Purdue's Quantum Breakthrough Stabilizes Qubits at 90.8% Fidelity
Researchers at Purdue University have made a breakthrough in quantum computing by developing a new way to stabilise quantum states. The team, led by Qihao Guo, used engineered dissipation to control superconducting qubits with far greater precision than before. Their method marks a shift from simply shielding qubits from noise to actively harnessing dissipation for stabilisation. The technique relies on programmable local reservoirs, which act as controlled energy sinks and sources. These reservoirs allow the system to stabilise entangled states without constant external intervention. Tests on a one-dimensional array of coupled transmon qubits demonstrated the method’s effectiveness, achieving a fidelity of 90.8% in stabilised single-excitation states.
Superconducting circuits were chosen for their ability to fine-tune interactions with dissipative environments. By engineering these interactions, the team realised a Bose-Hubbard model for microwave photons, enabling remote entanglement through waveguides. The approach also stabilised protected bosonic states, a key requirement for autonomous quantum error correction. While the current method excels with single-excitation states, multi-excitation states remain a significant hurdle. Despite this, the framework offers a scalable and hardware-efficient way to prepare and control complex quantum systems.
The new method has pushed entanglement fidelity to 90.8%, a major leap over previous results. It provides a practical path toward more reliable quantum control, particularly in superconducting architectures. Future work will need to address the challenge of extending stabilisation to multi-excitation states.
