{"id":689858,"date":"2025-09-13T11:25:26","date_gmt":"2025-09-13T08:25:26","guid":{"rendered":"https:\/\/buradabiliyorum.com\/en\/seeing-a-trio-of-entangled-photons-in-one-go\/"},"modified":"2025-09-13T11:25:26","modified_gmt":"2025-09-13T08:25:26","slug":"seeing-a-trio-of-entangled-photons-in-one-go","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/seeing-a-trio-of-entangled-photons-in-one-go\/","title":{"rendered":"Seeing a trio of entangled photons in one go"},"content":{"rendered":"
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\n Achieving the entanglement measurement of the W state. Credit: KyotoU \/ Takeuchi lab
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The concept of quantum entanglement is emblematic of the gap between classical and quantum physics. Referring to a situation in which it is impossible to describe the physics of each photon separately, this key characteristic of quantum mechanics defies the classical expectation that each particle should have a reality of its own, which gravely concerned Einstein.<\/p>\n

Understanding the potential of this concept is essential for the realization of powerful new quantum technologies.<\/p>\n

Developing such technologies will require the ability to freely generate a multi-photon quantum entangled state, and then to efficiently identify what kind of entangled state is present. However, when performing conventional quantum tomography, a method commonly used for state estimation, the number of measurements required grows exponentially with the number of photons, posing a significant data collection problem.<\/p>\n

If available, an entangled measurement can identify the entangled state with a one-shot app<\/a>roach. Such a measurement for the Greenberger-Horne-Zeilinger\u2014GHZ\u2014entangled quantum state has been realized, but for the W state, the other representative entangled multi-photon state, it has been neither proposed nor discovered experimentally.<\/p>\n

This motivated a team of researchers at Kyoto University and Hiroshima University to take on this challenge, ultimately succeeding in developing a new method of entangled measurement to identify the W state. The paper is published<\/a> in the journal Science<\/a> Advances<\/i>.<\/p>\n

“More than 25 years after the initial proposal concerning the entangled measurement for GHZ states, we have finally obtained the entangled measurement for the W state as well, with genuine experimental demonstration for 3-photon W states,” says corresponding author Shigeki Takeuchi.<\/p>\n

The team focused on the characteristics of the W state’s cyclic shift symmetry, and theoretically proposed a method to create an entangled measurement using a photonic quantum circuit that performs quantum Fourier transformation for the W state of any number of photons.<\/p>\n

They created a device to demonstrate the proposed method for three photons using high-stability optical quantum circuits, which allowed the device to operate stably without active control for an extended period of time.<\/p>\n

By inserting three single photons into the device in appropriate polarization states, the team was able to demonstrate that the device can distinguish different types of three-photon W states, each corresponding to a specific non-classical correlation between the three input photons.<\/p>\n

The researchers were able to evaluate the fidelity of the entangled measurement, which is equal to the probability of obtaining the correct result for a pure W-state input.<\/p>\n

This achievement opens the door for quantum teleportation, or the transfer of quantum information. It could also lead to new quantum communication protocols, the transfer of multi-photon quantum entangled states, and new methods for measurement-based quantum computing.<\/p>\n

“In order to accelerate the research and development of quantum technologies, it is crucial to deepen our understanding of basic concepts to come up with innovative ideas,” says Takeuchi.<\/p>\n

In the future, the team aims to apply their method to a larger-scale, more general<\/a> multi-photon quantum entangled state, and plans to develop on-chip photonic quantum circuits for entangled measurements.<\/p>\n

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More information:<\/strong>
\n\t\t\t\t\t\t\t\t\t\t\t\tGeobae Park et al, Entangled Measurement for W states, Science Advances<\/i> (2025). DOI: 10.1126\/sciadv.adx4180<\/a>. www.science.org\/doi\/10.1126\/sciadv.adx4180<\/a><\/p>\n<\/p><\/div>\n

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\n\t\t\t\t\t\t\t\t\t\t\t\t\tProvided by
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tKyoto University
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n<\/p><\/div>\n

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\n\t\t\t\t\t\t\t\t\t\t\t\tCitation<\/strong>:
\n\t\t\t\t\t\t\t\t\t\t\t\tMeasuring the quantum W state: Seeing a trio of entangled photons in one go (2025, September 12)
\n\t\t\t\t\t\t\t\t\t\t\t\tretrieved 13 September 2025
\n\t\t\t\t\t\t\t\t\t\t\t\tfrom https:\/\/phys.org\/news<\/a>\/2025-09-quantum-state-trio-entangled-photons.html\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n

\n\t\t\t\t\t\t\t\t\t\t\t This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
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