def _generate_fit_guesses(
self,
user_opt: curve.FitOptions,
curve_data: curve.CurveData,
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Create algorithmic guess with analysis options and curve data.
Args:
user_opt: Fit options filled with user provided guess and bounds.
curve_data: Formatted data collection to fit.
Returns:
List of fit options that are passed to the fitter function.
"""
max_abs_y, _ = curve.guess.max_height(curve_data.y, absolute=True)
user_opt.bounds.set_if_empty(
amp=(-2 * max_abs_y, 2 * max_abs_y),
tau=(0, np.inf),
base=(-max_abs_y, max_abs_y),
phase=(-np.pi, np.pi),
)
# Default guess values
freq_guesses, base_guesses = [], []
for series in ["X", "Y"]:
data = curve_data.get_subset_of(series)
freq_guesses.append(curve.guess.frequency(data.x, data.y))
base_guesses.append(curve.guess.constant_sinusoidal_offset(data.y))
freq_val = float(np.average(freq_guesses))
user_opt.p0.set_if_empty(base=np.average(base_guesses))
# Guess the exponential decay by combining both curves
data_x = curve_data.get_subset_of("X")
data_y = curve_data.get_subset_of("Y")
decay_data = (data_x.y - user_opt.p0["base"]) ** 2 + (data_y.y - user_opt.p0["base"]) ** 2
user_opt.p0.set_if_empty(
tau=-curve.guess.exp_decay(data_x.x, decay_data),
amp=0.5,
phase=0.0,
)
opt_fp = user_opt.copy()
opt_fp.p0.set_if_empty(freq=freq_val)
opt_fm = user_opt.copy()
opt_fm.p0.set_if_empty(freq=-freq_val)
return [opt_fp, opt_fm]
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
"""
curve_data = self._data()
max_abs_y, _ = curve.guess.max_height(curve_data.y, absolute=True)
user_opt.bounds.set_if_empty(
amp=(-2 * max_abs_y, 2 * max_abs_y),
freq=(0, np.inf),
phase=(-np.pi, np.pi),
base=(-max_abs_y, max_abs_y),
)
user_opt.p0.set_if_empty(
freq=curve.guess.frequency(curve_data.x, curve_data.y),
base=curve.guess.constant_sinusoidal_offset(curve_data.y),
)
user_opt.p0.set_if_empty(
amp=curve.guess.max_height(curve_data.y - user_opt.p0["base"], absolute=True)[0],
)
options = []
for phase_guess in np.linspace(0, np.pi, 5):
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(phase=phase_guess)
options.append(new_opt)
return options
def _generate_fit_guesses(
self,
user_opt: curve.FitOptions,
curve_data: curve.CurveData,
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Create algorithmic guess with analysis options and curve data.
Args:
user_opt: Fit options filled with user provided guess and bounds.
curve_data: Formatted data collection to fit.
Returns:
List of fit options that are passed to the fitter function.
"""
# Use a fast Fourier transform to guess the frequency.
x_data = curve_data.get_subset_of("series-0").x
min_beta, max_beta = min(x_data), max(x_data)
# Use the highest-frequency curve to estimate the oscillation frequency.
series_label, reps_label = max(
("series-0", "reps0"),
("series-1", "reps1"),
("series-2", "reps2"),
key=lambda x: self.options.fixed_parameters[x[1]],
)
curve_data = curve_data.get_subset_of(series_label)
reps2 = self.options.fixed_parameters[reps_label]
freqs_guess = curve.guess.frequency(curve_data.x, curve_data.y) / reps2
user_opt.p0.set_if_empty(freq=freqs_guess)
avg_x = (max(x_data) + min(x_data)) / 2
span_x = max(x_data) - min(x_data)
beta_bound = max(5 / user_opt.p0["freq"], span_x)
ptp_y = np.ptp(curve_data.y)
user_opt.bounds.set_if_empty(
amp=(-2 * ptp_y, 0),
freq=(0, np.inf),
beta=(avg_x - beta_bound, avg_x + beta_bound),
base=(min(curve_data.y) - ptp_y, max(curve_data.y) + ptp_y),
)
base_guess = (max(curve_data.y) - min(curve_data.y)) / 2
user_opt.p0.set_if_empty(base=(user_opt.p0["amp"] or base_guess))
