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Single-Photon Detector Can Count to Four


Three photons passing through a superconducting nanowire.

Researchers at Duke University, Ohio State University, and Quantum Opus have demonstrated that a widely used method of detecting single photons can also count the presence of at least four photons at a time.

Credit: Duke University News

Researchers at Duke University, Ohio State University, and Quantum Opus have demonstrated that a widely used method of detecting single photons can also count the presence of at least four photons at a time, which should unlock new capabilities in physics labs working in quantum information science and deliver easier pathways to developing quantum-based technologies.

The group used a superconducting nanowire single-photon detector, which functions by charging a looped segment of superconducting wire with an electric current near its maximum limit. When a photon passes, it induces a decline in that maximum limit in a small portion of the wire, causing a brief loss of superconductivity that subsequently generates an electrical signal to mark the photon's presence.

By noting the specific configuration of the initial spike in the electrical signal, the researchers found they could collect sufficient detail to correctly count at least four photons traveling together in a packet.

From Duke University News
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