Optimal Control of Spin Qudits Subject to Decoherence Using Amplitude-and-Frequency-Constrained Pulses
arXiv:2403.15785 · doi:10.1088/2058-9565/adbf44
Abstract
Quantum optimal control theory (QOCT) can be used to design the shape of electromagnetic pulses that implement operations on quantum devices. By using non-trivially shaped waveforms, gates can be made significantly faster than those built by concatenating monochromatic pulses. Recently, we applied this technique to the control of molecular spin qudits modelled with Schrödinger's equation and showed it can speed up operations, helping mitigate the effects of decoherence [Phys. Rev. Appl. 17, 064028 (2022)]. However, short gate times result in large optimal pulse amplitudes, which may not be experimentally accessible. Introducing bounds to the amplitudes then unavoidably leads to longer operation times, for which decoherence can no longer be neglected. Here, we study how to improve this procedure by applying QOCT on top of Lindblad's equation, to design control pulses accounting for decoherence already in the optimization process. In addition, we introduce a formulation that allows us to bound the maximum amplitude and frequency of the signals, which are the typical limitations of waveform generators. The pulses we obtain consistently enhance operation fidelities compared to those achieved with Schrödinger's equation across various target gates and durations, demonstrating the flexibility and robustness of our method. The improvement is larger the shorter the spin coherence time .
arXiv comment10 pages, 4 figures
References in corpus (35)
- Quantum Computing in Molecular Magnets
- Encoding a qubit in an oscillator
- Suppressing quantum errors by scaling a surface code logical qubit
- Control of quantum phenomena: Past, present, and future
- Training Schrödinger's cat: quantum optimal control
- A universal qudit quantum processor with trapped ions
- Operating Quantum States in Single Magnetic Molecules: Implementation of Grover's Quantum Algorithm
- Molecular Quantum Computing by an Optimal Control Algorithm for Unitary Transformations
- Optimal control theory for unitary transformations
- Demonstration of fault-tolerant universal quantum gate operations
- Experimental non-classicality of an indivisible quantum system
- Controlling open quantum systems: Tools, achievements, and limitations
- Fault-tolerant operation of a logical qubit in a diamond quantum processor
- Quantum error correction with silicon spin qubits
- Gradient optimization of analytic controls: the route to high accuracy quantum optimal control
- Coherent electrical control of a single high-spin nucleus in silicon
- Three addressable spin qubits in a molecular single-ion magnet
- Optimal Control for Generating Quantum Gates in Open Dissipative Systems
- Single qudit realization of the Deutsch algorithm using superconducting many-level quantum circuits
- Robust control of quantum gates via sequential convex programming
- A perspective on scaling up quantum computation with molecular spins
- Controlling the Dynamics of Many-Electron Systems from First Principles: A Marriage of Optimal Control and Time-Dependent Density-Functional Theory
- Optimal control theory for a unitary operation under dissipative evolution
- Criteria for Exact Qudit Universality
- Monotonically convergent optimal control theory of quantum systems with spectral constraints on the control field
- Quantum Optimal Control in a Chopped Basis: Applications in Control of Bose-Einstein Condensates
- Quantum optimal control via gradient ascent in function space and the time-bandwidth quantum speed limit
- Minimal qudit code for a qubit in the phase-damping channel
- Proof-of-concept Quantum Simulator based on Molecular Spin Qudits
- Navigating the 16-dimensional Hilbert space of a high-spin donor qudit with electric and magnetic fields
- Blueprint of a Molecular Spin Quantum Processor
- Counteracting dephasing in Molecular Nanomagnets by optimized qudit encodings
- Optimal control under spectral constraints: Enforcing multi-photon absorption pathways
- Quantifying quantum coherence of multiple-charge states in tunable Josephson junctions
- Calibration of Drive Non-Linearity for Arbitrary-Angle Single-Qubit Gates Using Error Amplification