Scalable Multipartite Entanglement Achieved with Ultracold Atoms in Optical Lattice

Researchers from the University of Science and Technology of China (USTC) have made significant progress in preparing and measuring scalable multipartite entangled states. Working with researchers from Tsinghua University and Fudan University, the team used ultra-cold atoms trapped in optical lattices to create multi-atom entangled states.

Quantum entanglement is a fundamental phenomenon in quantum computing, and the ability to prepare, measure, and manipulate large-scale entangled states is crucial for advancing quantum research. Ultracold atomic qubits in optical lattices provide excellent coherence, scalability, and quantum control, making them an ideal choice for quantum information processing.

The USTC research team has been studying various aspects of optical lattices since 2010, including multibody phase transitions, atomic interactions, and entropy distribution dynamics. In 2020, they achieved an entanglement fidelity of 99.3% with over 1,000 pairs of entangled atoms, laying the foundation for larger multi-atom entangled states and further quantum computing research.

To overcome technical challenges such as limited control over individual atomic qubits and phase shifts in optical lattices, the team developed a new equal-arm, cross-beam interference, and spin-dependent superlattice system. This system, combined with advanced microscopy and spot shape editing techniques, allowed for precise measurement and control of multi-atom entanglement states.

Using this setup, the researchers achieved a 99.2% filling rate of a two-dimensional atomic array and prepared entangled Bell states with an average fidelity of 95.6% and a lifespan of 2.2 seconds. They also connected adjacent entangled pairs to create a 10-atom one-dimensional entangled chain and an eight-atom two-dimensional entangled block.

This achievement represents a significant step toward large-scale quantum computation and simulation using optical lattices. The research is published in Physical Review Letters.

– Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.131.073401
– University of Science and Technology of China