Stretched diamonds for more efficient and economical qubits – Enerzine

In a new study supported by the Q-NEXT Quantum Research Center, researchers have managed to “stretch” diamond films to create qubits that are more economical and easier to control. This discovery could make future quantum networks more practical.

A team of researchers from the U.S. Department of Energy’s Argonne National Laboratory, the University of Chicago and the University of Cambridge announced a significant discovery in quantum networking technology.

By “stretching” thin diamond films, they created quantum bits that can be operated with significantly less equipment and cost. This change also makes it easier to control the bits.

The researchers hope that the results, published in Physical Review X, can make future quantum networks more practical. “This technique allows you to significantly increase the operating temperature of these systems, to the point where their operation is much less resource intensive,” commented Alex High, an assistant professor at the Pritzker School of Molecular Engineering at UChicago, whose lab led the study.

Diamond expansion

Quantum bits, or qubits, have unique properties that make them interesting to scientists looking for the future of computer networks. For example, they could be made virtually impenetrable to hacker attacks. However, there are still significant challenges that need to be solved before it can become mainstream and everyday technology.

One of the main problems lies in the “nodes” that would pass information along a quantum network. The qubits that make up these nodes are very sensitive to heat and vibrations, so scientists need to cool them to extremely low temperatures in order for them to work.

“Today, most qubits require a special room-sized refrigerator and a team of highly trained people to run it. So if you imagine an industrial quantum network where you would have to build one every five or ten kilometers, now you’re talking about a lot of infrastructure and work,” said Alex High.

Experimenting with materials

High’s lab worked with Argonne researchers to experiment with the materials used to make these qubits to see if they could improve the technology.

One of the most promising types of qubits is made from diamonds. These qubits, known as “Group IV color centers,” are known for their ability to maintain quantum entanglement over relatively long periods of time. To do this, however, they must be cooled to slightly more than absolute zero.

The team wanted to experiment with the material’s structure to see what improvements could be made – a difficult task given the hardness of diamonds. However, scientists discovered that by placing a thin film of diamond on hot glass, they could “stretch” diamonds at the molecular level. As the glass cools, it shrinks more slowly than the diamond, causing the diamond’s atomic structure to stretch slightly – just as cobblestone expands or contracts as the earth beneath it cools or warms, High explained.

Effects of stretching

Although this stretching only moves the atoms apart by an infinitesimally small distance, it has dramatic effects on the behavior of the material.

First, qubits can now maintain coherence at temperatures as low as 4 Kelvin (or -452°F or -233°C). It is still very cold but can be reached with less specialist equipment.

“It’s an order of magnitude difference in terms of infrastructure and operating costs,” Alex High added.

Second, the change also allows qubits to be controlled with microwaves. Previous versions had to use light in the optical wavelength to enter information and manipulate the system, which introduced noise and meant reliability was not perfect. However, with the new system and microwaves, the fidelity increased to 99%.

It’s unusual to see improvements in both areas at the same time, said Xinghan Guo, a physics graduate student in High’s lab and lead author of the paper.

“If a system typically has a longer coherence lifetime, it is because it is good at ‘ignoring’ external disturbances – meaning that it is more difficult to control because it is resistant to these disturbances,” he said again. “It is very exciting that we have been able to overcome this dilemma through a very fundamental innovation in materials science. »

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This research has made it possible to take a significant step towards the realization of more practical and economical quantum networks. By “stretching” diamond films, researchers were able to create diamonds Qubits which can be operated with considerably less equipment and costs and at the same time is easier to control.

For better understanding

What is a Qubit?

A qubit or quantum bit is the basic unit of information in quantum computing, analogous to the bit in classical computing.

What is quantum entanglement?

Quantum entanglement is a phenomenon that occurs when particles become connected and the state of one directly affects the state of the other, regardless of the distance between them.

What is the Q-NEXT Quantum Research Center?

Q-NEXT is a quantum research center that supports research in the field of quantum information.

What does diamond have to do with qubits?

Diamonds are used to create a type of qubit known as “Group IV color centers.” These qubits are known for their ability to maintain quantum entanglement for relatively long periods of time.

What is the Diamond Stretching Technique?

In the diamond “stretching” technique, a thin film of diamond is placed on hot glass. As the glass cools, it shrinks more slowly than the diamond, stretching the diamond’s atomic structure slightly.

Main lessons

References

Caption: By “stretching” thin layers of diamond, researchers have created quantum bits that can be operated with significantly reduced equipment and costs. (Illustration by Peter Allen)

The information in this article is based on a study published in Physical Review.

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