Understanding GRAPE Code

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GRAPEResult class (represents result of grape simulation):

• u: GRAPE control pulse matrix
• H_t: time dependent Hamiltonian
• U_f: final unitary transformation

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Functions:

plot_grape_control_fields: Plots the GRAPE control fields given a control pulse matrix ; shows how control pulses change over time

_overlap: calculates overlap (similarity) between two quantum objects (like states or operations)

grape_unitary: determines what is control pulses are necessary to make a quantum system evolve a certain way

cy_grape_unitary: similar to grape_unitary but more efficient; uses Cython

grape_unitary_adaptive: similar to grape_unitary but with adaptive features ; can change step size (eps)

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Necessary packages:

numpy: for math functions, numerical computations, array operations

scipy: uses interpld function from scipy.interpolate for interpolation (which is estimating values that lie between known data points)

qutip:

• Qobj : to represent quantum objects (quantum states/operators) in QuTiP
• qeye: which represents the identity operator
• qutip.core and _data: helps with handling quantum data
• qutip.ui and BaseProgressBar: qutip provides module for displaying progress bars during long simulations
• qutip_qtrl and cy_overlap: computes overlap between two quantum states or operators
• qutip_qtrl and cy_grape_inner: tweaks control pulses; helps to optimize these pulses