Investigation of IBMQ quantum device hardware calibration with Markovian master equation.

Abstract

In the design of quantum technology, it is crucial to account for the quantum system interacting with its environment to understand the influence of thermal processes and design the devices to avoid e↵ects of relaxation and decoherence of quantum states deteriorating the system beyond use. To accomplish this, a broadening of ideal isolated quantum mechanics is required, namely the theory of open quantum systems. This is most prevalent in the research of quantum error correction, which ensures that the initial quantum state remains intact when it is received and doesn’t decay into a di↵erent state which would change the information carried by the qubit. To investigate the intersection of all these phenomena, open-access cloud-computing services o↵er the ideal experimental environment. One such test-bed is o↵ered by IBM in their Quantum Experience platform which allows for remote access to quantum devices. The IBMQ quantum processors, which make use of superconducting qubit technology, are openly accessible through a cloud service. As such, they have been the focus of a lot of research into the evolution of quantum states while interacting with the environment. In the study of open quantum systems, an assumption is often made that the system and environment share no memory of the interaction of individual quantum states, which simplifies the analysis of the system’s evolution while also being e↵ectively true for large enough systems. Systems that obey this assumption are known as Markovian. New research has devised methods of error correction and tomography of quantum processors when this assumption no longer holds. Additionally, the calibration of the IBMQ processors performed by IBM to provide hardware parameters is performed through a set of techniques that are not guaranteed to yield cohesive results. These primary factors, among others, give rise to the research discussed in this dissertation, and pose the question of how accurate the hardware calibrations are when compared to results obtained through experiments performed on the devices. Furthermore, the approach uses the theory of open quantum systems to assess the hardware calibration while also testing whether the Markovian assumption of a memoryless system holds for the IBMQ quantum devices. This gives insight into the current state of superconducting quantum computers while providing a possible new avenue for quantum error correction from the perspective of the theory of open quantum systems.