Dynamical decoupling sequences for multi-qubit dephasing suppression and long-time quantum memory

Dynamical decoupling sequences for multi-qubit dephasing suppression and long-time quantum memory

Blog Article

We consider a class of multi-qubit dephasing models that combine classical noise sources and linear coupling to a bosonic environment, and are Circuit Boards controlled by arbitrary sequences of dynamical decoupling pulses.Building on a general transfer filter-function framework for open-loop control, we provide an exact representation of the controlled dynamics for arbitrary stationary non-Gaussian classical and quantum noise statistics, with analytical expressions emerging when all dephasing sources are Gaussian.This exact characterization is used to establish two main results.First, we construct multi-qubit sequences that ensure maximum high-order error suppression in both the time and frequency domain and that can be exponentially more efficient than existing ones in terms of total pulse number.Next, we show how long-time multi-qubit storage may be achieved by meeting appropriate conditions for the emergence of a fidelity plateau under sequence repetition, thereby generalizing recent results for single-qubit memory under Gaussian dephasing.

In both scenarios, the key step is Adjustment pull Pin to endow multi-qubit sequences with a suitable displacement anti-symmetry property, which is of independent interest for applications ranging from environment-assisted entanglement generation to multi-qubit noise spectroscopy protocols.