains, “and this new paper shows how we can do this.” The work builds on the doctoral research of Abdolreza Pasharavesh at IQC, proposing a practical method for generating quantum states from simple laser pulses.
The foundation for on-chip photon subtraction relies on chiral optical waveguides, where a photon’s intrinsic spin dictates its direction of travel, enabling the selective removal of single photons from light pulses. This new module uses a solid-state quantum emitter integrated with the chiral waveguide to achieve photon subtraction, a technique that enhances the efficiency of quantum light production for applications ranging from secure communication to advanced sensing.
Sai Sreesh Venuturumilli, IQC PhD Candidate, explains that “If you can generate certain quantum states more efficiently, it has been shown that quantum computation and communication efficiency also increases.” This streamlined input allows for potential integration into existing systems, promising a boost in efficiency and scalability. Bajcsy says the experiment’s foundational work is already underway in his group, including the design and fabrication of the chiral waveguides in diamond.
The feasibility study has already yielded promising results, and the team is now transitioning to experimental realization of the system. “We have promising applications for this method and very tantalizing results from this feasibility study,” Bajcsy says.
“The exciting next step will be to realize this experimentally.” This research builds on Pasharavesh’s PhD work, moving beyond theoretical proposals to demonstrate a practical pathway for on-chip photon subtraction using currently available technology. The team’s work, co-authored with Golam Bappi, Supratik Sarkar and Dr. Jinjin Du, represents an advance in the development of compact and efficient quantum photonic hardware.
If you can produce quantum states efficiently with an on-chip photon subtraction module that only needs a simple laser as input, it can be plugged into existing systems and be more useful than other methods of producing quantum light, and this new paper shows how we can do this.
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