Protectability of IBMQ Qubits by Dynamical Decoupling Technique

Abstract

We study the current effectiveness of the dynamical decoupling technique on a publicly accessible IBM quantum computer (IBMQ). This technique, also known as bang-bang decoupling or dynamical symmetrization, consists of applying sequences of pulses for protecting a qubit from decoherence by symmetrizing the qubit–environment interactions. Works in the field have studied sequences with different symmetries and carried out tests on IBMQ devices typically considering single-qubit states. We show that the simplest universal sequences can be interesting for preserving two-qubit states on the IBMQ device. For this, we considered a collection of single-qubit and two-qubit states. The results indicate that a simple dynamical decoupling approach using available IBMQ pulses is not enough for protecting a general single-qubit state without further care. Nevertheless, the technique is beneficial for the Bell states. This encouraged us to study logical qubit encodings such as |0⟩L≡|01⟩,|1⟩L≡|10⟩, where a quantum state has the form |ψab⟩=a|0⟩L+b|1⟩L. Thus, we explored the effectiveness of dynamical decoupling with a large set of two-qubit |ψab⟩ states, where a and b are real amplitudes. With this, we also determined that the |ψab⟩ states most benefiting from this dynamical decoupling approach and slowed down the decay of their survival probability.