Quantum computers have the potential to revolutionize various industries due to their ability to tackle complex issues. However, these computers have inherent flaws that limit their functionality. To address this challenge, researchers at Caltech have developed a groundbreaking technique that allows classical computers to assess error rates in quantum machines without the need for full simulations.
Traditionally, investigating faults in quantum systems required modeling them on classical computers, which could be impractical given the complexity of quantum machines. The new technique is more efficient, enabling the measurement of error rates by traditional computers without lengthy simulations.
In their recent study, researchers conducted experiments on a specific type of quantum computer known as a quantum simulator. Quantum simulators, unlike current basic quantum computers, are more specialized and have a narrower operational scope. By manipulating highly excited Rydberg atoms in individual controllable states using lasers, the group created their quantum simulator.
One key feature of the simulator is entanglement, which emerges spontaneously as quantum computers perform tasks, gradually connecting the atoms. Researchers found that as entanglement increases, these connections disperse in a chaotic manner, indicating that minor disturbances can have significant effects, similar to the butterfly effect in global weather patterns.
Despite their increasing complexity, quantum computers are expected to solve certain problems much faster than classical computers, such as cryptographic tasks that involve rapid factorization of large numbers.
However, classical computers reach their limits in simulating machines once they exceed a certain number of qubits or coupled atoms. The complexity of calculations grows exponentially with the number of qubits and entanglement levels.
The new quantum simulator features 60 qubits, placing it in a realm that is impossible to simulate using classical computers. Researchers aimed to create a system that challenges classical computers but still relies on them to validate the quantum simulator.
This innovative approach involves running classical computer simulations with varying levels of entanglement.
Lead author Adam Shaw, a graduate student in Manuel Endres’s laboratory, explained the concept using an analogy of painting the Mona Lisa. He highlighted the need for classical computers to simulate the quantum computer’s work to quantify errors accurately.
The researchers estimated that their 60-qubit quantum simulator operates with a 91% error rate, which is relatively high in the field. This benchmark allows for the analysis of errors in quantum computing systems and the measurement of entanglement levels in quantum simulations.
Shaw emphasized the significance of this benchmark for evaluating hardware improvements and the success of quantum simulations.
Journal Reference:
- Shaw, A.L., Chen, Z., Choi, J., et al. Benchmarking highly entangled states on a 60-atom analogue quantum simulator. Nature (2024). DOI: 10.1038/s41586-024-07173-x
