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Defect-free assembly of 2-D clusters with more than 100 single-atom quantum systems

** Defect-free badembly of 2-D clusters with more than 100 single-atom quantum systems

Atomic pattern set: an initial atom distribution with defects is transferred to a target group of 100 atoms without defects through the transport of a single atom. Credit: Gerhard Birkl

Researchers at the Darmstadt University of Technology have recently demonstrated the flawless badembly of versatile target patterns of up to 111 single-atom quantum systems. Their findings, summarized in an article published in Physical revision letters, could push the architectures of atoms badembled beyond the threshold of quantum advantage, paving the way for new advances in quantum science and technology.

"Our research is based on the observation that the physical sciences are right in the middle of a paradigm shift in which the application of quantum physics, that is, quantum technologies, are becoming the leading technologies in the near future "said Gerhard Birkl, one of the researchers. Who carried out the study, told Phys.org. "You can already foresee a wide list of applications, but I am convinced that most of the applications do not even know".

The next step for the field of quantum science and technology is the development of experimental platforms that offer extensive scalability, multisite quantum correlations and efficient quantum error correction. Over the last century or so, researchers have done a substantial amount of work on unique quantum systems, laying the foundation for current developments. Atomic quantum systems have played a key role in these studies, particularly neutral atoms trapped by light, as they provide well-isolated quantum systems with a favorable scale.

"For the next generations of quantum technologies, going to multiple quantum systems, that is, scaling the size of the system is fundamental," Birkl said. "For that reason, we gave ourselves the directive to develop a novel platform that provides highly scalable architectures for atomic quantum systems with total control of all relevant parameters for the advancement of cutting-edge quantum technologies."

In developing the technological basis for their experiment, Birkl and his students who participated in the study focused on neutral atoms cooled by laser and optical traps, as they benefit from the scientific advances of the last 25 years. These advances include cooling and laser capture, Bose-Einstein condensation, manipulation of individual quantum systems and optical tweezers.

"Finally, we realized that the combination of these scientific developments with advanced optical technologies, such as microfabrication of large-scale microlens arrays, creates an ideal platform for the advancement of scalable quantum technologies," said Birkl. "It is fundamental for our work that we apply a novel experimental architecture in which we generate a 2D pattern of optical traps for neutral atoms based on 2-D microlens arrays."

Using a large laser beam that illuminates many lenses, the researchers were able to generate several laser traps simultaneously. They generated up to 400 of these traps in parallel and then were able to tackle them individually.

His experiment took several steps. Birkl and his colleagues started creating a cloud of rubidium atoms in a vacuum system at room temperature, using a magneto-optical trap (MOT). This allowed them to generate several million rubidium atoms at a temperature of approximately 100 microKelvin. Later, they activated the pattern of the laser traps and transferred the atoms to these traps, with a maximum of 1 atom per trap.

** Defect-free badembly of 2-D clusters with more than 100 single-atom quantum systems

Central part of the experimental apparatus for the disposition of rubidium atoms in 2D white patterns without defects. The blue laser light is used to initiate coherent quantum operations. Credit: Gerhard Birkl

"We generate patterns that consist of capture sites with exactly one or zero atoms," explained Birkl. "Next, we took an image of the pattern and this allowed us to identify the occupied sites (which did not require more action) and the empty sites".

Once they determined which sites were occupied and which were empty, the researchers filled all the empty sites; Collect a single atom from a full site out of the target pattern and transport it to an empty site in the target pattern. This transport process was carried out using a single focus laser beam that could move in 2-D through the entire trap array.

"This works like tweezers made of light, so they are called 'optical tweezers' and are an invention of Dr. Arthur Ashkin, who received part of the 2018 Nobel Prize in Physics for this invention," he said. Birkl. "After applying the clamps for all the empty sites, we take another image of the distribution of atoms and determine the success of the process of generation of defect-free atom patterns, in case we still have empty sites, we repeat the badembly process once again, you can do this up to 80 times in an experimental execution, which is another reason for our success in generating large flawless patterns with high probability. "

In their study, the researchers operated a large number of traps (361), placed in a square grid of 19×19, which corresponded to a substantial number of individual atoms (approximately 200) and this allowed them to repeat the badembly process several times. All these factors finally helped break the previous record for the badembly of quantum systems of a single atom.

"The scalability of the physical systems used is critical for further progress in this field," Birkl said. "We were able to significantly increase the size of the pattern and the probability of success of the systems based on neutral atoms.No related experiment has shown more than 72 qubits before, of course, more than 100, or even 111. Our platform has the perspective explicit of being scalable even beyond those numbers. "

Quantum supremacy generally requires more than 50 qubits, but so far only a few quantum technology experiments were able to overcome this threshold. In their experiment, the researchers reached a total of 111 qubits with a clear plan of how to overcome this number. This is evidence of the scalability of its experimental platform.

"In addition, we could enter the regime of quantum supremacy with high success rates, since we demonstrated a success rate of more than 60% for a pattern with 8×8 = 64 qubits," Birkl added. "With the duration of an experimental execution of 1 second, this gives a new defect-free configuration for quantum processing in the regime of quantum supremacy every two seconds."

The study by Birkl and his team could have important implications for several subfields of quantum technology research, including quantum simulation and quantum computing. The researchers now plan to scale their platform to 1000 quantum systems, in addition to adding the ability to initiate quantum gates of two qubits between atoms to build a 2D quantum processor based on Rydberg's interactions. In this way, they also hope to implement quantum computing on a large scale and quantum simulations using their experimental platform.

Researchers break the record of atoms placed individually in a trap to create flawless arrays

More information:
Daniel Ohl de Mello et al. Assembly without defects of 2D groups of more than 100 Quantum systems of a single atom, Physical revision letters (2019). DOI: 10.1103 / PhysRevLett.122.203601

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The free badembly of defects of 2-D groups with more than 100 quantum systems of a single atom (2019, May 31)
recovered on May 31, 2019
from https://phys.org/news/2019-05-defect-free-d-clusters-single-atom-quantum.html

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