For the First Time, Scientists Detect a Moving Photon Multiple Times Without Destroying ItBoon for all things quantumBy Charles Q. Choi
09 Jul 2021 | 12:00 GMT
MAX PLANCK INSTITUTE OF QUANTUM OPTICS
A view of one of the research team's two vacuum chambers. Inside one can see the mount of the cavity (rectangular metal box). In the mount, one can see two conically shaped objects in white. These are the two cavity mirrors. The distance between the mirrors is 0.5 millimeters, and the scientists trap a single rubidium atom between these mirrors.The act of detecting a photon typically destroys it. Now scientists have for the first time nondestructively detected a single traveling photon not just once, but multiple times. Such research could make future quantum communications networks and quantum computers faster and more robust, they say.
Quantum communications networks are in principle virtually unhackable, and quantum computers theoretically can be more powerful than any supercomputer. These devices often use photons for communications or computations.
Detecting photons typically requires absorbing them. However, in some applications, a single photon may carry valuable information, such as data needed for a quantum computation. In such cases, scientists would like to read out the photon's data but also keep track of the photon as it travels in order to make sure it reaches its final destination successfully.
"No detector is ever 100% efficient—there's always a chance may slip through not detected," says study senior author Stephan Welte, a quantum physicist at the Max Planck Institute for Quantum Optics in Garching, Germany. With more than one detector linked together in a series, "you enhance the chance of detection."
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https://spectrum.ieee.org/tech-talk/semiconductors/optoelectronics/photons-trace-twice
