IBM, investing significant resources in the development of quantum computing technology, recently made a breakthrough in quantum computing research. In a recent publication in the scientific journal "Nature," IBM researchers utilized the 127-qubit IBM Quantum Eagle processor to conduct complex physical simulations, achieving consistent and accurate results surpassing classical computers. This achievement signifies a key milestone in proving the superiority of quantum computers over classical counterparts and marks the era of Quantum Advantage for humanity.
Previously, scientists lacked confidence in quantum computers due to the challenge of mitigating the impact of noise in quantum computing systems. The noise in quantum computers can lead to deviations from the true numerical values in simulations. Additionally, scientists faced the task of devising methods to address noise and expanding these approaches to overcome noise issues in computers with larger qubit systems.
The research team discovered a technique called Pulse Stretching, which holds promise in effectively addressing noise issues. The core idea of this method lies in understanding the nature of noise and its causes within quantum computer systems to find ways to eliminate it.
In quantum computing, pulses refer to electromagnetic pulses used to manipulate and control qubits. Specific electromagnetic pulses are required to change the state of qubits or perform more complex operations such as superposition and entanglement during quantum computations.
Pulse stretching involves extending the duration of electromagnetic pulses, thereby amplifying the noise present in the control system. By doubling the duration of operations, scientists can observe and measure noise more easily, understand its effects, and work towards its elimination.
However, pulse stretching alone does not achieve the desired level of accuracy. The research team also employed a method called Probabilistic Error Cancellation to comprehend the fundamental hardware noise of quantum computers. They created noise representative models and controlled noise by inserting new quantum gates into the system. By combining this approach with Zero Noise Extrapolation (ZNE) and advanced post-processing techniques, they achieved more precise operations, amplified noise, and extrapolated results free from the influence of noise.
In addition to methodological improvements, the capabilities of quantum hardware play a crucial role in error resolution. Only with the current 127-qubit IBM Quantum Eagle processor has quantum computing truly gained the ability to challenge the limits of classical computers and achieve superior computational speed and results.
To validate their quantum computer research, IBM invited researchers from Berkeley University to verify the computational outcomes using classical computers. While classical computers can accurately calculate answers for smaller quantum circuits through brute force methods, as the number of qubits increases, the complexity of quantum circuits surpasses the capture capacity of classical computers. To address this, Berkeley researchers developed a method called Tensor Network State (TNS) that enables effective simulations even when brute force methods fail, albeit with some loss of information.
The classical computations were performed on supercomputers at NERSC and Purdue University, and the results were compared with those obtained from the quantum computer. The findings revealed consistent outcomes between quantum and classical methods. As complexity increased, exceeding the realm where classical computers could provide accurate answers, quantum computers continued to yield results. Although scientists could not verify the correctness of these answers, multiple rounds of experiments instilled confidence in the accuracy of quantum computer results.
The significance of this research lies in demonstrating the existence of quantum advantage. To establish quantum superiority, scientists must confirm two aspects: first, proving that quantum computers can outperform classical computers, and second, identifying problems that can be effectively solved using quantum advantage and mapping these problems onto qubits. IBM's research has already achieved the first point, instilling greater confidence in quantum computing among scientists and even positioning quantum computers as validation tools for classical computations.