Saving and loading from files

The package provides methods to load and save many classes to the disk. In particular, the following classes are serializable:

• Polynomial
• ChebyshevTExpansion
• XQSPPhaseFactors
• YQSPPhaseFactors
• GQSPPhaseFactors
• ChebyshevQSPPhaseFactors
• QSVTPhaseFactors

Each of these classes provides two methods dump_json() and load_json(), both of which take a path to a file or a file stream.

from nlft_qsp import *

P = Polynomial([1/7, 0, 1/5, 0, 1/6])

P.dump_json('P.qspx')

from nlft_qsp import *

P = Polynomial.load_json('P.qspx')

pf = QSVTPhaseFactors.solve(P)

pf.dump_json('protocol.qspx')

Command line interface

qspx takes files as arguments for its inputs and outputs. The following command computes the phase factors of an analytic generalized QSP protocol (ag) for the polynomial given in the file P.qspx and saves the computed protocol into the file protocol.qspx.

qspx solve -tag P.qspx -o protocol.qspx

Both inputs and outputs can be specified as -, which is the standard POSIX for standard input/standard output, respectively (for the output, this is the default). This is useful for usual piping in bash:

qspx make protocol.qspx | qspx plot - -f '0.5*np.cos(3*x)'

The above example takes the QSVT protocol saved in protocol.qspx, and plots the implemented polynomial in \([-1, 1]\) along with another function \(f(x) = \frac{1}{2} \cos(3x)\) for comparison.