Photon subtraction approach shows a novel method for producing quantum light
IQC researchers outline on-chip module in new paper
By Naomi Grosman
Researchers at the Institute for Quantum Computing (IQC) at the University of Waterloo have shown the experimental feasibility of subtracting photons, single units of light, from incoming light pulses. They achieved this using a solid-state quantum emitter and a unique type of optical waveguide integrated on a chip.
This new approach can be plugged into existing systems, potentially increasing efficiency in current methods of producing quantum light for technologies such as quantum communications, sensing, and even computing.
Dr. Michal Bajcsy, IQC faculty and Professor, Department of Electrical and Computer Engineering, led the research which proposes a system that removes a single photon from a light pulse using a quantum emitter and a chiral optical waveguide — a unique class of optical waveguides in which the spin of photons determines whether they travel forward or backward.
“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. It will be a challenge to bring the parts together but with current available tools we are at the point that we are working on proof-of-principle experimental studies and exploring how to make this into a scalable platform.”
- Dr. Michal Bajcsy, IQC Faculty and Professor, Department of Electrical and Computer Engineering
A visualization of a photon-subtraction module based on solid-state emitters coupled to a chiral waveguide. From Pasharavesh's PhD work at IQC.
The paper is based on Abdolreza Pasharavesh’s PhD research at IQC, where he is now a Postdoctoral Fellow. He proposed that if you carefully measure the subtracted photon or cascade multiple photon subtraction stages, you can generate arbitrary quantum states of light out of simple laser pulses. The new study takes Pasharavesh’s theoretical proposal a step further to show how this could be done in practice with currently available technology.
“If you can generate certain quantum states more efficiently, it has been shown that quantum computation and communication efficiency also increases. This is why photon subtraction is a useful research area for the development of quantum photonic hardware platforms.”
- Sai Sreesh Venuturumilli, IQC PhD Candidate
Bajcsy says the experiment’s foundational work is already underway in his group, such as the design and fabrication of the chiral waveguides in diamond.
“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.”
The paper was published in NPJ Quantum Information. The paper’s co-authors are Bajcsy, Pasharavesh, Venuturumilli, as well as Golam Bappi and Supratik Sarkar, master’s students at the time of the research, and Dr. Jinjin Du, who was Postdoctoral Fellow.