# Drag curves can sometimes be very flat, i.e. averages of y-data
# and min-max do not always make good initial guesses. We therefore add
# 0.5 to the initial guesses. Note that we also set amp=-0.5 because the cosine function
# becomes +1 at zero phase, i.e. optimal beta, in which y data should become zero
# in discriminated measurement level.
options = []
for amp_factor in (-1, -0.5, -0.25):
for beta_guess in np.linspace(min_beta, max_beta, 20):
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(amp=ptp_y * amp_factor,
beta=beta_guess)
options.append(new_opt)
return options
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
"""
user_opt.bounds.set_if_empty(
a=(0, 1),
alpha=(0, 1),
alpha_c=(0, 1),
b=(0, 1),
)
# for standard RB curve
std_curve = self._data(series_name="Standard")
opt_std = user_opt.copy()
opt_std = self._initial_guess(opt_std, std_curve.x, std_curve.y,
self._num_qubits)
# for interleaved RB curve
int_curve = self._data(series_name="Interleaved")
opt_int = user_opt.copy()
if opt_int.p0["alpha_c"] is not None:
opt_int.p0["alpha"] = opt_std.p0["alpha"] * opt_int.p0["alpha_c"]
opt_int = self._initial_guess(opt_int, int_curve.x, int_curve.y,
self._num_qubits)
user_opt.p0.set_if_empty(
a=np.mean([opt_std.p0["a"], opt_int.p0["a"]]),
alpha=opt_std.p0["alpha"],
alpha_c=min(opt_int.p0["alpha"] / opt_std.p0["alpha"], 1),
b=np.mean([opt_std.p0["b"], opt_int.p0["b"]]),
)
return user_opt
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
"""
# Use a fast Fourier transform to guess the frequency.
x_data = self._data("series-0").x
min_beta, max_beta = min(x_data), max(x_data)
freqs_guesses = {}
for i in range(3):
curve_data = self._data(f"series-{i}")
freqs_guesses[f"freq{i}"] = curve.guess.frequency(
curve_data.x, curve_data.y)
user_opt.p0.set_if_empty(**freqs_guesses)
max_abs_y, _ = curve.guess.max_height(self._data().y, absolute=True)
freq_bound = max(10 / user_opt.p0["freq0"], max(x_data))
user_opt.bounds.set_if_empty(
amp=(-2 * max_abs_y, 0),
freq0=(0, np.inf),
freq1=(0, np.inf),
freq2=(0, np.inf),
beta=(-freq_bound, freq_bound),
base=(-max_abs_y, max_abs_y),
)
user_opt.p0.set_if_empty(base=0.5)
# Drag curves can sometimes be very flat, i.e. averages of y-data
# and min-max do not always make good initial guesses. We therefore add
# 0.5 to the initial guesses. Note that we also set amp=-0.5 because the cosine function
# becomes +1 at zero phase, i.e. optimal beta, in which y data should become zero
# in discriminated measurement level.
options = []
for amp_guess in (0.5, -0.5):
for beta_guess in np.linspace(min_beta, max_beta, 20):
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(amp=amp_guess, beta=beta_guess)
options.append(new_opt)
return options
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
Raises:
CalibrationError: When ``angle_per_gate`` is missing.
"""
n_guesses = self._get_option("number_guesses")
curve_data = self._data()
max_abs_y, _ = curve.guess.max_height(curve_data.y, absolute=True)
max_y, min_y = np.max(curve_data.y), np.min(curve_data.y)
user_opt.bounds.set_if_empty(d_theta=(-np.pi, np.pi),
base=(-max_abs_y, max_abs_y))
user_opt.p0.set_if_empty(base=(max_y + min_y) / 2)
if "amp" in user_opt.p0:
user_opt.p0.set_if_empty(amp=max_y - min_y)
user_opt.bounds.set_if_empty(amp=(-2 * max_abs_y, 2 * max_abs_y))
# Base the initial guess on the intended angle_per_gate.
angle_per_gate = self._get_option("angle_per_gate")
if angle_per_gate is None:
raise CalibrationError(
"The angle_per_gate was not specified in the analysis options."
)
guess_range = max(abs(angle_per_gate), np.pi / 2)
options = []
for d_theta_guess in np.linspace(-guess_range, guess_range, n_guesses):
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(d_theta=d_theta_guess)
options.append(new_opt)
return options
def _generate_fit_guesses(
self,
user_opt: curve.FitOptions,
curve_data: curve.CurveData,
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Create algorithmic guess with analysis options and curve data.
Args:
user_opt: Fit options filled with user provided guess and bounds.
curve_data: Formatted data collection to fit.
Returns:
List of fit options that are passed to the fitter function.
"""
fixed_params = self.options.fixed_parameters
max_abs_y, _ = curve.guess.max_height(curve_data.y, absolute=True)
max_y, min_y = np.max(curve_data.y), np.min(curve_data.y)
user_opt.bounds.set_if_empty(d_theta=(-0.8 * np.pi, 0.8 * np.pi),
base=(-max_abs_y, max_abs_y))
user_opt.p0.set_if_empty(base=(max_y + min_y) / 2)
if "amp" in user_opt.p0:
user_opt.p0.set_if_empty(amp=max_y - min_y)
user_opt.bounds.set_if_empty(amp=(0, 2 * max_abs_y))
amp = user_opt.p0["amp"]
else:
# Fixed parameter
amp = fixed_params.get("amp", 1.0)
