Ashley Donovan

Exploring the tradeoff between fidelity and time optimal control of quantum unitary transformations

Generating a unitary transformation in the shortest possible time is of practical importance to quantum information processing because it helps to reduce decoherence effects and improve robustness to additive control field noise. Many analytical and numerical studies have identified the minimum time necessary to implement a variety of quantum gates on coupled-spin qubit systems. This work focuses on exploring the Pareto front that quantifies the trade-off between the competitive objectives of maximizing the gate fidelity

Characterization of control noise effects in optimal quantum unitary dynamics

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Back and forth nudging for quantum state reconstruction

and minimizing the control time

Exploring quantum control landscape structure

T

Local topology at limited resource induced suboptimal traps on the quantum control landscape

. In order to identify the critical time

Exploring the complexity of quantum control optimization trajectories

T^{\ast}

Systematically altering the apparent topology of constrained quantum control landscapes

, below which the target transformation is not reachable, as well as to determine the associated Pareto front, we introduce a numerical method of Pareto front tracking (PFT). We consider closed two- and multi-qubit systems with constant inter-qubit coupling strengths and each individual qubit controlled by a separate time-dependent external field. Our analysis demonstrates that unit fidelity (to a desired numerical accuracy) can be achieved at any

Quantum control by means of Hamiltonian structure manipulation

T \geq T^{\ast}

Pathway dynamics in the optimal quantum control of rubidium: Cooperation and competition

in most cases. However, the optimization search effort rises superexponentially as

Exploring the impact of constraints in quantum optimal control through a kinematic formulation

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