A three-fold increase in quantum fidelity decay rates was achieved on IBM Quantum devices through a new dynamical decoupling approach, demonstrating performance gains on existing hardware. Researchers led by Ethan Hickman of the Joint Center for Quantum Information and Computer Science at the University of Maryland and Gregory Quiroz of the Johns Hopkins Applied Physics Laboratory utilized modified pulse timing to create a crosstalk-robust protocol, successfully tested on systems with up to 20 qubits. The team’s findings challenge the assumption that tunable-coupler devices inherently mitigate error, as fixed-coupler devices, when protected by dynamical decoupling, outperformed their tunable counterparts in experiments. The researchers write that their method broadens the scope of practical dynamical decoupling protocols, offering modest overhead and a reasonable constraint on qubit topology to attain significant performance improvements on modern quantum computing devices.
Pulse Timing Modifications Enhance Dynamical Decoupling Fidelity
A threefold increase in the rate at which quantum information degrades was achieved through subtle adjustments to the timing of control pulses, a result demonstrating immediate gains on currently available quantum hardware. The team’s approach, detailed in a recent publication in Physical Review Applied, focuses on modifying pulse timings within standard dynamical decoupling sequences, enhancing their resilience to noise without requiring substantial changes to existing quantum architectures. The experiments leveraged IBM Quantum Platform devices, including systems with up to 20 qubits utilizing fixed-coupler designs; this scale demonstrates the protocol’s potential for implementation in larger, more complex quantum processors.
The study revealed an unexpected outcome regarding qubit connectivity; fixed-coupler devices, when shielded by this optimized dynamical decoupling, outperformed those employing tunable couplers. The researchers explained that Z Z-robust sequences perform nearly equivalently to nonrobust dynamical decoupling, affirming the reduced impact of such errors in a tunable-coupler architecture, suggesting that dynamical decoupling can be more impactful than relying solely on hardware features to mitigate errors. This advancement is not merely theoretical; the team reports a measurable improvement in fidelity decay rates, indicating a tangible benefit for practical quantum computations.
ZZ Error Impact on Fixed and Tunable-Coupler Devices
Demonstrations on IBM Quantum devices reveal a dynamic in error mitigation strategies; while tunable couplers are often used for their ability to dynamically adjust qubit connectivity and reduce crosstalk, recent experiments suggest dynamical decoupling offers a more substantial benefit to fixed-coupler architectures. This challenges the prevailing assumption that tunable couplers inherently lessen the impact of errors, indicating that the effectiveness of dynamical decoupling may be more pronounced when applied to systems with static connections. The team’s approach, which modifies pulse timing within dynamical decoupling sequences, was tested on systems utilizing up to 20 qubits on IBM’s fixed-coupler hardware, and a key metric of success was a measured three-fold improvement in fidelity decay rate compared to standard, non-robust dynamical decoupling variants.