# Base the initial guess on the intended angle_per_gate and phase offset.
apg = user_opt.p0.get("angle_per_gate",
fixed_params.get("angle_per_gate", 0.0))
phi = user_opt.p0.get("phase_offset",
fixed_params.get("phase_offset", 0.0))
# Prepare logical guess for specific condition (often satisfied)
d_theta_guesses = []
offsets = apg * curve_data.x + phi
for i in range(curve_data.x.size):
xi = curve_data.x[i]
yi = curve_data.y[i]
if np.isclose(offsets[i] % np.pi, np.pi / 2) and xi > 0:
# Condition satisfied: i.e. cos(apg x - phi) = 0
err = -np.sign(np.sin(offsets[i])) * (
yi - user_opt.p0["base"]) / (0.5 * amp)
# Validate estimate. This is just the first order term of Maclaurin expansion.
if np.abs(err) < 0.5:
d_theta_guesses.append(err / xi)
else:
# Terminate guess generation because larger d_theta x will start to
# reduce net y value and underestimate the rotation.
break
# Add naive guess for more coverage
guess_range = max(abs(apg), np.pi / 2)
d_theta_guesses.extend(np.linspace(-guess_range, guess_range, 11))
options = []
for d_theta_guess in d_theta_guesses:
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(d_theta=d_theta_guess)
options.append(new_opt)
return options
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
"""
curve_data = self._data()
user_opt.p0.set_if_empty(
amp=0.5,
base=curve.guess.constant_sinusoidal_offset(curve_data.y),
)
# frequency resolution of this scan
df = 1 / ((curve_data.x[1] - curve_data.x[0]) * len(curve_data.x))
if user_opt.p0["freq"] is not None:
# If freq guess is provided
freq_guess = user_opt.p0["freq"]
freqs = [freq_guess]
else:
freq_guess = curve.guess.frequency(curve_data.x, curve_data.y - user_opt.p0["base"])
# The FFT might be up to 1/2 bin off
if freq_guess > df:
freqs = [freq_guess - df, freq_guess, freq_guess + df]
else:
freqs = [0.0, freq_guess]
# Set guess for decay parameter based on estimated frequency
if freq_guess > df:
alpha = curve.guess.oscillation_exp_decay(
curve_data.x, curve_data.y - user_opt.p0["base"], freq_guess=freq_guess
)
else:
# Very low frequency. Assume standard exponential decay
alpha = curve.guess.exp_decay(curve_data.x, curve_data.y)
if alpha != 0.0:
user_opt.p0.set_if_empty(tau=-1 / alpha)
else:
# Likely there is no slope. Cannot fit constant line with this model.
# Set some large enough number against to the scan range.
user_opt.p0.set_if_empty(tau=100 * np.max(curve_data.x))
user_opt.bounds.set_if_empty(
amp=[0, 1.5],
base=[0, 1.5],
tau=(0, np.inf),
freq=(0, 10 * freq_guess),
phi=(-np.pi, np.pi),
)
# more robust estimation
options = []
for freq in freqs:
for phi in np.linspace(-np.pi, np.pi, 5)[:-1]:
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(freq=freq, phi=phi)
options.append(new_opt)
return options
def _generate_fit_guesses(
self, user_opt: curve.FitOptions
) -> Union[curve.FitOptions, List[curve.FitOptions]]:
"""Compute the initial guesses.
Args:
user_opt: Fit options filled with user provided guess and bounds.
Returns:
List of fit options that are passed to the fitter function.
"""
user_opt.bounds.set_if_empty(t_off=(0, np.inf), b=(-1, 1))
user_opt.p0.set_if_empty(t_off=self._t_off_initial_guess(), b=1e-9)
guesses = defaultdict(list)
for control in (0, 1):
x_data = self._data(series_name=f"x|c={control}")
y_data = self._data(series_name=f"y|c={control}")
z_data = self._data(series_name=f"z|c={control}")
omega_xyz = []
for data in (x_data, y_data, z_data):
ymin, ymax = np.percentile(data.y, [10, 90])
if ymax - ymin < 0.2:
# oscillation amplitude might be almost zero,
# then exclude from average because of lower SNR
continue
fft_freq = curve.guess.frequency(data.x, data.y)
omega_xyz.append(fft_freq)
if omega_xyz:
omega = 2 * np.pi * np.average(omega_xyz)
else:
omega = 1e-3
zmin, zmax = np.percentile(z_data.y, [10, 90])
theta = np.arccos(np.sqrt((zmax - zmin) / 2))
# The FFT might be up to 1/2 bin off
df = 2 * np.pi / ((z_data.x[1] - z_data.x[0]) * len(z_data.x))
for omega_shifted in [omega, omega - df / 2, omega + df / 2]:
for phi in np.linspace(-np.pi, np.pi, 5):
px = omega_shifted * np.cos(theta) * np.cos(phi)
py = omega_shifted * np.cos(theta) * np.sin(phi)
pz = omega_shifted * np.sin(theta)
guesses[control].append(
{
f"px{control}": px,
f"py{control}": py,
f"pz{control}": pz,
}
)
if omega < df:
# empirical guess for low frequency case
guesses[control].append(
{
f"px{control}": omega,
f"py{control}": omega,
f"pz{control}": 0,
}
)
fit_options = []
# combine all guesses in Cartesian product
for p0s, p1s in product(guesses[0], guesses[1]):
new_opt = user_opt.copy()
new_opt.p0.set_if_empty(**p0s, **p1s)
fit_options.append(new_opt)
return fit_options
