D-Wave Quantum annealer uses thousands of superconducting flux qubits on the lithography chip, suspended in an environment close to absolute zero. Image source: Network
When dealing with some complex tasks, quantum computer has an advantage over classic computers, but many challenges need to be overcome before fully realizing its potential. Physicists and computer scientists have been trying to truthfully evaluate the strength of quantum computing technology in the near future.
quantum simulation, that is, quantum systems implemented using programmable simulation devices, have been proven to be particularly valuable for judging the practical potential of quantum computers. One method that can be studied using Quantum simulation is quantum annealing, an optimization process based on engineering quantum fluctuations.
D-Wave and researchers in Canada, the United States and Japan recently simulated quantum phase transitions in a programmable 2,000 qubit one-dimensional Ising model. Their experimental results were published in Nature Physics, providing important value for future quantum optimization and simulation work. "Coherent annealing is something we have long wanted to show. It allows us to compare the behavior of programmable quantum systems with the ideal Schrödinger dynamics, providing strong evidence and benchmarks for quantum nature. For tasks that classical methods usually cannot solve, one-dimensional chains are ideal because they have well-known closed solutions, which means we can solve them in classical ways without the need to simulate quantum dynamics in detail." The quantum simulation of the one-dimensional Ising chain has been previously done by Harvard and other research teams. However, the simulations performed by King and his colleagues were the first to be performed using an annealing-based quantum computer. In addition, researchers were able to achieve larger and stronger correlation states.
simulation starts with the quantum paramagnetic superposition state and passes through the quantum phase transition at different speeds. As the system response time increases, a "knot" forms between the opposite domains of upward or downward rotation. The density and spacing of these kinks show the characteristics of quantum critical dynamics. (Image source: Internet)
King explains: "The key variable in our experiment is the annealing time, which is the time it takes for the D-Wave processor to go from its initial quantum overlay state to the classic endpoint of the calculation. Usually, the system sets a 500-nanosecond speed limit to allow the tolerance on the control circuit . However, in this work, we are 100 times faster than that. "
Because their system reaches higher speeds, King and his colleagues will be more stringent in hardware and use new software methods. Ultimately, they can perfectly synchronize thousands of qubits in the system.
researchers used a highly programmable processor created by the D-Wave system to perform simulations. To test its effectiveness more reliably, they chose to simulate an extremely simple and easy-to-understand quantum phase transition. "We see a high degree of consistency between experiments and ideal quantum models without environmental impact, which is a new development in the field of quantum annealing. Not only does it prove that the system is at the quantum level, but we can program more complex systems into quantum annealers, which will follow the real quantum dynamics of Schrödinger's equation, which is not usually simulated by classical."
In summary, the team found that their simulations are consistent with the predictions of quantum theory . In the future, their work can open up new achievements for the study of different quantum phase transformations. In the next work, King and his colleagues hope to use programmable D-Wave processors to simulate more peculiar quantum phase transitions that cannot be simulated using classical computers.
King adds: "Most people want to use quantum annealing for quantum simulations, or for optimization.The textbook quantum phase transitions we study in this work are only indirectly applicable to optimization, so it is important to link these two fields together. We already know that quantum annealers can solve optimization problems very quickly. Our next study will focus on coherent annealing to explain in detail the role of quantum critical dynamics in quantum annealing optimization. ”
Article reference link:
https://phys.org/news/2022-10-coherent-simulation-quantum-phase-transition.html
Compiled: Huike
edited: Muyi
edited: Muyi
