Error-correcting multi-qubit quantum control for quantum-based technologies
Abstract
tasks far beyond present-day means is the central goal in the fields of quantum computing, sensing,and communication. These goals demand the ability to control and entangle microscopic quantumsystems with unprecedented accuracy, a task that is particularly challenging due to unwantedinteractions with the surrounding environment. Such interactions cannot be removed completelythrough careful system engineering since some contact with the environment is necessary in orderto manipulate the quantum system. Therefore, achieving the requisite level of control requires thedevelopment of control protocols capable of coherently manipulating the systems whilesimultaneously mitigating the deleterious effects of the environment dynamically.The proposed research aims to drastically reduce the impact of decoherence and other adverseeffects hindering quantum information technologies by enabling the design of optimal controlschemes that implement multi-qubit operations while suppressing these effects. This will beachieved by building on recent breakthroughs in quantum control achieved by the PI under priorONR support. These include the discovery of a geometric structure hidden within the Schrdingerequation of a single qubit that enables one to obtain the entire set of error-correcting control pulses.In recent preliminary work, the PI showed that a similar structure exists for multi-qubit systems.The proposed research will exploit this finding to develop a more general geometric frameworkthat can be used to achieve high-fidelity control and entanglement generation in multi-level andmulti-qubit quantum systems. This framework will be leveraged not only to develop errorsuppressing control schemes, but also to classify multi-qubit entangling operations, which will inturn facilitate the design of optimal entangling gate operations for a given qubit platform andcontrol mechanism. In addition, the geometric approach will be combined with numerical optimalcontrol methods to accelerate pulse design and experimental testing. The techniques that will bedeveloped will apply to a broad range of physical systems, including trapped ions, superconductingcircuits, atomic defect centers, and other solid-state spin qubits, and will be compatible withexisting experimental methods for controlling these systems.The geometric framework proposed here offers several advantages over existing approaches toquantum control, which include analytical methods based on idealized pulse waveforms such assquare and delta-function pulses, as well as numerical techniques. Designs based on idealizedwaveforms are easy to obtain because of the tractability of the Schrdinger equation in this case;however, these have the drawback that they are unphysical and cannot be implemented in thelaboratory with high precision. More experimentally feasible pulse shapes can be obtained fromnumerical methods, but the challenge here is that globally optimal solutions are difficult to findbecause these approaches can only identify locally optimal points in a control field parameterspace. The geometric framework discovered by the PI overcomes both deficiencies at once byproviding a global view of the solution space of control fields, enabling one to identify optimal,experimentally feasible controls for a given task. This unique feature has the potential tosignificantly impact the field of quantum control and, consequently, quantum informationtechnologies. Unlocking this potential requires the development of a multi-qubit geometricframework, which is the objective of this proposal.Approved for public release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 05, 2021
- Source ID
- N000142112629
Entities
People
- Edwin Barnes
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech