Researchers at the USC Viterbi Ming Hsieh Department of Electrical and Computer Engineering, along with the School of Advanced Computing, have created an optical filter that can isolate and preserve quantum entanglement. This development, published in Science, is expected to significantly improve quantum technologies used in computing, communication, and sensing.
The filter is made from laser-written glass light channels (waveguides) that remove unwanted components from light while maintaining the quantum correlations necessary for entanglement. According to Mahmoud A. Selim, a graduate student at USC, the filter refines quantum entanglement from a noisy state, keeping the quantum core intact while eliminating extraneous elements.
The filter uses anti-parity-time (APT) symmetry to manipulate light in new ways. By integrating APT symmetry into a network of optical waveguides, the team found a way to actively filter out noise, guiding the system toward a stable entangled state. Senior author Mercedeh Khajavikhan noted that this research demonstrates the potential of non-Hermitian physics and open quantum systems as tools in the quantum realm. Testing with single photons and entangled photon pairs confirmed the filter's ability to recover desired entangled states with over 99% fidelity.
This advancement has broad implications for quantum computing, quantum communication, and quantum sensing. The ability to scale and integrate this optical filter into existing quantum systems could revolutionize various industries and incorporate quantum technologies into everyday applications.