Now researchers at the University of Ottawa in Canada and Sapienza University in Rome have developed a new technique that can visualize this entanglement in record time.
in Article in Nature Photonics They describe how, using a method they call two-photon digital holography, they created a yin-and-yang-like image of two entangled light particles in record time.
Quantum entanglement is difficult to capture
In short, quantum entanglement means that two particles can be linked together over large distances.
This means that, for example, two particles of light – also known as photons – can behave in such a way that when a change occurs in one particle, a corresponding change occurs in the other.
In order to predict how a quantum object such as photons will behave, physicists must find the wave function of that object.
This wave function is a description of the state of the particle, which exists at the quantum level in what is called superposition. This means that a particle can be in all physical states at the same time.
Therefore, finding the wave function of two coupled particles is a major challenge, since any measurement of one particle leads to an instantaneous change in the other.
To solve this challenge, physicists are using a method called quantum tomography, which can create 3D reconstructions of particles using measurements.
To do this, physicists must make many measurements of the particles’ quantum state, and the more complex the state, the more measurements they need. Based on the measurements, they can reconstruct a 3D object for entanglement based on predictions.
In a press release Researchers compare it to recreating a three-dimensional object from two-dimensional shadows.
Although this method provides accurate results, it also creates many results that are not physically possible and must be discarded to obtain an accurate image, a process that may take several days.
The intertwining of yin and yang
Finally we come to the new method: two-photon digital holography. Stereograms are two-dimensional representations of three-dimensional objects.
Optical holograms use two beams of light to create a 3D image. One ray strikes the object that reflects the ray. The second beam hits the super high-resolution camera.
The hologram consists of the pattern that is formed as a result of interference, that is, the wave peaks and valleys in the two light waves reinforce or cancel each other.
Using this method and a nanosecond camera, the researchers were able to characterize the received interference pattern by comparing the unknown quantum state with a known state, revealing a yin-yang-like reconstruction of the two entangled photons.
“This method is significantly faster than previous techniques and requires only minutes or seconds instead of days,” says one of the researchers behind the new technique, Alessio d’Errico of the University of Ottawa, in the press release.
Quantum entanglement is one of the fundamental elements of quantum computers. A better understanding of entanglement could lead to more stable quantum computers.
The researchers wrote in the article that the shape of yin and yang came about by chance due to the angle of light rays. In Chinese philosophy, yin and yang describe opposite but interconnected forces, such as light and darkness, order and chaos.
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