The grid code, represented by the cube’s faces, is used to include a logical qubit into the state space of a harmonic oscillator. These grid states are safeguarded from contamination by a noisy environment, represented by the ray, thanks to quantum error correction.
Researchers have reached a critical milestone in quantum computing by utilizing Quantum Error Correction to increase the lifetime of quantum information over the breakeven point, paving the way for efficient quantum information processing in the presence of noise found in real-world settings.
Understanding Decoherence and Quantum Error Correction
Classical behavior emerges from quantum principles of nature, and this is the phenomena known as decoherence. Using these rules for information processing, particularly in the realm of quantum computing, is complicated by the quantum-classical interface. Qubits in a quantum computer can lose information if their quantum states are disturbed by external factors like stray radiation.
The Breakeven Point and Quantum Error Correction
Quantum Error Correction (QEC) is used to lessen the impact of decoherence. However, due to the fact that the rate of error correction was slower than the rate of decoherence, most prior experimental attempts to use QEC were failed. As a result, the quantum system experienced data loss at a rate greater than that which could be restored by QEC. ‘Breakeven’ refers to the point where the extra complexity of the correction circuit just about cancels out the produced decoherence.
Extended Lifetimes and New Possibilities
Scientists have performed a remarkable experiment by doubling the lifetime of quantum information past the breakeven threshold. The significance of this result lies in the fact that it dispels the myth that there are inherent obstacles to actively prolonging the lifespan of quantum information. This practical success confirms the theoretical predictions of scientists and prepares the way for the processing of quantum information in the presence of noise from radiation, cosmic rays, and other sources.
Looking Forward: Error-Corrected Qubits and Real-World Challenges
Realizing high-fidelity logical operations between two error-corrected qubits is the next hurdle for this research platform, given that noise is an inevitable part of life for quantum systems in the real world.
Implementing Grid Code in Quantum Experiments
The grid code was implemented inside of an electromagnetic mode in a superconducting cavity for the experiment. An extra superconducting circuit called the transmon controls the quantum state of this mode. Scientists used a dilution refrigerator to cool the system to a temperature one hundred times lower than the cosmic background radiation in space. In just a few hundred nanoseconds, an external controller managed the quantum error correction process, and a reinforcement learning agent refined the process to account for defects in the experimental setup and the controller.