1000 Times faster: Swedish breakthrough cuts quantum computer error risks

Researchers at Chalmers University of Technology, in collaboration with Tianjin University, have developed a single-period Floquet control method using “quantum lattice gates” to execute operations on bosonic quantum codes over a thousand times faster than previous approaches

Published in Physical Review Letters, the theoretical breakthrough addresses a major latency bottleneck in quantum error correction for superconducting circuits.

The challenge: Decoherence and multi-cycle latency

Quantum computing platforms based on individual two-level qubits are highly sensitive to environmental noise, such as thermal fluctuations, electrical interference, and cosmic radiation. Long gate execution times increase the window of exposure to environmental decoherence, accumulating errors before error-correction algorithms can resolve them.

To increase resilience, researchers use bosonic quantum codes, which store quantum information across continuous-variable microwave fields in superconducting resonators rather than single physical qubits.

However, controlling and shaping these bosonic states previously required driving the quantum system through thousands of repeated control cycles, creating a time-consuming bottleneck that exposed the fragile states to environmental noise.

The breakthrough: Single-period floquet control via quantum lattice gates

Lead author Lei Du, along with co-authors Tangyou Huang and Lingzhen Guo, resolved this operational bottleneck by introducing single-period Floquet engineering:

• Single-cycle execution:

  • The new method implements quantum lattice gates, a universal elementary gate set for controlling bosonic codes, within a single periodic driving cycle, reducing multi-thousand-cycle operations to a single pulse period.

• Over 1000x speedup:

  • By collapsing thousands of Floquet control cycles into one, the execution speed of complex bosonic quantum operations increases by more than three orders of magnitude.

• Reduced error accumulation:

  • Completing operations significantly faster reduces the time window during which external disturbances can corrupt quantum memory, bringing practical quantum error correction closer to realisation.

Experimental feasibility and integration

The single-period Floquet method is specifically tailored for superconducting quantum hardware platforms, such as the 100-qubit quantum computer currently under development at Chalmers within the Wallenberg Centre for Quantum Technology (WACQT).

Because the control protocol requires no radical hardware alterations, the authors are collaborating with experimentalists to demonstrate the technique using existing superconducting circuit architectures.