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Loophole-free Bell test – 2015

In 1935, Einstein asked a profound question about our understanding of Nature: are objects only influenced by their nearby environment? Or could, as predicted by quantum theory, looking at one object sometimes instantaneously affect another far-away object? We tried to answer that question, by performing a loophole-free Bell test.

Loophole-free Bell test - 2015

Below you can find relevant articles, an image gallery and video gallery. Please click on the image or link to get more information and high resolution. The material may be used free of royalties for purposes of news items when adding image authorship.

Press Release and News Items

Scientific article

Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres
B. Hensen, H. Bernien, A.E. Dréau, A. Reiserer, N. Kalb, M.S. Blok, J. Ruitenberg, R.F.L. Vermeulen, R.N. Schouten, C. Abellán, W. Amaya, V. Pruneri, M. W. Mitchell, M. Markham, D.J. Twitchen, D. Elkouss, S. Wehner, T.H. Taminiau, R. Hanson
Nature, published online October 21, 2015.

DOI: 10.1038/nature.15759
link to online article


Prof. Dr. Ir. Ronald Hanson in his lab at location A of the Bell test. Photo: QuTech

Part of the Bell test setup, at location A. This image shows the experimental setup that houses the diamonds used in the Bell test. The diamonds are hosted in a low-temperature microscope, that can be seen on the far left of the image. Photo: Frank Auperle.
This image shows the heart of the entanglement generation: the beam-splitter and photon detectors, housed in the middle of the campus, at location C. Photo: Frank Auperle.

This image is an electron microscope picture of one of the two devices, with a fictitious laserbeam added. The image is about 40 micrometer wide in reality. Image: HansonLab@TUDelft

A forest of optical elements to guide single photons from- and laser beams to each diamond. Photo: Frank Auperle.

First author Ir. Bas Hensen and Prof. Dr. Ir. Ronald Hanson adjusting the Bell test setup at location A. Photo: Frank Auperle.


Aerial view of the campus, with location of the labs highlighted. On the far left is location A, housing one of the two diamonds. The other diamond is housed on the other end of the campus, on the right of the photo. The beam-spliter, at location C, is located in the middle. Aerial photograph: Slagboom en Peeters Luchtfotografie BV.


In this animation, a short overview of the concepts and history of the Bell test is given, and how our experimental result fits in the story.

This animation explains how the Bell test works.