Researchers from the University of Science and Technology of China (USTC) have made significant strides in the field of quantum research by achieving scalable multipartite entanglement using ultracold atoms in optical lattices. Led by scientists from USTC, Tsinghua University, and Fudan University, the team successfully prepared and measured entangled states of multiple atoms.

Quantum entanglement is a fundamental phenomenon that underlies the principles of quantum computing. The ability to create entangled qubits is crucial for the exponential growth of computing capabilities. However, the preparation, measurement, and manipulation of large-scale entangled states pose significant challenges.

Ultracold atomic qubits in optical lattices have emerged as a promising candidate for quantum information processing due to their excellent coherence, scalability, and precise quantum control. The USTC research team has been studying multibody phase transitions, atomic interactions, and entropy distribution dynamics in optical lattices since 2010.

By 2020, the team had achieved remarkable progress, attaining an entanglement fidelity of 99.3% with over 1,000 pairs of entangled atoms. This paved the way for the enhancement of atomic entanglement fidelity and parallel atomic control, creating a foundation for larger multi-atom entangled states and further quantum computing research.

To overcome technical obstacles, the research team developed a new system that incorporated an equal-arm cross-beam interference and spin-dependent superlattice. The system allowed for precise measurement and control of both single grid points and global parallel measurements of multi-atom entanglement.

Through this innovative approach, the researchers achieved a 99.2% filling rate of a two-dimensional atomic array. They successfully prepared entangled Bell states with an average fidelity of 95.6% and a lifespan of 2.2 seconds. Additionally, they connected adjacent entangled pairs, forming a 10-atom one-dimensional entangled chain and an eight-atom two-dimensional entangled block.

This breakthrough represents a significant step toward the realization of large-scale quantum computation and simulation using optical lattices. The findings of this research have been published in Physical Review Letters.

### Frequently Asked Questions (FAQ)

#### What is quantum entanglement?

Quantum entanglement is a phenomenon in quantum physics where two or more particles become connected in such a way that their states are dependent on each other, regardless of the distance between them. Changes to the state of one particle will affect the state of the other, even if they are far apart.

#### Why is scalable multipartite entanglement important?

Scalable multipartite entanglement is crucial for quantum computing because it enables exponential growth in computing capabilities. The ability to entangle multiple qubits allows for more complex quantum computations and a greater potential for solving complex problems efficiently.

#### What are ultracold atoms in optical lattices?

Ultracold atoms are atoms that have been cooled to extremely low temperatures, typically just above absolute zero. Optical lattices are created by trapping these ultracold atoms in an arrangement of laser beams, which form a periodic potential. This configuration allows for precise control and manipulation of the atoms’ quantum states.

#### How does this research contribute to quantum computing?

This research contributes to the development of quantum computing by demonstrating the successful creation and measurement of large-scale entangled states using ultracold atoms. The ability to prepare and control these entangled states is a crucial step toward harnessing the power of quantum computing for practical applications.