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The experimental setup used in the study. Credit: Jonas S. Neergaard-Nielsen.
Quantum-enhanced metrology has been an active area of research for several years now due to its many possible applications, ranging from atomic clocks to biological imaging. Past physics research established that having a non-classical probe, such as squeezed light or an entangled spin state, can have significant benefits compared to classical probes. This idea was explored further in several recent works, some of which also considered the benefits of examining multiple distinct samples with non-classical probes.
Studies - Researchers - Technical - University - Denmark
Inspired by these studies, researchers at the Technical University of Denmark and the University of Copenhagen have recently carried out an experiment investigating the advantages of using an entangled quantum network to sense an averaged phase shift among multiple distributed nodes. Their paper, published in Nature Physics, introduces a series of techniques that could help to collect more precise measurements in a variety of areas.
"Recent studies showed that having non-classical correlations between probes addressing different samples could lead to a gain compared to having non-correlated probes," Johannes Borregaard, the researcher who initiated the project, told Phys.org. "This inspired us to investigate whether such advantages could be demonstrated already using present technology."
Study - Borregaard - Colleagues - Light - Detection
In their study, Borregaard and his colleagues focused on squeezed light and homodyne detection, which are now established sensing techniques. The overall goal of the experiment was to measure a global property of multiple spatially separated objects and investigate whether probing these objects simultaneously with entangled light led to more precise results than probing them individually. The researchers found that the use of a quantum network to probe the objects simultaneously enabled phase sensing with far higher precision than that attainable when examining probes individually.
Outline of the scheme for distributed phase sensing. Squeezed light (sqz) is distributed via beam-splitters to the phase samples under study....
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