Mapping the quantum future with smart TV technology — ScienceDaily

Scientists have created the first-ever 2D map of the Overhauser field in organic LEDs, shedding light on the challenges we face in developing accurate quantum technologies

Previously, television was called a “box for idiots.” But the organic LEDs found in modern flat screens are far from stupid.

In fact, they help us draw a map that could open up a quantum future. No wonder they are now called smart TVs.

The new concept of quantum sensing has the potential to surpass existing technologies in a variety of fields, from electronics and magnetic field detection to microscopy, global positioning systems and seismology.

Taking advantage of quantum mechanics, new devices can be designed with unprecedented sensitivity and functionality.

But for this to happen, a deeper understanding of the role of spin, a fundamental quantum property of subatomic particles such as electrons, is required.

The spin of an electron can interact with other spins nearby through a process called ultrathin interaction.

In organic electronic materials, like those used in OLED displays, one electron will interact with the magnetic fields created by the many nuclear spins that are part of the molecule on which it sits. The cumulative effect is the Overhauser field.

So far, one value has been used to describe the strength of the Overhauser field in the device.

This approach is blind to local spin variations and does not reflect its true complexity, leading to uncertainty in how to reproduce and miniaturize devices that depend on spin behavior.

In an effort to address this uncertainty, researchers from the ARC Center for Excellence in Exciton Science have created the first-ever 2D map showing Overhauser’s field in OLED.

The team, based at UNSW Sydney, was able to achieve this by detecting microscopic changes in the magnetically increased brightness of OLED through the use of large magnetic fields, an effect known as magnetoelectroluminescence.

They were able to adjust these changes to the micrometer scale (one thousandth of a millimeter or 0.001 mm) and were able to map the spatial distribution of the Overhauser field strength.

Their results showed that this critical spin property varies by at least 30% in stable and widely used polymer OLED (SY-PPV) and by almost 60% in a device based on fluorescent fluorescent molecules (Alq3).

“These results highlight significant challenges that will need to be overcome in future attempts to reliably miniaturize organic sensing technologies for practical application,” said Professor Dane McKamy, who heads the research team at UNSW.

The first author of the article, Billy Papas, a graduate student at UNSW Sydney, said: “The miniaturization of organic devices is an important milestone in the ability to integrate them into functional quantum technologies, which then allow them to be effectively extended to industrial and commercial applications. .

“But if there’s a big variation in the features in a device that we’ve observed, the less you make them, the more that variation will affect your ability to play a device that behaves the same way.

“If you have 30% variation and you make two small devices, they will look the same, but they may behave completely differently. If you want to use them for sensation or logic, you won’t get the same results from two identical ones. otherwise devices due to this internal variation. “

It was also shown that the Overhauser field effect is “spatially correlated” (arranged as a template) at lengths of up to about seven micrometers. This opens up the possibility of producing devices on a length scale where this spin property is very uniform.

While this is useful information for future attempts to create devices aligned with the spins, there is a catch – the Overhauser field correlates only for a certain period of time before changing its distribution.

“We’ve noticed there’s a temporary component,” Billy said.

“So if you zoom in and sit in one particular region and repeat those measurements, you’ll see clusters, but they actually evolve over time, effectively changing their spatial distribution.

“These changes happen in a minute or two, so they’re very difficult to capture.”

The next step for researchers is to cool the OLED to very low temperatures with a cryostat to remove thermal vibrations before using a technique called optically detected magnetic resonance imaging (ODMR) to measure even more accurate spatiotemporal fluctuations of these spin properties.

Professor McCamy notes that “although this work highlights some of the challenges that need to be addressed to remanufacture devices, it is also incredible that the technology used in commercial OLED displays can be used to test these subtle quantum effects at room temperature.”

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