Quantum speed limits and control of multi-qubit quantum technologies
Abstract
The proposed research aims to drastically reduce the impact of decoherence, control errors, and other challenges facing quantum information technologies by building on recent breakthroughs in quantum control achieved by the PI under prior ONR support. These include the discovery of a geometric structure hidden within the Schrodinger equation that enables the design of errorcorrecting control pulses beyond what is possible using only numerical techniques. This approach, called Space Curve Quantum Control (SCQC), was used by the PI to design control pulses that dynamically suppress several of the most common types of noise afflicting leading hardware such as qubits based on superconducting circuits or spins in semiconductors. The proposed project will vastly broaden the scope of this framework by employing it to understand how to control multiqubit processors to perform quantum computational tasks in the shortest possible time. SCQC will also be leveraged to establish a new methodology for dynamically engineering a wide range of target many-body Hamiltonians using smooth, experimentally feasible waveforms. These advances will be employed to boost the control performance of state-of-the-art semiconducting, superconducting, and atomic qubit hardware.Performing quantum operations as quickly as possible is important for all quantum information technologies due to coherence time limitations and the desire to reduce the overall runtimeof applications. It has been known since the 1940s that quantum mechanics imposes fundamental limits on the time it takes to evolvequantum states. The proposed research will combine SCQC with foundational results in the mathematics of space curves to design control schemes that evolve multi-level or multi-qubit quantum systems at the quantum speed limit to mitigate decoherence, boost operation fidelities, and reduce application runtimes as much as possible. Hamiltonian engineering is a widely used technique in which one applies carefully designed control protocols to a given quantum system such that the time-averaged Hamiltonian governing the resulting evolution approximates a desired target Hamiltonian. Depending on the control fields one applies, this target Hamiltonian can be very different from the initial, static Hamiltonian. This technique is employed in quantum simulation to access a much larger set ofmany-bodyHamiltonians beyond what is realizable in the static case. It is also the mechanism that underlies dynamical decoupling. The proposed research will leverage SCQC to develop a new paradigm of Hamiltonian engineering that uses continuous rather than discretized control pulses to vastly expand the range of effective Hamiltonians that can be realized in a multi-qubit quantum system. The proposed research will apply SCQC to devise improved control schemes for leading qubit platforms, including superconducting, semiconducting, and atomic qubits. Although the quality of gate operations in quantum devices has steadily improved over the past two decades, significant room for further improvement remains. Enhancing gate fidelities further is crucial both for getting the most out of near-term quantum hardware, and for reducing the resource overhead needed to run quantum error correction on future hardware.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 13, 2025
- Source ID
- N000142512125
Entities
People
- Edwin Barnes
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech